Lumenzia – Not Just for Landscapes

Luminosity Masking is NOT just for landscape photographs – far from it.

But most folk miss the point of luminosity masking because they think it’s difficult and tedious.

The point, as I always see it, is that luminosity masking allows you to make dramatic but subtle changes and enhancements to your image with what are actually VERY fast and crude “adjustments”.

This in reality means that luminosity masking is FAST – and way faster than trying to do “localised” adjustments.  But the creation of the masks and choosing which one to use is what crippled the “ease factor” for most.

But with this new Lumenzia extension is so snappy and quick at showing you the different masks that, if you know what area of the image you want to adjust, the whole process takes SECONDS.

Let’s look at a White-tailed Eagle taken just 15 days ago:

Straight off the 1Dx it looks like this:

RAW unprocessed .CR2 file

RAW unprocessed .CR2 file (CLICK to view in new window)

Inside the Develop Module of Lightroom 5 it looks like:

camera

RAW unprocessed – (CLICK to view in new window)

A few tweaks later and it looks like:

Lr5adjust

Tweaks are what you can see in the Basics Panel + CamCal set to Neutral, and Chroma Noise removal in the Lens Corrections Panel is turned ON – (CLICK to view in new window)

Sending THIS adjusted image to Photoshop:

ps1

(CLICK to view in new window)

All I want to do is give a “lift” to the darker tones in the bird; under the wings, and around the side of head, legs and tail.

Using a BRUSH to do the job is all fine ‘n dandy BUT, you would be creating a localised adjustment that’s all-encompassing from a tonal perspective; all tones that fell under the brush get adjusted by the same amount.

A luminosity mask, or indeed ANY pixel-based mask is exactly what it says it is – a mask full of pixels. And those pixels are DERIVED from the real pixels in your image.  But the real beauty is that those pixels will be anywhere from 1% to 100% selected, or not selected at all.

Where they are 100% selected they are BLACK, and any adjustment you make BEHIND that mask will NOT be visible.

Pixels that are NOT selected will be WHITE, and your adjustment will show fully.

But where the pixels are between 1% and 99% selected they will appear as 1% GREY to 99% grey and so will show or hide variation of said adjustment by the same amounts…got it?

The Lumenzia D4 mask looks like it’ll do the job I want:

(CLICK to view in new window)

Lumenzia D4 mask (CLICK to view in new window)

Click the image to view larger – look at the subtle selections under those wings – try making that selection any other way in under 2 seconds – you’ve got no chance!

The “lift” I want to make in those WHITER areas of the mask is best done with a Curves Adjustment layer:

Select "Curve" in the Lumenzia GUI - (CLICK to view in new window)

Select “Curve” in the Lumenzia GUI – (CLICK to view in new window)

So hit the Curve button and voilà:

The Lumenzia D4 mask is now applied to Curves Adjustment Layer - (CLICK to view in new window)

The Lumenzia D4 mask is now applied to Curves Adjustment Layer – (CLICK to view in new window)

You can see in the image above that I’ve made a very rough upwards deflection of the curve to obtain an effective but subtle improvement to those under-wing areas etc. that I was looking to adjust.

The total time frame from opening the image in Photoshop to now is about 20 seconds!  Less time than the Lightroom 5 adjustments took…

And to illustrate the power of that Lumenzia D4 Luminosity mask, and the crudity of the adjustment I made, here’s the image WITHOUT THE MASK:

The effect of the luminosity mask is best illustrated by "hiding" it - bloody hell, turn it back on ! - (CLICK to view in new window).

The effect of the luminosity mask is best illustrated by “hiding” it – bloody hell, turn it back on ! – (CLICK to view in new window).

And at full resolution you can see the subtleties of the adjustment on the side of the head:

ll+lum

With Lumenzia (left) and just the Lightroom 5 processing (right) – (CLICK to view in new window).

If you want to get the best from your images AND you don’t want to spend hours trying to do so, then Lumenzia will seriously help you.

Clicking this link HERE to buy Lumenzia doesn’t mean it costs you any more than if you buy it direct from the developer.  But it does mean that I get a small remuneration from the developer as a commission which in turn supports my blog.  Buying Lumenzia is a total no-brainer so please help support this blog by buying it via these links – many thanks folks.

UPDATE June 2018: Greg Benz (the plugin author) has launched a comprehensive Lumenzia training course – see my post here for more information.

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View Autofocus Points in Lightroom

Mr. Malcolm Clayton sent me a link last week to a free plug-in for Lightroom that displays the autofocus points used for the shot, plus other very useful information such as focus distance, f-number and shutter speed, depth of field (DoF) values and other bits and bobs.

The plug-in is called “Show Focus Points” and you can download it HERE

Follow the installation instruction to the letter!

Once installed you can only launch it from the LIBRARY MODULE:

Accessing the Plug-in via the Library>Plug-in Extras menu

Accessing the Plug-in via the Library>Plug-in Extras menu CLICK to view LARGER

You will see this sort of thing:

The "Show Focus Points" for Lightroom plug-in window.

The “Show Focus Points” for Lightroom plug-in window. CLICK to view LARGER.

It’s a usefull tool to have because short of running the rather clunky Canon DPP or Nikon ViewNX software it’s the easiest way of getting hold of autofocus information without sending the image to Photoshop and looking through the mind-numbing RAW schema data – something I do out of habbit!

It displays a ton of useful data about your camera focus settings and exposure, and the autofocus point used – be it set by you, or chosen by the camera.

As far as I can see, the plug-in only displays the main active autofocus point on Nikon D4 and D4S files, but all the autofocus group as well as active points seem to display when viewing .CR2 Canon files as we can see on this very impressive car number plate!:

Screen grab of an unprocessed 1Dx/200-400/TC shot I did while testing the tracking capabilities of the Canon lens with the TC active - the REAL image looks more impressive than this!

Screen grab of an unprocessed 1Dx/200-400/TC shot I did while testing the tracking capabilities of the Canon lens with the TC active – the REAL image looks more impressive than this! I’m actually zooming out while tracking too – this is around 200mm + the 1.4x TC. CLICK to view LARGER

Canon 1Dx in AF Point Expansion 4 point; what I call "1 with 4 friends".

Canon 1Dx in AI Servo AF Point Expansion 4 point; what I call “1 with 4 friends”. CLICK to view LARGER.

Canon 1Dx in AI-F autofocus showing all autofocus points used be the camera.

Canon 1Dx in AI-F autofocus showing all autofocus points used be the camera.

Viewing your autofocus points is a very valid learning tool when trying to become familiar with your cameras autofocus, and it’s also handy if you want to see why and where you’ve “screwed the pooch” – hey, we ALL DO IT from time to time!

Useful tool to have IMO and it’s FREE – Andy likes free…

Cheers to Malc Clayton for bringing this to my attention.

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Autofocus Drill-down

Long Lens Autofocus Considerations.

If you read my previous post about the 1Dx sensor you will have seen that I mentioned my, as yet unfinished, tome about long lens autofocus for wildlife photography.  It’s a frustrating project because I keep having to change various bits to make them simpler, re-order certain paragraphs etc.

But I thought I’d blog-post something here that I expand on in the project, and it’s something an awful lot of people NEVER take into consideration.

As a Nikon user I’m used to the vagaries of the Nikon AF system and I manage to work with it just fine – I have to!

But photographers who don’t shoot wildlife, and don’t use 400mm or 500mm lumps of glass as their “standard lens” might not find the vagaries I bitch about quite so apparent; indeed some might not come across them at all.

As a wildlife photographer I shoot in crappy light, I shoot with slow lenses (both in terms of f-number and focus speed), I shoot low contrast subjects on equally low contrast backgrounds, I’m constantly shooting brown-on-brown, grey on grey etc, I shoot stupidly small subjects….the list goes on!

For years, good wildlife photography has been done by pushing camera/lens capabilities beyond their performance design parameters; and this particularly applies to our “expectations” of our latest and greatest AF system – be it Canon or Nikon.

I find so many people who come to my workshops etc. are not even aware of this one simple fact – sharp focus requires more work AND increased speed of work by the lens AF motor the closer a subject is to the camera.

Just try looking at the delineations on the focusing ring of a lens:

Canon 200-400 focused at 20 meters.

Canon 200-400 focused at 20 meters. (Lens porn WARNING: This lens will cause movements in the front-of-trouser department).

Look at the scale and note the distance between 20m and 50m marks – that distance is indicative of the amount of work required of the autofocus controller and motor to move from 20m to 50m or vice versa.

Now look where the 10m mark is – it requires FAR MORE work from the focus controller and motor to move from 20m to 10m, than it did to move the 30 meters from 50m to 20m.

On top of that extra work, if we are tracking a subject moving at 10 meters per second the lens takes 3 seconds to move from 50m to 20m, but then has to move a lot FASTER as well to cover the extra workload moving from 20m to 10m in just 1 second.

Then you wonder why your Nikon D40 + Sigma 50-500mm is crap at doing “birds in flight”; you never realise that your autofocus system is bag of spanners and powered by a hamster on a wheel…….it’s just not fast enough kids

Autofocus accuracy is nothing without speed if you are wanting to do productive wildlife photography.

As I alluded to before, as a photographer of the old wildlife I, and YOU will always encounter problems that users in other photographic disciplines may not, or if they do then the problem has a lot less impact than it does for us.

Think of it this way – a sports photographer will use a 500mm f4 to photograph a 6 foot tall overpaid git who’s 25m to 70m away, on a sunny Saturday afternoon or under a squillion watts of flood lighting; and he’s looking for a 6×12 for the back page of the Sunday Sport.  I’ll use the same lens to photograph a cute Red Squirrel at 5m to 7m in a gloomy wood in the middle of winter and I’m looking for a full size, full resolution image for stock.

Red Squirrel - this is basically the FURTHEST DISTANCE you could shoot at with a 500mm lens and still get a meaningful composition.

Red Squirrel – this is basically the FURTHEST DISTANCE you could shoot at with a 500mm lens and still get a meaningful composition. Click for larger view.

Note the distance – 631/100 – that means 6.31 meters. Aperture is f8, so DoF is around 7 centimeters.

The image is UNCROPPED as are all the other images in this post

We don’t really want to be any further away because “his cuteness” will be too small in the frame:

The factors effecting subject distance choice are:

  1.  lens resolving power – small, fine details need to be as close as possible.*
  2.  sensor resolving power – we need as many pixels as possible covering the subject.*
  3.  auto focus point placement accuracy – if the subject is too small in the frame, point placement is inaccurate.
  4. general “in camera” composition

*These two are inextricably intertwined

I’ve indicated the active focus point on the above image too  because here’s a depth of field “point of note” – autofocus wastes DoF.  Where is the plane of focus? Just between the eyes of the squirrel.

Assuming the accepted modern norm of DoF distribution – 50/50 – that’s 3.5 centimeters in front of the plane of focus, or indicted AF point, that will be sharp.  Only problem there is that the squirrel’s nose is only around 1 centimeter closer to the camera than the AF point, so the remaining 2 .5 centimeters of DoF is wasted on a sharp rendition of the fresh air between its nose and the camera!!

Now let’s change camera orientation and go a bit closer to get the very TIGHTEST shot composition:

Red Squirrel - this is basically the CLOSEST DISTANCE you could shoot at with a 500mm lens and still get a meaningful composition.

Red Squirrel – this is basically the CLOSEST DISTANCE you could shoot at with a 500mm lens and still get a meaningful composition. Click for larger view

The subject distance is 5.62 meters. Aperture is f6.3 so DoF is around 4.4 centimeters.

Now let’s change photographic hats and imagine we are a sports photographer and we are spending a Saturday afternoon photographing a bunch of over-paid 6 foot tall gits chasing a ball around a field, using the very same camera and lens:

He's not over-paid or chasing a ball, but this is the CLOSEST distance we can shoot at with this orientation and still get a "not too tight" composition of a 6 foot git! "Shep's" not a git really - well, not much!

He’s not over-paid or chasing a ball, but this is the CLOSEST distance we can shoot at with this orientation and still get a “not too tight” composition of a 6 foot git! “Shep’s” not a git really – well, not much! Click to enlarge

The distance for this shot is 29.9 meters. Aperture is f6.3 so DoF is around 1.34 meters.

And here we are at the CLOSEST distance for this horizontal camera orientation - still not too tight.

And here we are at the CLOSEST distance for this horizontal camera orientation – still not too tight. Click to enlarge.

The distance here is 50.1 meters. Aperture is f6.3 so DoF is around 3.79 meters.

So with this new “sports shooter” hat on, have we got an easier job than the cold, wet squirrel photographer?

You bet your sweet life we have!

The “Shepster” can basically jump around and move about like an idiot on acid and stay in sharp focus because:

  1. the depth of field at those distances is large.
  2. more importantly, the autofocus has VERY little work to do along the lens axis, because 1 or 2 meters of subject movement closer to the camera requires very small movements of the lens focus mechanicals.

But the poor wildlife photographer with his cute squirrel has so much more of a hard time getting good sharp shots because:

  1. he/she has got little or no depth of field
  2. small subject movements along the lens axis require very large and very fast movement of the lens focus mechanicals.

So the next time you watch a video by Canon or Nikon demonstrating the effectiveness of their new AF system on some new camera body or other; or you go trawling the internet looking for what AF settings the pros use, just bear in mind that “one mans fruit may be another mans poison” just because he/she photographs bigger subjects at longer average distances”.

Equipment choice and its manner of deployment and use is just not a level playing field is it…but it’s something a lot of folk don’t realise or think about.

And how many folk would ever consider that a desired “in camera” image composition has such a massive set of implications for autofocus performance – not many – but if you put your brain in gear it’s blindingly obvious.

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Colormunki Photo Update

Colormunki Photo Update

Both my MacPro and non-retina iMac used to be on Mountain Lion, or OSX 10.8, and nope, I never updated to Mavericks as I’d heard so many horror stories, and I basically couldn’t be bothered – hey, if it ain’t broke don’t fix it!

But, I wanted to install CapOne Pro on the iMac for the live-view capabilities – studio product shot lighting training being the biggest draw on that score.

So I downloaded the 60 day free trial, and whadyaknow, I can’t install it on anything lower than OSX 10.9!

Bummer thinks I – and I upgrade the iMac to OSX 10.10 – YOSEMITE.

Now I was quite impressed with the upgrade and I had no problems in the aftermath of the Yosemite installation; so after a week or so muggins here decided to do the very same upgrade to his late 2009 Mac Pro.

OHHHHHHH DEARY ME – what a pigs ear of a move that turned out to be!

Needless to say, I ended up making a Yosemite boot installer and setting up on a fresh HDD.  After re-installing all the necessary software like Lightroom and Photoshop, iShowU HD Pro and all the other crap I use, the final task arrived of sorting colour management out and profiling the monitors.

So off we trundle to X-Rite and download the Colormunki Photo software – v1.2.1.  I then proceeded to profile the 2 monitors I have attached to the Mac Pro.

Once the colour measurement stage got underway I started to think that it was all looking a little different and perhaps a bit more comprehensive than it did before.  Anyway, once the magic had been done and the profile saved I realised that I had no way of checking the new profile against the old one – t’was on the old hard drive!

So I go to the iMac and bring up the Colormunki software version number – 1.1.1 – so I tell the software to check for updates – “non available” came the reply.

Colormunki software downloads

Colormunki software downloads

Colormunki v1.2.1 for Yosemite

Colormunki v1.2.1 for Yosemite

So I download 1.2.1, remove the 1.1.1 software and restart the iMac as per X-Rites instructions, and then install said 1.2.1 software.

Once installation was finished I profiled the iMac and found something quite remarkable!

Check out the screen grab below:

iMac screen profile comparrisons.

iMac screen profile comparisons. You need to click this to open full size in a new tab.

On the left is a profile comparison done in the ColourThink 2-D grapher, and on the right one done in the iMacs own ColourSynch Utility.

In the left image the RED gamut projection is the new Colormunki v1.2.1 profile. This also corresponds to the white mesh grid in the Colour Synch image.

Now the smaller WHITE gamut projection was produced with an i1Pro 2 using the maximum number of calibration colours; this corresponds to the coloured projection in the Coloursynch window image.

The GREEN gamut projection is the supplied iMac system monitor profile – which is slightly “pants” due to its obvious smaller size.

What’s astonished me is that the Colormunki Photo with the new software v1.2.1 has produced a larger gamut for the display than the i1 Pro 2 did under Mountain Lion OSX 10.8

I’ve only done a couple of test prints via softproofing in Lightroom, but so far the new monitor profile has led to a small improvement in screen-to-print matching of the some subtle yellow-green and green-blue mixes, aswell as those yellowish browns which I often found tricky to match when printing from the iMac.

So, my advice is this, if you own a Colormunki Photo and have upgraded your iMac to Yosemite CHECK your X-Rite software version number. Checking for updates doesn’t always work, and the new 1.2.1 Mac version is well worth the trouble to install.

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Camera Calibration

Custom Camera Calibration

The other day I had an email fall into my inbox from leading UK online retailer…whose name escapes me but is very short… that made my blood pressure spike.  It was basically offering me 20% off the cost of something that will revolutionise my photography – ColorChecker Passport Camera Calibration Profiling software.

I got annoyed for two reasons:

  1. Who the “f***” do they think they’re talking to sending ME this – I’ve forgotten more about this colour management malarkey than they’ll ever know….do some customer research you idle bastards and save yourselves a mauling!
  2. Much more importantly – tens of thousands of you guys ‘n gals will get the same email and some will believe the crap and buy it – and you will get yourselves into the biggest world of hurt imaginable!

Don’t misunderstand me, a ColorChecker Passport makes for a very sound purchase indeed and I would not like life very much if I didn’t own one.  What made me seethe is the way it’s being marketed, and to whom.

Profile all your cameras for accurate colour reproduction…..blah,blah,blah……..

If you do NOT fully understand the implications of custom camera calibration you’ll be in so much trouble when it comes to processing you’ll feel like giving up the art of photography.

The problems lie in a few areas:

First, a camera profile is a SENSOR/ASIC OUTPUT profile – think about that a minute.

Two things influence sensor/asic output – ISO and lens colour shift – yep. that’s right, no lens is colour-neutral, and all lenses produce colour shifts either by tint or spectral absorption. And higher ISO settings usually produce a cooler, bluer image.

Let’s take a look at ISO and its influence on custom camera calibration profiling – I’m using a far better bit of software for doing the job – “IN MY OPINION” – the Adobe DNG Profile Editor – free to all MAC download and Windows download – but you do need the ColorChecker Passport itself!

I prefer the Adobe product because I find the ColorChecker software produced camera calibration profiles there were, well, pretty vile in terms of increased contrast especially; not my cup of tea at all.

camera calibration, Andy Astbury, colour, color management

5 images shot at 1 stop increments of ISO on the same camera/lens combination.

Now this is NOT a demo of software – a video tutorial of camera profiling will be on my next photography training video coming sometime soon-ish, doubtless with a somewhat verbose narrative explaining why you should or should not do it!

Above, we have 5 images shot on a D4 with a 24-70 f2.8 at 70mm under a consistent overcast daylight at 1stop increments of ISO between 200 and 3200.

Below, we can see the resultant profile and distribution of known colour reference points on the colour wheel.

camera calibration, Andy Astbury, colour, color management

Here’s the 200 ISO custom camera calibration profile – the portion of interest to us is the colour wheel on the left and the points of known colour distribution (the black squares and circled dot).

Next, we see the result of the image shot at 3200 ISO:

camera calibration, Andy Astbury, colour, color management

Here’s the result of the custom camera profile based on the shot taken at 3200 ISO.

Now let’s super-impose one over t’other – if ISO doesn’t matter to a camera calibration profile then we should see NO DIFFERENCE………….

camera calibration, Andy Astbury, colour, color management

The 3200 ISO profile colour distribution overlaid onto the 200 ISO profile colour distribution – it’s different and they do not match up.

……..well would you bloody believe it!  Embark on custom camera calibration  profiling your camera and then apply that profile to an image shot with the same lens under the same lighting conditions but at a different ISO, and your colours will not be right.

So now my assertions about ISO have been vindicated, let’s take a look at skinning the cat another way, by keeping ISO the same but switching lenses.

Below is the result of a 500mm f4 at 1000 ISO:

camera calibration, Andy Astbury, colour, color management

Profile result of a 500mm f4 at 1000 ISO

And below we have the 24-70mm f2.8 @ 70mm and 1000 ISO:

camera calibration, Andy Astbury, colour, color management

Profile result of a 24-70mm f2.8 @ 70mm at 1000 ISO

Let’s overlay those two and see if there’s any difference:

camera calibration, Andy Astbury, colour, color management

Profile results of a 500mm f4 at 1000 ISO and the 24-70 f2.8 at 1000 ISO – as massively different as day and night.

Whoops….it’s all turned to crap!

Just take a moment to look at the info here.  There is movement in the orange/red/red magentas, but even bigger movements in the yellows/greens and the blues and blue/magentas.

Because these comparisons are done simply in Photoshop layers with the top layer at 50% opacity you can even see there’s an overall difference in the Hue and Saturation slider values for the two profiles – the 500mm profile is 2 and -10 respectively and the 24-70mm is actually 1 and -9.

The basic upshot of this information is that the two lenses apply a different colour cast to your image AND that cast is not always uniformly applied to all areas of the colour spectrum.

And if you really want to “screw the pooch” then here’s the above comparison side by side with with  the 500f4 1000iso against the 24-70mm f2.8 200iso view:

camera calibration, Andy Astbury, colour, color management

500mm f4/24-70mm f2.8 1000 ISO comparison versus 500mm f4 1000 ISO and 24-70mm f2.8 200 ISO.

A totally different spectral distribution of colour reference points again.

And I’m not even going to bother showing you that the same camera/lens/ISO combo will give different results under different lighting conditions – you should by now be able to envisage that little nugget yourselves.

So, Custom Camera Calibration – if you do it right then you’ll be profiling every body/lens combo you have, at every conceivable ISO value and lighting condition – it’s one of those things that if you don’t do it all then you’d be best off not doing at all in most cases.

I can think of a few instances where I would do it as a matter of course, such as scientific work, photo-microscopy, and artwork photography/copystand work etc, but these would be well outside the remit the more normal photographic practices.

As I said earlier, the Passport device itself is worth far more than it’s weight in gold – set up and light your shot and include the Passport device in a prominent place. Take a second shot without it and use shot 1 to custom white balance shot 2 – a dead easy process that makes the device invaluable for portrait and studio work etc.

But I hope by now you can begin to see the futility of trying to use a custom camera calibration profile on a “one size fits all” basis – it just won’t work correctly; and yet for the most part this is how it’s marketed – especially by third party retailers.

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The ND Filter

Long Exposure & ND Filters

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

A view of the stunning rock formations at Porth Y Post on the Welsh island of Anglesey. The image is a long exposure of very rough sea, giving the impression of smoke and fog.  30 seconds @f13 ISO 100. B&W 10stop ND – unfiltered exposure would have been 1/30th.

The reason for this particular post began last week when I was “cruising” a forum on a PoD site I’m a member of, and I came across a thread started by someone about heavy ND filters and very long exposures.

Then, a couple of days later a Facebook conversation cropped up where someone I know rather well seemed to be losing the plot over things totally by purchasing a 16 stop ND.

The poor bugger got a right mauling from “yours truly” for the simple reason that he doesn’t understand the SCIENCE behind the art of photography.  This is what pisses me off about digital photography – it readily provides “instant gratification” to folk who know bugger all about what they are doing with their equipment.  They then spend money on “pushing the envelope” only to find their ivory tower comes tumbling down around them because they THOUGHT they knew what they were doing………..stop ranting Andy before you have a coronary!

OK, I’ll stop “ranting”, but seriously folks, it doesn’t matter if you are on a 5DMkIII or a D800E, a D4 or a 1Dx – you have to realise that your camera works within a certain set of fixed parameters; and if you wander outside these boundaries for reasons of either stupidity or ignorance, then you’ll soon be up to your ass in Alligators!

Avid readers of this blog of mine (seemingly there are a few) will know that I’ve gone to great lengths in the past to explain how sensors are limited in different ways by things such as diffraction and that certain lens/sensor combinations are said to be “diffraction limited; well here’s something new to run up your flag pole – sensors can be thought of as being “photon limited” too!

I’ll explain what I mean in a minute…..

SENSOR TYPE

Most folk who own a camera of modern design by Nikon or Canon FAIL at the first hurdle by not understanding their sensor type.

Sensors generally fall into two basic types – CCD and CMOS.

Most of us use cameras fitted with CMOS sensors, because we demand accurate fast phase detection AF AND we demand high levels of ADC/BUFFER speed.  In VERY simplistic terms, CCD sensors cannot operate at the levels of speed and efficiency demanded by the general camera-buying public.

So, it’s CMOS to the rescue.  But CMOS sensors are generally noisier than CCDs.

When I say “noise” I’m NOT referring to the normal under exposure luminance noise that a some of you might be thinking of. I’m talking about the “background noise” of the sensor itself – see post HERE .

Now I’m going to over simplify things for you here – I need to because there are a lot of variables to take into account.

  • A Sensor is an ARRAY of PHOTOSITES or PHOTODIODES
  • A photodiode exists to do one thing – react to being struck by PHOTONS of light by producing electrons.
  • To produce electrons PROPORTIONAL to the number of photons that strike it.

Now in theory, a photodiode that sees ZERO photons during the exposure should release NO ELECTRONS.

At the end of the exposure the ADC comes along and counts the electrons for each photodiode – an ANALOGUE VALUE – and converts it to a DIGITAL VALUE and stores that digital value as a point of information in the RAW file.

A RAW converter such as Lightroom then reads all these individual points of information and using its own in-built algorithms it normalises and demosaics them into an RGB image that we can see on our monitor.

Sounds simple doesn’t it, and theoretically it is.  But in practice there’s a lot of places in the process where things can go sideways rapidly……..!

We make a lot of assumptions about our pride and joy – our newly purchased DSLR – and most of these assumptions are just plain wrong.  One that most folk get wrong is presuming ALL the photodiodes on their shiny new sensor BEHAVE IN THE SAME WAY and are 100% identical in response.  WRONG – even though, in theory, it should be true.

Some sensors are built to a budget, some to a standard of quality and bugger the budget.

Think of the above statement as a scale running left to right with crap sensors like a 7D or D5000 on the left, and the staggering Phase IQ260 on the right.  There isn’t, despite what sales bumph says, any 35mm format sensor that can come even close to residing on the right hand end of the scale, but perhaps a D800E might sit somewhere between 65 and 70%.

The thing I’m trying to get at here is that “quality control” and “budget” are opposites in the manufacturing process, and that linearity and uniformity of photodiode performance costs MONEY – and lots of it.

All our 35mm format sensors suffer from a lack of that expensive quality control in some form or other, but what manufacturers try to do is place the resulting poor performance “outside the envelope of normal expected operation” as a Nikon technician once told me.

In other words, during normal exposures and camera usage (is there such a thing?) the errors don’t show themselves – so you are oblivious to them. But move outside of that “envelope of normal expected operation” and as I said before, the Alligators are soon chomping on your butt cheeks.

REALITY

Long exposures in low light levels – those longer than 30 to 90 seconds – present us with one of those “outside the envelope” situations that can highlight some major discrepancies in individual photodiode performance and sensor uniformity.

Earlier, I said that a photodiode, in a perfect world, would always react proportionally to the number of photons striking it, and that if it had no photon strikes during the exposure then it would have ZERO output in terms of electrons produced.

Think of the “perfect” photodiode/photosite as being a child brought up by nuns, well mannered and perfectly behaved.

Then think of a child brought up in the Gallagher household a la “Shameless” – zero patience, no sense of right or wrong, rebellious and down right misbehaved.  We can compare this kid with some of the photodiodes on our sensor.

These odd photodiodes usually show a random distribution across the sensor surface, but you only ever see evidence of their existence when you shoot in the dark, or when executing very long exposures from behind a heavy ND filter.

These “naughty” photodiodes behave badly in numerous ways:

  • They can release a larger number of electrons than is proportional to their photon count.
  • They can go to the extreme of releasing electrons when the have a ZERO photon count.
  • They can mimic the output of their nearest neighbors.
  • They can be clustered together and produce random spurious specks of colour.

And the list goes on!

It’s a Question of Time

These errant little buggers basically misbehave because the combination of low photon count and overly long exposure time allow them to, if you like, run out of patience and start misbehaving.

It is quite common for a single photodiode or cluster of them to behave in a perfect manner for any shutter speed up to between 30 seconds and 2 minutes. But if we expose that same photodiode or cluster for 3 minutes it can show abnormal behavior in its electron output.  Expose it for 5 minutes and its output could be the same, or amplified, or even totally different.

IMPORTANT – do not confuse these with so-called “hot pixels” which show up in all exposures irrespective of shutter duration.

Putting an ND filter in front of your lens is the same as shooting under less light.  Its effect is even-handed across all exposure values in the scenes brightness range, and therein lies the problem.  Cutting 10 stops worth of photons from the highlights in the scene will still leave plenty to make the sensor work effectively in those areas of the image.

But cutting 10 stops worth of photons from the shadow areas – where there was perhaps 12 stops less to begin with – might well leave an insufficient number of photons in the very darkest areas to make those particular photodiodes function correctly.

Exposure is basically a function of Intensity and Time, back in my college days we used to say that Ex = I x T !

Our ND filter CUTS intensity across the board, so Time has to increase to avoid under exposure in general.  But because we are working with far fewer photons as a whole, we have to curb the length of the Time component BECAUSE OF the level of intensity reduction – we become caught in a “Catch 22” situation, trying to avoid the “time triggered” malfunction of those errant diodes.

Below is an 4 minute exposure from behind a Lee Big Stopper on a 1Dx – click on both images to open at full resolution in a new window.

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

Canon 1Dx
4 minutes @ f13
ISO 200 Lee 10stop

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

The beastly Nikon D800E fairs a lot better under similar exposure parameters, but there are still a lot of repairs to be done:

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

A 4 minute exposure on a D800, f11 at 200ISO

Most people use heavy ND filters for the same reason I do – smoothing out water.

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

The texture of the water in the top shot clutters the image and adds nothing – so get rid of it! D4,ISO 50, 30secs f11 Lee Big Stopper

Then we change the camera orientation and get a commercial shot:

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

Cemlyn Bay on the northwest coast of Anglesey, North Wales, Approximately 2.5 km to the east is Wylfa nuclear power station. Same exposure as above.

In this next shot all I’m interested in is the jetty, neither water surface texture or horizon land add anything – the land is easy to dump in PShop but the water would be impossible:

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

I see the bottom image in my head when I look at the scene top left. Again, the 10 stop ND fixes the water, which adds precisely nothing to the image. D4 ISO 50, 60 secs, f14 B&W 10 stop

The mistake folk make is this, 30 seconds is usually enough time to get the effect on the water you want, and 90 to 120 seconds is truly the maximum you should ever really need.  Any longer and you’ll get at best no more effect, and at worst the effect will not look as visually appealing – that’s my opinion anyway.

This time requirement dovetails nicely with the “operating inside the design envelope” physics of the average 35mm format sensor.

So, as I said before, we could go out on a bit of a limb and say that our sensors are all “photon limited”; all diodes on the sensor must be struck by x number of photons.

And we can regard them as being exposure length limited; all diodes on the sensor must be struck by x photons in y seconds in order to avoid the pitfalls mentioned.

So next time you have the idea of obtaining something really daft, such as the 16 stop ND filter my friend ordered, try engaging your brain.  An unfiltered exposure that meters out at 1/30th sec will be 30 seconds behind a 10 stop ND filter, and a whopping 32 minutes behind a 16 stop ND filter.  Now at that sort of exposure time the sensor noise in the image will be astonishing in both presence and variety!

As I posted on my Book of Face page the other day, just for kicks I shot this last Wednesday night:

long exposure,slow shutter speed,ND filter,CMOS sensor,noise

Penmon Lighthouse in North Wales at twilight.
Sky is 90 secs, foreground is 4 minutes, D4, f16, ISO 50 B&W 10 stop ND filter

The image truly gives the wrong impression of reality – the wind was cold and gusting to 30mph, and the sea looked very lumpy and just plain ugly.

I spent at least 45 minutes just taking the bloody speckled colour read noise out of the 4 minute foreground exposure – I have to wonder if the image was truly worth the effort in processing.

When you take into account everything I’ve mentioned so far plus the following:

  • Long exposures are prone to ground vibration and the effects of wind on the tripod etc
  • Hanging around in places like the last shot above is plain dangerous, especially when it’s dark.

you must now see that keeping the exposures as short as possible is the sensible course of action, and that for doing this sort of work a 6 stop ND filter is a more sensible addition to your armoury than a 16 stop ND filter!

Just keep away from exposures above 2 minutes.

And before anyone asks, NO – you don’t shoot star trails in one frame over 4 hours unless you’re a complete numpty!  And for anyone who thinks you can cancel noise by shooting a black frame think on this – the black frame has to be shot immediately after the image, and has to be the same exposure duration as the main image.  That means a 4 hour single frame star trail plus black frame to go with it will take at least 8 hours – will your camera battery last that long?  If it dies before the black frame is finished then you lose BOTH frames……………

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Exposure Compensation

Exposure Compensation

Exposure Compensation – that’s something else that cropped up once or twice for the chaps on my recent Norwegian Eagle workshop!

We had something like 420 or more dives from eagles during the trip, and very few if any were shot with flat metering, or 0Ev compensation.

What is Exposure Compensation, and why do we need to use it?

It all begins with this little button:

Exposure Compensation,exposure

D3 Exposure Compensation button – Nikon, Canon and most others use the same symbol.

Pushing this button and rotating your main command dial will select a certain exposure compensation value.

Why do we need to use Exposure Compensation though?

Cameras, for all their complexity and “intelligent whotsits” are basically STUPID!  They don’t know WHAT you are trying to photograph, or HOW you are trying to photograph it.

They make a lot of very basic assumptions about what you are trying to do – 99.99% of which are WRONG!

The camera does NOT know if you are trying to photograph:

  • A white cat in a coal shed
  • A black cat in a snow storm
  • A white cat in a snow storm
  • A black cat in a coal shed

All it sees is a frame full of various amounts of light and shade, and depending on your metering mode (which should always be Matrix/Evaluative – see post here) it gives you an “average mean exposure value”.

Take a general scene of fairly low contrast under flat overcast light:

exposure compensation,exposure,metering

A scene as WE see it.

exposure compensation,exposure,metering

The same scene as the camera METER sees it.

exposure compensation,exposure,metering

Lighter tones within the scene.

exposure compensation,exposure,metering

Some darker area tones within the scene.

exposure compensation,exposure,metering

The exposure is governed by the PREDOMINANT tone.

As discussed in the previous metering article mentioned earlier, only MATRIX/EVALUATIVE takes the entire frame area into account.

Okay, so that scene was fairly bland on the old tonal front, so let’s have a look at something a little more relevant:

exposure compensation,exposure,metering

Straight off the camera with no processing. 1/2000th @ f4 1600ISO +1.3Ev

exposure compensation,exposure,metering

As the camera metered the scene WITHOUT compensation.

Why would the image be so dark and under exposed?

Well here’s an approximation of the cameras average tone “thought process”:

exposure compensation,exposure,metering

The approximate average value of the scene.

But if we look at some averages WITHIN the overall image:

exposure compensation,exposure,metering

Random tonal averages within the image.

We can see that the tonal values for the subject are generally darker than the average scene value, therefore the camera records those values as “under exposed”.

This is further compounded by the cameras brain making the decision that the commonest tonal value MUST represent “mid grey” – which it DOESN’T; it’s lighter than that – and so under exposing the image even further!

Now I’m not going to get into the argument about “what is mid grey” and do Nikon et al calibrate to 12%, 18%, 20% or whatever – to be honest it’s “neither here nor there” from our standpoint.

What is CRITICAL though is that we understand the old adage:

“Light Subject Dark Background = Under, or negative exposure compensation. And that Dark Subject Light Background = Over, or positive exposure compensation”.

Okay, but what are we actually doing?

In any exposure mode other than Manual mode, we are allowing the camera to meter the scene AND make the decision over which shutter speed or aperture to use depending on whether we have the camera in Av or Tv mode – that’s Canon-speak for A or S on Nikon.

If we are in shutter priority/S/Tv mode then the camera sets the aperture to give us its metered exposure – that thing that’s usually WRONG! – at the shutter speed we’ve selected.

If, as in the case above, we ADD +1.3Ev – one and one third stops of POSITIVE exposure compensation, the camera uses the shutter speed we’ve selected but then opens up the aperture WIDER than it’s “brain” wants it to.

How wide? 1.3 stops wider, thus allowing 1.3 stops more light into the the sensor during the exposure time.

If we were in Av/A or aperture priority mode then it’s the shutter speed that would take up the slack and become 1.3 stops SLOWER than the cameras “brain” wanted it to be.

Here’s an example of negative exposure compensation:

exposure compensation,exposure,metering

1/3200th @ f4.5 1000ISO -1.3Ev exposure compensation.

In this particular shot we’re pointing towards the sun – a “dark subject, light background” positive exposure compensation scenario, or so you’d think.

But I want to “protect” those orange highlights in the water and the brightest tones in the eagle, so if I “peg those highlights” just over a stop below the top end of the cameras’  tonal response curve then there is no way on earth they are going to “blow” in the final RAW file.

Manual Exposure mode can still furnish us with exposure compensation based on metering if we engage AUTO-ISO.  If we decide we want to shoot continuously with a high shutter speed and a set aperture at a fixed ISO then our exposures are going to be all over the place.  But if we engage AUTO-ISO and let the camera choose the ISO speed via the meter reading, we can use the exposure compensation adjustments just the same as we do in Av or Tv modes.

This get’s us away from the problem of fixed ISO Tv mode running out of aperture in low light or when very high shutter speeds are needed; or conversely, stopping the aperture down too far when the sun comes out! – I’ll do a breakdown on this method of shooting later in the year – it’s not without it’s problems.

Next time you get the chance to stand by a large lake or other body of water, just take a moment to notice that the water is dark in some places and light in others. ambient light falling on a moving subject can easily be very uniform and so the subject basically has the same exposure value all the time.  But it’s the changing brightness of the background as the subject moves across it that causes us to need exposure compensation.

People seem to think there’s some sort of “magic” at play when they come out with me and I’m throwing exposure compensation values at them.  But there’s no magic here folks, just an ability to see beyond “the subject, framing etc” and to actually “see the light” and understand it.

After all, when we click our shutters we are imaging light – the subject is, for the most part, purely incidental!

And there’s only one way you can learn to see light and grasp its implications for camera exposure, and that’s to practice.

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Auto Focus Work Out

Auto Focus Work Out

My recent summer trip to Flatanger in Norway, and to the famous “Eagle Man of Norway” Ole Martin Dahle, proved, as ever, a severe test of the auto focus capabilities of the gear!

We had 4 guys on the trip, 3 Nikon and 1 Canon, and White-tailed Eagles doing more than 40mph and turning on a dime is one of the hardest tests for auto focus tracking and lock on that you can imagine – especially when it’s all done hand held from a boat that’s rolling around in the sea swell.

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings

The Guys – yours truly, Malcolm Clayton and Paul Atkins; and Mohamed El Ashkar (all the way from Cairo!) and our Cambridge “Don” – all trips should have one – Jamie Gundry. Photo by Ole Martin Dahle.

We had a conglomeration of D4’s, D800E’s and 200-400 f4’s, with a smattering of 300mm and 400mm f2.8’s – and then there was Mohamed with his solitary 1Dx and 300 f2.8.

And our target:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings

Say “Hello” to “Brutus” – an eagle who lives up to his name for sure – a total brute, especially to a boat full of daft photographers! CLICK for larger view.

Just to set the scene with regard to the technical side of things; birds fly into the wind given the choice, and the sun is wherever it decides to be! So the boat driver – Ole – always needs to position the boat so that “wind and sunlight” are coming from pretty much the same direction, otherwise the birds are not front-lit and cast their own shadows across themselves. In other words the images look like crap!

Some birds come towards the boat, take the fish and then turn away; some will do their approach parallel to the boat; and gits like Brutus will fly low and fast straight at you, pick the fish and then turn straight for the boat and climb.

But no matter how they choose to approach the camera boat all the birds pick the fish and go back to where they’ve come from.

Ole has intimate knowledge of these birds as individuals, and so has a damn good idea of what they will do as they come to the boat.  This enables him to manoeuvre the boat for the best shots, and this skill is what you pay for.

Perhaps by now you’ve got the general feel for the situation – a boat that’s subject to wave motion and which might suddenly go backwards 10 yards through its own wake – not the steadiest of camera platforms!

Couple that with trying to make the auto focus lock on and track the bird, and maintain a modicum of composition – it’s just damned hard work.

Photographing anything that’s moving is hard work; moving erratically is even harder; and hand holding on an oscillating camera platform makes the job beyond hard.  This style of shooting will NEVER yield vast rafts of sharp sequential images – anyone who tells you different is an outright liar. Christ, even licensed FIA F1 ‘togs are on “easy street” by comparison.

Auto focus cannot be set up perfectly for this sort of situation, but understanding it is a MUST if you want to maximise the opportunity.

Auto Focus Choices

There are 3 main things that control the effectiveness of auto focus and AF tracking:

AF Area Mode

AF Tracking Lock-on interval

Frame Rate

(Bare in mind I’m talking Nikon here, but sorting Mohameds’ 1Dx out showed my that Canon AF is pretty much the same).

Now I dealt with the latter in a previous post HERE and so we need to concentrate here on AF area modes in the main.

Let’s look at what we have to work with on a Nikon body – in this case a D4:

Firstly, the AF sensor layout.

All 51 focus sensors, and there approximate layout in relation to the image frame:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings

All 51 of the Nikon Multi Cam 3500 FX focus sensors – both cross and linear sensors depicted.

Just the Cross-type Sensors:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

The 15 Cross type focus sensors on the Nikon Multi-Cam 3500 FX unit.

The Linear-type Sensors:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

The 36 Linear type focus sensors on the Nikon Multi-Cam 3500 FX unit.

Single Area AF

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

Single Area, or single point AF.

9 Point Dynamic Area AF:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

9 Point Dynamic Area AF

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

9 Point DA AF as displayed in the viewfinder (drop shadows added in Photoshop behind the dots to aid visibility in this article).

21 Point Dynamic Area AF:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

21 Point Dynamic Area AF

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

21 Point DA AF as displayed in the viewfinder (drop shadows added in Photoshop behind the dots to aid visibility in this article).

51 Point Dynamic Area AF:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

51 Point DA AF as displayed in the viewfinder (drop shadows added in Photoshop behind the dots to aid visibility in this article).

As a stills photographer you are using what’s called Phase Detection auto focus (that’ll be another blog post topic!) but it still relies on a mix of contrast,luminosity and colour to work out what it should be concentrating on in the frame.

Consider the following 2 images, A & B:

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

A. Dark Subject and Light Background.
Subject itself is low contrast, background water is higher contrast. Subject is at 15 meters, Focal Length is 240mm

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

B. Light Subject against a Dark Background.
Subject now has a slightly higher contrast, and background is lower contrast. Subject 29 meters, Focal length 360mm

Auto focus is dumb; just plain stupid, left to its own devices.  It, like me (yep, me dumb too!) favours lighter things with a higher degree of contrast.  The lighter something is then the brighter and more saturated it colour is, and this in turn gives it higher localised contrast.

Auto focus will be happier locking on to and tracking Eagle B than Eagle A.

In A, the AF will want to switch to the lighter, more contrasty water behind the bird – unless of course you “hobble it” and stop it from doing so…

And you stop it by BLINDING IT – in other words use LESS active auto focus points!

“If it ain’t got ’em it can’t switch to ’em!”

If all the AF points in use are on the important part of the subject (the EYE in this case) then there’s little or no chance of the auto focus switching to somewhere you don’t want it to go to.

In a perfect world we’d all be using Single Area AF on a tripod and panning away quite happily keeping that single sensor on the targets eye……………oh I wish!!!!!!

51 point AF is out for this sort of work – with what I’ve just written you should now easily understand why.

So we are down to either the 9 point or 21 point Dynamic Areas.

It all comes down to two things:

  • How steady you can keep the camera.
  • How big in the frame the birds are – in other words, subject distance.

But accuracy of auto focus will always be improved by using the least number of sensors you can get away with.

 

Image A. is at 240mm and a subject distance of 15 meters, and Image B. is at 360mm and a subject distance of 29 meters.  Both images were shot using 21 point Dynamic Area AF, 1/2000th @ f7 and 1600ISO.

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

21 point AF, 15 meters and 240mm focal length.

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

21 point AF, 29 meters and 360mm focal length.

On the upper detail image there’s one, perhaps two of the 21 sensors that are NOT on the subject.

On the second image there are at least 9 sensors out of the 21 in the group that are NOT on the bird.

If the bird in image A. had been 29 meters away I’ll guarantee it would have been out of focus – why?

  • Lack of good directional light.
  • Poor subject contrast and illumination.
  • Brighter, higher contrast background.
  • More sensors “Off Target”.

And the auto focus hasn’t wanted to wander to the background on image B. because there’s nothing there for it to favour over the main subject.

How Dynamic Area AF Works

9 point DA auto focus uses the single AF point that you select, but activates the 8 points surrounding it.  If you, or the subject, or both, move so that the single point you selected comes “off target” then one of those 8 surrounding points will “cover” the error and maintain focus lock and tracking until you get back on target.

In 9 point DA, auto focus ALL the sensors activated are “cross type” sensors, assuming you use a sensor on the vertical center line of the AF grid.

In 21 point DA, auto focus is still centered on the single sensor you select, but now the surrounding 20 are activated. But at least 6 of these sensors will be linear, not cross type sensors.

Auto Focus Senor Types – Cross and Linear (line).

This is going to be immensely paraphrased!

AF sensors need to see edge detail in order to work. A linear sensor can work more effectively when the edge it’s looking at is perpendicular to it.

The more an edge is parallel to said line sensor then the harder time it has in discerning when said edge is sharp or not.

But if we add 2 line sensors together at right angles to each other, then an edge that is parallel to one line is perpendicular to the other – so edge detection is greatly enhanced.

In an ideal scenario 9 point Dynamic Area AF, centered in the middle of the view finder and kept on the eagles head would be the ideal way to go, but with the other circumstances of:

  • Moving camera platform
  • Potential closeness of subject (sub 15 meters possible)

then 9 point DA might be a wee bit tight on both counts, and 21 point makes more sense from a tracking and shooting perspective.

But it leads to an initial problem with the auto focus acquiring the target in the first place.  You have to pick these eagles up quite a way out, and if one is coming low to the water then there is possibly too much in the frame to act as a distraction to the auto focus unit itself; though this isn’t quite such an issue if the bird is high in the sky.

So my recommendation for any form of bird-in-flight photography is to start out at 9 point DA and see how you get on!

There is always the AF Tracking Lock On feature that you can deploy in order to “hobble” the AF unit from switching  to subjects closer to or further away, but if I’m honest I find this the most sticky and difficult aspect of the Nikon system to get a precise handle on.  It does exactly “what it says on the tin” but it’s the “when” and “how much by” bits that have me slightly guessing.

Sometimes I put it on long and it basically waits for perhaps 4 or 5 seconds before it tries to switch focus, while at other times it does so in less than half the time.  Sometimes I feel it actually diminishes the effectiveness of the “predictive” side of the auto focus tracking unit.

But if I turn it off when hand holding the camera for flight shots then everything turns to crap – so I turn it back on again!

Again, my base recommendations for this are SHORT to NORMAL and see how things go.

One thing that can have a considerable impact on the way you perceive your auto focus effectiveness is how you have your AF release priority set up (CS a1).

There are 4 options:

  • Release
  • Focus+Release
  • Release+Focus
  • Focus

By default this is set to FOCUS.  With the default setting, it’s theoretically impossible to take a soft shot.  But in practice that’s not so simple, and I’ve taken many a soft shot when the D4 “thinks” things are sharp; though in the main, that seems to have been cured the minute we got trap focus back with the latest firmware upgrade.

Release means the camera will take shots irrespective of focus being acquired or not.  I NEVER use this option.

Focus+Release means that the first frame will only be taken once focus is acquired, and subsequent frames will be taken irrespective of focus.  This is one of my preferred options when everything is unstable – that first frame hopefully sets up the auto focus and AF tracking and so everything SHOULD keep the subsequent frames sharp – please note the use of the word “should”!

Both the above release priority modes do NOT slow the frame rate.

Release+Focus – works the opposite way to Focus+Release – it does slow the frame rate down giving the mirror more down-time and so the auto focus system has more time to work.  This is my other preferred option, the one I use when the “action” may not be as repeatable.

Focus – This is the option I deploy when shooting from a tripod or when the action is not quite so fast-paced.  Again, this option slows the frame rate.

The Back Button Auto Focus Option

I always use the back button for auto focus activation.  There are plenty of arguments for doing this, but I just feel it’s darn right more efficient than having AF activation on the shutter button.  Just don’t forget to turn AF/Shutter ON to OFF in the menu, otherwise you are just wasting time and effort!

Conclusion

A lot of folk feel that their auto focus is flawed; but more often it is they and their setup choices which are flawed.

There is no blanket panacea or magic bullet setting for your AF system – as with everything else you have to constantly evaluate the light around you, anticipate the shot and make the necessary changes to setup – otherwise it’s going to be a sad day.

But knowing how your gear works and how it reacts under different scenarios is the “meat and two veg” of good photography.  Couple that with shot anticipation and the proper corrective measures and it’s off home for tea and medals!

But above all, remember to have a laugh – you’re a long time dead……..

wildlife photography,auto focus,Nikon,D4,Andy Astbury,eagle,Norway,workshop,camera settings,Nikon Multi-Cam 3500 FX unit

“GIMME SOME, YOU MEAN BARSTARD!”

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Black Ink Type

Black ink type and black ink switching when moving from matte to luster and gloss papers – here’s my thoughts on this, initially triggered by Franks’ reply to my previous article HERE.

And I quote:

Another great and instructive article Andy. I have the r3000 but get slightly annoyed with the black ink changes from one to the other. Some further guidance on the use of these re paper ‘types’ would be appreciated by moi ~ please ♡

Look, he’s even put a heart in there – bless you Frank, that’s more than I’ve got out of ‘her indoors’ for years!

Now the basic school of thought over this switching of black ink type is this:

  • PK, or Photo Black ink type supposedly produces a smooth, highly glossy black.
  • MK or Matte Black ink type produces a dull, flat black.
  • Using a matte finish paper requires the MATTE black ink type.
  • Using Luster or Gloss paper requires the Photo black ink type.

The PK black ink type really only produces a HIGH GLOSS finish when chucked onto HIGH GLOSS media.  Its’ got a rather less glossy and more ‘egg shell’ finish when used on a more luster finish paper. There does come a “tipping point” though where it will look a little shinier than the finish of the paper – and it’s this tipping point where theory, clever-dicks and user-guides tell you there’s a need to switch to the matte black ink type.

The Matte black ink type does exactly what point two says it does.

The third point – replace the word “requires” with the phrase “can cope with” and we’d be about right.

The forth point is absolutely true; get this wrong by printing with the MK black ink type on high gloss paper and you’ll just waste consumables and potentially end up with the type of clean up operation normally the preserve of Exon & BP. Dot gain on steroids!

There’s also an argument that the MK black ink type produces a deeper black on matte finish paper than the PK black ink type – this is also true:

printing,black ink,profile,icc profile,black ink type,matte finish,gloss finish,luster finish,

Permajet canned profiles for Museum paper on the Epson 4800 printer using PK and MK black ink types.

As we can clearly see, the Matte black ink type does indeed accommodate a deeper black point than its counterpart Photo black ink type.

Adopting the Common Sense Approach

There are a few things we need to think about here, and the first one is my constant mantra that the choice of paper is governed by the “overall look, feel and atmosphere of the finished image” when it’s sitting there on your monitor.

Paper choice IS the final part of the creative process; for all the reasons I’ve mentioned in past blog posts.

You will also know by now that in my world there is little room for high gloss paper – it’s a total pain the bum because of its highly reflective surface; but that same surface can allow you to print the very finest of details.

But here’s common sense point number 1 – the majority of people reading this blog, attending my workshops and coming to me for 1to1 tuition CAN NOT produce images with detail fine enough to warrant this single benefit of high gloss paper.

That’s not because they’re daft or rubbish at processing either – it’s simply due to the fact that they shoot 35mm format dSLR, not £30K medium format.  The sensors we commonly use can’t record enough ultra fine detail.  There’s a really good comparison between the Nikon D800 and an IQ160 here, it’s well worth having a look – then you’ll see what I’m on about.

The point I’m trying to make is this; print on gloss from 35mm if you like; but you are saddling yourself with its problems but not truthfully getting any of the benefit – but you can kid yourself if you like!

I Lust After Luster Papers But How Lusty Is That Luster?

As I mentioned in the previous post, Calumet Brilliant Museum Satin Matte Natural is NOT a matte finish paper.

True matte papers never really hold much appeal for me if I’m honest, because they are very dull, flat and relatively lifeless.  Yes, a 12×12 inch monochromatic image might look stunning, especially hanging in an area where reflections might prove difficult for any other print surface.

But that same image printed 8 foot square might well “kill’ any room you hang it in, just because it’s so dull and so damned BIG.

True matte papers do have their uses that’s for sure, but in the main you need to discriminate between matte and what I call matte “effect”.

Permajet Fine Art Museum 310, Matte Plus and Portrait 300 are papers that spring to mind as falling into this matte effect category – and wouldn’t you know it, there are canned profiles for these papers for both PK and MK black ink type ink sets, as you can see from the image earlier in the post.

So, with regard to black ink type switching you have to ask yourself:

  • Am I using a paper the ACTUALLY NEEDS the MK black ink type?  Chances are you’re probably not!
  • If I am, do I really want to – how big a print am I doing?

In my own print portfolio I only have two images that benefit from being printed on a “dead” media surface, and they are both printed to Permajet Museum using the PK black ink type.

I had another one that looked “nearly there” but the heavy texture of the paper detracted from the image, so it was re-proofed and printed to Matt Plus, again using PK ink. It looked just the same from a colour/luminance stand point, but worse from a ‘style’ point because of the zero texture.

Along comes Calumet Museum Satin Matte Natural!

The subtle texture gets me where I wanted to be on that score, and that ever-so-soft luster just makes the colours come to life that tiny bit more, giving me a print variation that I love and hadn’t even envisaged at the time I did the original print.

Ink Type Switching

I have to say at the outset that I do NOT own an R3000 printer – I use wide format Epson printers and so have no commercial need for the 3000 DT format.  But I always advise people looking for a printer to buy one – it’s a stunning machine that punches well above it’s weight based on price point.

My Epson wide format does not hold both black ink types.  Switching entails a rather tedious and highly wasteful process; which I have neither desire or need to embark upon.

But if you have any brand of printer that carries both types on board then I’d highly recommend you to set the black ink type to PK, and turn any auto-switching OFF – that is, set switching to manual.

Right, now the super-pessimist in me shines through!

I’m not a fan of Epson papers on the whole, and there’s a lot more choice and far better quality available from third party suppliers ranging from Photospeed to Hahnemuhle, Canson, Red River and all points in between.

Now third party suppliers in the main will tell you to use one black ink type or the other – or either, and give you the correct media settings (Brilliant – are you reading this??).

But, if you have auto switching enabled, and use Epson paper, the print head sees the paper surface and automatically switches the ink to the ‘supposed’ correct type.  This switching process requires the printer to purge the black ink line and refill it with the ‘correct’ black ink type before printing commences.

Now these figures are the stats quoted from Epson:

Black ink conversion times:

  • Matte to Photo Black approx. 3 min. 30 sec
  • Photo to Matte Black approx. 2 min. sec

Ink used during conversion:

  • Matte to Photo Black approx. 3 ml
  • Photo to Matte Black approx. 1 ml

Now why the times and volumes aren’t the same in both directions is a bit of a mystery to me and doesn’t make sense.  But what is killer is that the carts are only 26 (25.9)ml and around £24 each, so 6 changes of black ink type is going to burn through as good as £25 of ink – and that’s without doing any bloody printing!!!

When ever I demo this printer at a workshop I never use Epson paper, auto switching is OFF and I never get a head sensor warning to tell me to switch ink even if I load Permajet Museum – the head sensor doesn’t warn me about the fact that I’m using PK ink.

Yes the printer could be up the spout, but using a canned PK profile the resulting print would tend to indicate otherwise.

Or something slightly more dark and sinister might be happening – or rather NOT, because I’m not using OEM paper………...What was that I heard you say?  Good gracious me…you might think that but I couldn’t possibly comment!

One thing to bare in mind is this.  For the most part, the majority of print media will work exceptionally well with the PK black ink type – BUT NOT THE OTHER WAY AROUND – you’ve been warned.  If you want to know how the captain of the Exon Valdez felt and be up to your ass in black stuff then go ahead and give it a try, but don’t send the cleaning bills to me!

I did it once years ago with an HP printer – I can still see matte black ink tide marks on the skirting board in my office……it wasn’t pretty! And it screwed the printer up totally.

Using PK on matte media will only effect the D-max and lower the overall contrast a wee bit; unless it’s a very low key image with vast areas of blackish tones in it then for the most part you’d perhaps struggle to notice it.  Sometimes you might even find that the drop in contrast even works to your advantage.

But don’t forget, you might not be using a matte media at all, even though it visually looks like it and says the word matte in the paper name.  If the paper manufacturer supplies a PK and an MK profile for the same paper then save yourself time and money and use the PK profile to soft-proof to AND to control the printer colour management.

Did that answer your question Frank – FRANK – can you hear me Frank??!!

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Flash Output Power

Flash output power raises a lot of questions when you are trying to decide how to spend your money.

A lot of people writing on the internet decry the versatility of portable speedlights and their use as studio-type lighting – something which is entirely wrong in my opinion; as there is nothing that can’t be done with them, as long as you have enough of them!

And you don’t have to take my word for it – just go and watch the worlds best exponent of the art, in my opinion anyway – Joe McNally. – then tell me if I’m wrong!

But with a top-of-the-line Nikon SB910 running at £340 and Canons new 600EXRT a cool £400 plus here in the UK, purchasing 10 to 15 of these puppies is a wallet-emptying proposition; though given the cash or sponsorship it’s the way I’d go all day long.

A lot of folk come to me with the same quandary – studio flash heads are a lot more cost-effective; notwithstanding their big limiting factor – lack of portability.

Leaving aside the other problems of many studio-style flash heads, namely lack of TTL and HSS/FP facility (though this can be walked-around on certain models with Pocket Wizards and the dark art of Hypersynch) they do give one big advantage – more photons for your buck.

But just how does one compare the flash output power of one unit/type with another – after all, this is what we want to know:

  • Can I get more light from flash A than I can from flash B
  • How many speedlights do I NOT have to buy if I get studio-style flash head C which costs 1.5x the price of one of my speedlights.

The problem is that manufacturers don’t make it easy to do direct comparisons of flash output power between brands and formats, and they tend to try and confuse the buyer with meaningless numbers and endless amounts of jargon.

Back in the days of manual-everything, we used to use flash in a very simple way using the units Guide Number.

The guide number is usually quoted as being at 100 ISO and at two values, one for metres and one for feet, and we use it with the following equation:

GUIDE No: = Distance x Aperture

So we might see a flash unit has a  guide number quoted as 40/131 at 100 ISO.  This means for example, that at 100 ISO and a flash to subject distance of 2.5 metres or 8.2 feet the correct aperture to use would be:

Guide No: divided by distance – in this case 40/2.5m or 131/8.2ft.

Either way the answer is 16, so we would set the shutter speed to the flash synch speed and the aperture to F16.

Simple!

Where things used to go a bit pear-shaped was when we introduced any form of output modifier such as a bounce board or diffuser because these spread and smooth the light and so reduce the number of photons falling on the subject by one or two stops.

But TTL flash metering soon put paid to all that grief.

Camera OEM Speedlights

Let’s compare a Nikon SB800 & SB910 – these have 100 ISO guide numbers of 38/125 & 34/112 respectively (published) – that’s right folks, the new one is weaker than the old one.

But by how much?

Well the old SB800 has a guide number that is 11.7% higher than the newer SB910, but what does this mean in terms of exposure value?

At a flash-to-subject distance of 3.4 metres, doing the maths says that our correct aperture would be 38/3.4 and 34/3.4 respectively. So the SB800 would put us at f11 (11.18 to be precise) while the SB910 would give us f10 – that’s an increase of over 1/3rd of a stop using the older unit.

When working with long lenses and wide apertures this extra 1/3rd of a stop gives me just that little bit more depth of field – and folk wonder why I don’t change mine!

Complications & Caveats

Nikon quote the two units above with guide numbers based on the head “zoom feature” being set to 35mm, which gives a fairly wide angle of lighting.  Someone said to me the other day that the new Canon 600EX was twice the power of the Nikon units I’ve already mentioned, simply because Canon quote the guide number for that device as a massive whopping 60!

The world is full of fools………..

Canon, in their infinite wisdom, quote that 60 value at a zoom head setting of 200mm.  The reality is that the guide number of this Canon unit varies between 26 with the zoom head at 20mm and 60 at 200mm – so in other words, give or take a bit, it’s pretty much in the same ball park as the Nikon units previously mentioned.

Canon speedlight naming policy tells you the units MAXIMUM guide number:

  • 600EX = 60 (metres)
  • 580EX = 58 (metres)
  • 550EX = 55 (metres)

The 550 specs also give you zoom length variations:

  • 105mm = 55 (metres)
  • 50mm = 42 (metres)
  • 17mm = 15 (metres)

Canon 600EX vs Nikon SB800 zoom lengths:

  • 105mm = 58 vs 56 (metres)
  • 50mm  = 42 vs 44 (metres)
  • 14mm = 15 vs 17 (metres)

Light leaves a flash unit in a cone of sorts, and the zoom heads on speedlight style units gather this cone of light so it basically matches the angle of view of the lens you are using and results in an efficient distribution of light across the image area – that’s the theory anyway.

Making the cone “tighter” forces the photons released by the flash into a more concentrated area, thus increasing the number falling on the subject and so increasing the overall exposure value.

So when we use guide numbers to compare various flash units we must ensure that we are comparing the units on a level playing field – in other words, the values we use are for the same “cone or reflector angle”.  And if the manufacturers use different reflector angles when assessing their flash guide numbers for promotion to the public, then you guys ‘n gals run the risk of being hood-winked into buying something that ain’t strictly what you thought it was when you ordered it.

So how do speed light style flash units stack up against studio type units?

Notwithstanding the lack of FP/HSS and any TTL metering problems, studio-type flash heads have guide numbers that are usually quoted as being “with standard reflector”.  This standard reflector is something which gathers those photons and shovels them out in a 50-55 degree spread; think “standard lens” on the image diagonal.

Current top end Nikon speed lights (and Canon) have guide numbers of sub 40 at 35mm reflector angles, and those equate to roughly 64 degrees diagonal coverage.  So if we were to “tighten them up” to 50 or 55 degrees we could, as a rough guide, round the guide numbers up to 42m or 44m.

Now we are on a more even playing field.

A Bowens Gemini 500R is quoted by Bowens as having a guide number of 85 with a standard reflector, so let’s be a bit cavalier with the numbers and say that it’s double the guide number of SB800/910 or 580EX etc.

So roughly how many speed lights is this puppy going to be equivalent to in terms of real flash output power ?

Hands up those who think two………….wrong!

This is where everything you thought you knew about exposure turns to shit in front of your very eyes (but not really!), and it’s called the Inverse Square Law.

Inverse Square Law

Now listen folks, this is as simple or as complicated as you care to make it!

When we capture a scene we capture a 2 dimensional plane filled with photons travelling towards us.

When we shine any light on an object we are actually throwing a flat sheet of light at it. This sheet is expanding outwards as it travels towards the subject because the photons in that sheet of light are all diverging.

So, let’s look at something tangible as an analogy – metric paper sizes!

How many sheets of A3 paper fit on a sheet of A2 paper?

That’s right, TWO – we’ve effectively doubled the surface area of the paper.

Now exposure works in stops – and making a 1 stop change in exposure effectively doubles or halves the exposure value depending on which way we’ve made the adjustment.

So moving from A3 to A2 is like making a 1 stop change in exposure; we’ve doubled the surface area of the paper.  BUT – we’ve not doubled the papers physical dimensions.

What paper size is twice the width AND twice the height of A3 – yep, that’s right, A1.

And how many sheets of A3 fit on a sheet of A1 – right again, 4.

So we have quadrupled the papers surface area – in exposure terms that would equate to 2 stops.

Now imagine a projector throwing an image onto a big screen and the screen to projector distance is 4 metres.  We go to the screen and measure the size of the projected image and it’s 1.5 metres by 2 metres.

How big will the image be if we move the projector to 8 metres from the screen?

Answer – 3 metres x 4 metres. (and the brightness of the image will have gone down by 2 stops).

And if we move the projector to 2 metres from the screen the image will be 0.75 metres x 1 metre. (and the brightness of the image will have increased by 2 stops!).

Inverse Square Law, Lights & Distances

Let’s say we have a theoretical flash with a metres guide number of 80.

If the subject is 10 metres from the light we need an aperture of f8 because 80/10 = 8.

If we now move the light to 5 metres from the subject our aperture decrease to 80/5 = f16

Halving the light-to-subject distance means we increase the overall intensity of the light (its effective flash output power) by 2 stops, so we have to reduce our overall exposure by two stops to compensate; otherwise we’ll just end up with 2 stops of over exposure.

And of course if we move the light away to 20 metres from the subject the inverse applies and we effectively reduce the flash output power by two stops and we’ll have to open the aperture up by two stops to avoid under exposure.

But what do we have to do in order to use f16 at 10 metres AND get correct exposure?

Use a flash with a guide number of 160 is what we’d need to do – it really is that simple.

Reality

So, how many guide number 45 speed lights would we need to equal one guide number 90 studio flash head in terms of effective flash output power?

Well it isn’t two – oh that we should be so lucky!

If we have two speed lights mounted together their cumulative guide number is equal to the square root of the sum of the squares of their individual guide numbers!

Sounds scary, but the answer is 63 or thereabouts.

But here’s the thing about photo-maths – it usually ends up as something really simple and this is no exception.

If you want to double the guide number you always need 4 identical units.

Do not forget what I’ve said above about published guide numbers – you have to ensure that the values were obtained using equal criteria, and manufacturers sometimes don’t always like to furnish you with the information you need in order to do easy comparisons.

Have they got something to hide – you may think that, but I couldn’t possibly comment!

What really does piss me off the meaningless crap they do furnish you with – watt-second, w/s, watt/sec or if you like Joules values.

The only thing these values do is inform you of the “potential energy” available at the capacitor; it’s no measure of how efficiently the flash tube converts that power into photons – and the photons is ALL we’re really interested in.

Other things such as tube temperature can have dramatic effects on both light output and the colour of that light.

Conclusion

This post has been a bit of a ramble but I’ve tried as best I can to give you a rough guide on how to compare one flash source with another.

Different photographers require different things – if all you want to do is shoot portraits and still life then shutter speeds above 1/250th synch are of little importance in general terms, so access to HSS/AutoFP via speed lights isn’t needed, and normal studio lights would be a far more economical proposition.

But on the other hand 8 speed lights in one bank, and two more banks of 4 speed lights each – all HSS/AutoFP compliant – crikey, the photographic possibilities are endless, and readily achievable – if your bank balance is endless too!

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