Metering Modes Explained

Camera Metering Modes

I always get asked about which camera metering mode I use,  and to be honest, I think sometimes the folk doing the asking just can’t get their heads around my simplistic, and sometimes quite brutal answers!

“Andy, it’s got to be more complicated than that surely….otherwise why does the camera give me so many options…?”

Well, I always like to keep things really simple, mainly because I’m not the brightest diamond in the jewellery shop, and because I’m getting old and most often times my memory keeps buggering off on holiday without telling me!

But before I espouse on “metering the Uncle Andy way” let’s take a quick look at exactly how the usual metering options work and their effects on exposure.

 

The Metering Modes

  • Average (a setting usually buried in the center-weighted menu)
  • Spot
  • Center-weighted
  • 3D Matrix (Nikon) or Evaluative (Canon)
Screen Shot 2014 02 26 at 13.34.22 Metering Modes Explained

Metering Mode Icons

You need to remember that metering is done via a separate sensor – not the IMAGE PLANE SENSOR (the contraption that records your images).  This separate RGB sensor is usually of a CCD design and resides in the top of the camera viewfinder housing.

In the Canon 1DX this sensor has a pixel count of 100,000, and in the current crop of Nikon FX bodies it’s 91,000.

Average Metering Mode

When set in this metering mode all that basically happens is that your exposure value for the shot is determined by the average tonal brightness value of the entire scene that is projected onto the metering sensor.

It’s a tad old fashioned to say the least, but it’s marginally better than having no metering at all!

 

Spot Metering Mode (click images to open at full size in a new window)

This metering mode, together Nikon Matrix and Canon Evaluative, relies on a combined use of the of AF sensor points and the dedicated RGB CCD metering sensor.

In the first and third images below pay particular attention to the “contents” of the AF/metering bracket.

Within our AF/meter bracket in image 1 sits a galvanized metal post and two windows, both of which have white frames and one is full of sky reflection.

spot3 600x324 Metering Modes Explained

Spot meter using the center AF/meter mark – 1/500th @ f9

In the next image we’ve moved that center AF/meter bracket over to an area of the sky using the normal Dpad control on the back of the camera.

Now the exposure value has jumped by 3 stops from 1/500th sec to 1/4000th sec.

spot1 600x324 Metering Modes Explained

Spot meter from the sky – 1/400th sec @ f9

On image 1 we thought the highlights were possibly “blown out” in the sky – but seeing as we now know the sky is only an average 3 stops brighter than the street scenery, and we know our camera has a dynamic range of perhaps 9 stops or more, we perhaps have to question that initial assumption.

In image 3 below we’ve moved the AF/meter bracket over to the left to span a lighter and a darker wall, and a black downspout – no white window frames or reflections of the sky in window glass.

This has now given us and exposure of 1/400th sec…

spot2 600x323 Metering Modes Explained

Spot meter from a more even mid tone in the scene – 1/400th @ f9

…and we still have to ask ourselves if we have actually blown the sky.

Let’s just ping this shot over to Lightroom and see shall we..

Lightroom a 600x298 Metering Modes Explained

Lightroom Histogram indicates highlight clipping in all three colour channels

But let’s just reduce the overall exposure and see if that detail is ACTUALLY on the sensor…

Lightroom b 600x312 Metering Modes Explained

Reducing the EXPOSURE in Lightroom shows us that ALL the sky/highlight detail has been recorded perfectly by the camera sensor

And can we make a good image inside Lightroom from this same RAW file that’s seemingly over exposed in the sky?

You bet ya we can:

Lightroom finished 600x363 Metering Modes Explained

The same RAW file with some simple processing in Lightroom

And with another 2 minutes work I could make it look even better; but even as it is just check that histogram and the way I’ve redistributed the tones – luvly-jubbly midtones!

Buy my Training Videos, or book a training day with me if you want to KNOW how to do this – don’t expect me to give EVERYTHING away for free on my blog – I have to eat you know!

Anyway, we digress, so back to metering!

Spot metering DOES have a place in my armory of tactics – it really comes into it’s own in HIGH CONTRAST situations such as the one illustrated; but one does have to take GREAT CARE in where you take that spot meter reading from.

Having said that, I don’t deploy it quite so much anymore because of the simplicity of exposure bracketing and HDR/32 bit float imaging.

 

Center-Weighted Metering Mode

Center weighted metering is something I NEVER use; basically it’s a refinement of basic average.

Historically it was the second metering mode to appear on cameras “back in the day” and at that time it was brilliant – but things have moved on a bit since then, and in my opinion it has no place any more.

Why?

Because of how it works.

A circular area centered in the frame is metered – the exposure value given is the AVERAGE of what is covered by said circle.

On Nikon FX bodies for example this center circle can be 8mm,12mm,15mm & 20mm in diameter based on a sensor size of 36mm x 24mm

The simple FULL FRAME AVERAGE metering mode exposure value is also taken.

The two values are now averaged out with a bias of 75% to the center circle and 25% to the full frame average.

AND the center area is FIXED; it cannot be moved around the frame like spot or matrix/evaluative.

20mmCWb 600x400 Metering Modes Explained

20mm center weighted metering on a well composed shot.

15mmCWb 600x400 Metering Modes Explained

15mm center weighted metering on a well composed shot.

12mmCWb 600x400 Metering Modes Explained

12mm center weighted metering on a well composed shot.

8mmCWb 600x400 Metering Modes Explained

8mm center weighted metering on a well composed shot.

So all-in-all, the center weighted metering mode is archaic and about as much use as a hole in the head.

Spot would make an awful lot more sense…….if it wasn’t for the fact that the shot was done with my go-to metering mode – MATRIX (or Evaluative if I was a Canon shooter).

 

The Matrix or Evaluative Metering Mode

D4R3164 Edit 600x400 Metering Modes Explained

Nikon Matrix metering mode – no fancy processing, basically straight RAW off the sensor.

A common problem that people have when ‘doing photography’ is that they LOOK, but they do not SEE…

Think back to what I said about SPOT metering – you really DO have to concentrate hard and actually SEE what objects in the scene are under that single spot.  This is hard to do especially with a wide angle lens as scene details are so small in the viewfinder.

They beauty of the spot metering mode is that it is:

  • very precise
  • moveable around the frame (given the area confines of the RGB metering sensor/AF array).

The one single redeeming feature of the Center-Weighted metering mode lies in the fact that it is variable in size.

Now imagine you had a metering mode that was centered on you key AF sensor, took on board the exposure values indicated, for example by the other 8 surrounding sensors if you are using a 9 point group as your auto focus mode; AND followed that AF sensor group around the frame as you basically compose the shot.

On top of that, what if the meter could also use lens data, and complex mixing algorithms based on scene recognition instead of the daft 75:25 mixing ratio of the center weighted metering mode?

Sounds good, and it’s called 3d Matrix metering by Nikon, and Evaluative by Canon.

Canon and Nikon use their own individual methods of obtaining this complex set of metering calculations, but at the end of the day they amount to one and the same thing – a really simple and effortless way for the camera operator to obtain a very good exposure.

Your Uncle Andy’s approach to metering is really simple – all my cameras are set to Matrix metering and they hardly ever move.

Like spot metering, the exposure value is calculated  based on a point SPECIFIED by you, the operator.

But unlike spot metering, which is basically a ‘dumb’ reading, the matrix metering mode takes the opinion that what you are focused on is actually the bit of the frame that’s important – so that’s place it starts its exposure evaluation from.

Now matrix is not infallible, far from it – just try it in high contrast situations and you’ll soon see.

But with a little experience you begin to recognize scenarios and what they mean in terms of exposure value; this experience then leads you to take command of the exposure compensation adjustments on your camera.

Take these 3 images:

D3C2791 2 600x400 Metering Modes Explained

Matrix -1.0Ev 1/2500th @ f6.3

With this Kestrel we have bright sunny conditions – one of those potential high contrast scenarios I mentioned that can catch Matrix out if you are not careful.

Matrix exposure would have indicated 1/1200th sec shutter speed.

Under exposing by -1.0Ev on the compensation dial gives me 1 stop faster shutter speed AND protects those shiny highlights on the birds beak and very pale feathers on the face and wing edges.

D3C8864 Edit 6 266x400 Metering Modes Explained

Matrix without compensation or +/-0.0Ev 1/1000th @ f8

I know it doesn’t look like it, but this upended swan close up is basically white on white, or low contrast situation – so I let the camera go with the Matrix exposure of 1/1000th and no compensation.

WIP00054733 Edit 2 3 266x400 Metering Modes Explained

Matrix + 1.3Ev 1/400th @ f6.3

Another white on white situation then – OH NO IT ISN’T.

The swan was fine detail white-on-white an NOTHING else – the camera assumes that this commonest tone, white, is actually mid grey, and so exposes the whites as mid tones.  The warm highlight under the wing is therefore protected from blowing due to the massive amount of headroom the highlights have on a linear capture.

If you are unsure of what I mean take a look at the top greyscale

LinVsHum31 600x181 Metering Modes Explained

Linear (top) vs Encoded Gamma

You may also want to check back on the post about Gamma

So, to get back to “Miss Arctic Circle” above – I said that she is NOT a “white-on-white” or low contrast situation.

She’s got the hazel brown eyes, detail in that near black nose, and if she smiles a pinkish tongue and less than white teeth.

Matrix would have been indicating a shutter speed of either 1/1000th or 1/1200th, and at that level of exposure value the whites would have been exposed more as mid tones – and so those darker areas of the eyes, nose etc would have been considerably under exposed and either lost all their detail, or the detail would have to be exposure-boosted in post processing, which would have made those areas noisy.

Those darker areas represent a very small percentage of the total image field, perhaps about 4% at most, so spot metering them would have been fairly impossible with any degree of accuracy.

But going with Matrix and +1.3Ev dialed in on the exposure compensation control in effect, pushes the common tones up the linear gamma curve and exposes them as upper mid tones and low highlights – which is indeed what they are – and exposes the darker areas further up the gamma curve as lower mid tones – again, which is what they are.

With experience, riding the exposure compensation dial in conjunction with the matrix or evaluative metering modes becomes second-nature; your eye becomes accustomed to seeing the necessary corrections as you are shooting and moving around, and your fingers get accustomed to making the adjustments without the need to take your eye from the viewfinder.

So that’s how I look at the subject of metering modes – matrix and Ev compensation – Keeping It Simple.

 

Please consider supporting this blog.

This blog really does need your support. All the information I put on these pages I do freely, but it does involve costs in both time and money.

If you find this post useful and informative please could you help by making a small donation – it would really help me out a lot – whatever you can afford would be gratefully received.

Your donation will help offset the costs of running this blog and so help me to bring you lots more useful and informative content.

Many thanks in advance.

 

Nikon D4S

The new Nikon D4S announced today

 

D4S D4 Nikon D4S

Nikon D4S left & D4 right

Well, that’s about right, my sexy Nikon D4 is officially out of date, and thanks to the Nikon D4S I’ve just lost a grand off the resale value of my camera – cheers chaps…..

Is Uncle Andy stressed at all about being kitted out with yesterdays gear?

Nope, not really.

So what’s new on the Nikon D4S ?

  • Well there’s been a few ergonomic tweaks which basically mean nothing for starters.
  • Seemingly dispelled are the rumours that it would have a higher Mp count – apparently this stays the same at 16.2Mp.
  • I was expecting some major change in AF but no, they’ve kept the venerable Multi-Cam 3500FX system.
  • New sensor design.
  • BUT – they’ve changed the image processor to Expeed 4 from Expeed 3.
  • AND – they’ve changed the battery from EN-EL18 to an EN-EL18a.

Bare in mind all I’m going on is the web – perish the thought that Nikon would ever think my opinion worthy of note and ACTUALLY SEND ME ONE.

Other changes:

  • A new Group Area AF mode – which from my own photography PoV is fairly meaningless, seeing as we already have 9 point dynamic AF – I can’t see it’ll make much difference. Plus, the Group AF mode always focusses on the nearest point – something you rarely want the camera to do!
  • 6 possible white balance presets as opposed to 3 on the D4 – I jam all my cameras into Cloudy B1 custom WB and leave them there – so this improvement isn’t worth jumping up and down about either.
  • Fairly gimmicky S Raw
  • Spot White Balance

On the storage front most reports say that the D4S carries over the D4 crazy arrangement of 1x CF plus 1x XQD.

My Basic Thoughts:

New Sensor – well the benefits can’t been seen by yours truly until I see a few RAW files from it – preferably taken by myself.

I’m glad they’ve kept it to 16.2Mp – if you crunch the numbers this is the optimum Mp count for an FX sensor – as Canon worked out aeons ago with the 1DsMk2; but then joined the stupid Mp race.

Image Processor changes – well, it’s reportedly 30% faster than the Expeed 3, which basically means that the D4S fires off images to storage 30% faster.

Now I can go out with the D4 and shoot getting on for 100 uncompressed 14bit RAW files in one continuous burst at 8 or 9 fps – do I want to chew through my storage any faster?  NO!

The Expeed 4 gives better high ISO performance?

Well perhaps it does, but I look at it this way.  If light is so damn low that you need to shoot at crackpot ISO numbers then you can say one thing – the light is crap.

If the light is crap then the image will look like crap – it’s just that with the Expeed 4 it’ll be slightly less noisy crap.

If I can pull 1/8000th sec at f7 or f8 at 3200ISO in half descent looking light using a D4 – which I do regularly – then why do I need a higher ISO capability?

The Red Squidger images you’ve seen in the previous blog articles are all 2000ISO and there is ZERO noise degradation – so again, why do I need more ISO capability.

Now if I was a ‘jobbing’ photo-jounalist, or I was embedded with the troops in Afghanistan or something of that ilk then I’d perhaps have a much different attitude.

But I’m not, and from my own perspective of wildlife & natural history photography these changes are of little interest to me – especially when they have a £5k price tag.

Battery Changes

There was always a persistent gripe about the battery life of the D4 EN-EL18 power cell – well, I’ve got two of them and have had no problems AT ALL with batteries running low.

I was REALLY annoyed that they switched from EN-EL4A D2/D3 style batteries – I’d got a handful of those already, and now when I go to Norway in June I’ve got to take 2 bloody chargers with me: yes the venerable D3 will be getting a summer holiday this year as second camera.

So, for me at least, the increased battery life of the new Nikon D4S 18a batteries is somewhat inconsequential – why do I want a battery that lasts longer than ‘for ever’ ??

Other Changes/Additions

I can’t see anything that excites me:  spot white balance?  Go and buy a Colour Checker Passport and do the job right – and that doesn’t cost £5k either (though they are a bit pricey).

Group Area AF – do me a favour (see above).

6 White Balance presets – what’s the point?

All of the above could be given away by Nikon as a firmware update for the D4 if they fancied being generous!

What I Would Have Got Excited About.

Twin UDMA 7 CF card slots and an XQD slot for dedicated video recording.

An improved AF module.

The ability to select ‘matched pairs’ of sensors – Canon offered this years ago and it was brilliant.

Internally recorded FX video of EXACTLY the same quality as that of a Canon 5D3, or at least the same quality as internal 1080p CROP.

AF mode selector back WHERE IT SHOULD BE!

Me being put in charge at Nikon!

In Conclusion

Do I want to buy one (even if I had the dough) – NO!

Do I wish I could afford one – NO!

Would I swap my D4 for a D4s – well of course I would.

Seriously though, I can just see an awful lot of people getting “hot under the collar” and stressing over this latest incarnation of this pro body from Nikon; but seriously, if you are then you need to just take a quiet step back and think about things calmly.

There is nothing – IMHO of course – on the D4S that warrants upgrading from the D4 – unless you have a penchant for spending your money that is.

But if you are still on a D3 or something older, and were thinking about buying a D4 – then hold off a while until the D4S in available; it’s makes better fiscal sense.

 

Please consider supporting this blog.

This blog really does need your support. All the information I put on these pages I do freely, but it does involve costs in both time and money.

If you find this post useful and informative please could you help by making a small donation – it would really help me out a lot – whatever you can afford would be gratefully received.

Your donation will help offset the costs of running this blog and so help me to bring you lots more useful and informative content.

Many thanks in advance.

 

Auto Focus & Shooting Speed

Auto Focus & Shooting Speed

 

Firstly, an apology to my blog followers for the weird blog post notification this morning – I had one of those “senior moments” where I confused the Preview button with Publish – DOH!

There is truly no hope………..!  But let’s get on….

The effectiveness of auto focus and its ability to track and follow a moving subject IS INFLUENCED by frame rate.

Why is this I here you ask.

Well, it’s simple, and logical if you think about it – where are your AF sensors?

They’re in the bottom of your cameras mirror box.

Most folk thing that the mirror just sits there, reflecting at 45 degrees all the light that comes through the lens up to the focus screen and viewfinder.  The fact that the mirror is still DOWN when they are using the auto focus leads most people into thinking the AF sensor array is elsewhere – that’s if they can be bothered to think about it in the first place.

 

So how does the AF array SEE the scene?

Because the center area of the main mirror is only SEMI silvered, and in reality light from the lens does actually pass through it.

 

D4R4484a 600x400 Auto Focus & Shooting Speed

Main mirror of a Nikon D2Xs in the down position.

 

Now I don’t recommend you jam a ball point pen under your own main mirror, but in the next image:

 

D4R4484b1 600x400 Auto Focus & Shooting Speed

Main mirror of a Nikon D2Xs lifted so you can see the secondary mirror.

 

Now there’s a really good diagram of the mechanics at http://www.reikan.co.uk/ – makers of FoCal software, and I’ll perhaps get my goolies cut of for linking to it, but here it is:

 

af04 Auto Focus & Shooting Speed

This image belongs to Reikan

 

As you can now hopefully understand, light passes through the mirror and is reflected downwards by the secondary mirror into the AF sensor array.

As long as the mirror is DOWN the auto focus sensor array can see – and so do its job.

Unless the MAIN mirror is fully down, the secondary mirror is not in the correct position to send light to the auto focus sensor array – SO GUESS WHAT – that’s right, your AF ain’t working; or at least it’s just guessing.

So how do we go about giving the main mirror more “down time”?  Simply by slowing the frame rate down is how!

When I’m shooting wildlife using a continuous auto focus mode then I tend to shot at  5 frames per second in Continuous LOW (Nikon-speak) and have the Continuous HIGH setting in reserve set for 9 frames per second.

 

The Scenario Forces Auto Focus Settings Choices

From a photography perspective we are mainly concerned with subjects CROSSING or subjects CLOSING our camera position.

Once focus is acquired on a CROSSING subject (one that’s not changing its distance from the camera) then I might elect to use a faster frame rate as mirror-down-time isn’t so critical.

But subjects that are either CLOSING or CROSSING & CLOSING are far more common; and head on CLOSING subjects are the ones that give our auto focus systems the hardest workout – and show the system failures and short-comings the most.

Consider the focus scale on any lens you happen to have handy – as you focus closer to you the scale divisions get further apart; in other words the lens focus unit has to move further to change from say 10 meters to 5 meters than it does to move from 15 meters to 10 meters – it’s a non-linear scale of change.

So the closer a subject comes to your camera position the greater is the need for the auto focus sensors to see the subject AND react to its changed position – and yes, by the time it’s acquired focus and is ready to take the next frame the subject is now even closer – and things get very messy!

That’s why high grade dSLR auto focus systems have ‘predictive algorithms’ built into them.

Also. the amount of light on the scene AND the contrast between subject and background ALL effect the ability of the auto focus to do its job.  Even though most pro-summer and all pro body systems use phase detection auto focus, contrast between the subject to be tracked and its background does impact the efficiency of the overall system.

A swan against a dark background is a lot easier on the auto focus system than a panther in the jungle or a white-tailed eagle against a towering granite cliff in Norway, but the AF system in most cameras is perfectly capable of acquiring, locking on and tracking any of the above subjects.

So as a basic rule of thumb the more CLOSING a subject is then the LOWER your frame rate needs to be if you are looking for a sharp sequence of shots.  Conversely the more CROSSING a subject is then the higher the frame rate can be and you might still get away with it.

 

Points to Clarify

The mechanical actions of an exposure are:

  1. Mirror lifts
  2. Front shutter curtain falls
  3. Rear shutter curtain falls
  4. Mirror falls closed (down)

Here’s the thing; the individual time taken for each of these actions is the same ALL the time – irrespective of whether the shutter speed is 1/8000th sec or 8 sec; it’s the gap in between 2. & 3. that makes the difference.

And it’s the ONLY thing shutter-related we’ve got any control over.

So one full exposure takes t1 + t2 + shutter speed + t3 +t4, and the gap between t4 and the repeat of t1 on the next frame is what gives us our mirror down time between shots for any given frame rate.  So it’s this time gap between t4 and the repeat of t1 that we lengthen by dropping the shooting speed frame rate.

There’s another problem with using 10 or 11 frames per second with Nikon D3/D4 bodies.

10 fps on a D3 LOCKS the exposure to the values/settings of the first frame in the burst.

11 fps on a D3 LOCKS both exposure AND auto focus to the values/settings of the first frame in the burst.

11 fps on a D4 LOCKS both exposure AND auto focus* to those of the first frame in the burst – and it’s one heck of a burst to shoot where all the shots can be out of focus (and badly exposed) except the first one!

*Page 112 of the D4 manual says that at 11fps the second and subsequent shots in a burst may not be in focus or exposed correctly.

That’s Nikon-speak for “If you are photographing a statue or a parked car ALL your shots will be sharp and exposed the same; but don’t try shooting anything that’s getting closer to the camera, and don’t try shooting things where the frame exposure value changes”.

 

There’s a really cool video of 11 fps slowed right down with 5000fps slo-mo  HERE  but for Christ’ sake turn your volume down because the ST is some Marlene Dietrich wannabe!

 

So if you want to shoot action sequences that are sharp from the first frame to the last then remember – DON’T be greedy – SLOW DOWN!

 

Please consider supporting this blog.

This blog really does need your support. All the information I put on these pages I do freely, but it does involve costs in both time and money.

If you find this post useful and informative please could you help by making a small donation – it would really help me out a lot – whatever you can afford would be gratefully received.

Your donation will help offset the costs of running this blog and so help me to bring you lots more useful and informative content.

Many thanks in advance.

 

Flash Photography

Flash Photography

 

D4R4090 266x400 Flash Photography

Really Cute Red Squirrel

 

On Sunday myself and my buddy Mark Davies made a short foray up to the Lake District and our small Red Squirrel site.  The weather was horrible, sleet, sun. rain, cloudy, sunny then rain again – in other words just not conducive to a half-descent session on the D4.

The one Achilles Heal with this site is the fact that it’s hard to get a descent background for your shots – it’s in the middle of a small wooded valley and you just can’t get away from tree trunks in the background.

This is further complicated by the fact that the “Squidgers” have a propensity for keeping in the ‘not so sunny’ bits, so frequently you end up with a scenario where backgrounds are brighter than foregrounds – which just won’t DO!

So what’s needed is some way to switch the lighting balance around to give a brighter foreground/subject AND a darker background.

Now that sounds all very well BUT; how do we achieve it?

Reflectors perhaps?  They’d do the trick but have one big problem; they rely on AMBIENT light  – and in the conditions we were shooting in the other day the value of the ambient light was up and down like a Yo-Yo.

Wouldn’t it be cool if we could have a consistent level of subject/foreground illumination AND at the same time have some degree of control over the exposure of the background?

Well with flash we can do just that!

Let’s look at a shot without flash:

 

D4R4109 600x400 Flash Photography

No FLASH, AMBIENT light only – 1/320th @ f7.1

 

I don’t suppose this shot is too bad because the background isn’t strongly lit by the sun (it’s gone behind a cloud again!) but the foreground and background are pretty much the same exposure-wise.  For me there is not enough tonal separation between the two areas of the image, and the lighting is a bit flat.

If we could knock a stop or so out of the background; under expose it, then the image would have more tonal separation between foreground and background, and would look a lot better, but of course if we’re just working with ambient light then our adjusted exposure would under expose the foreground as well, so we’d be no better off.

Now look at the next image – we’ve got a background that’s under exposed by around  -1.5Ev, but the subject and foreground are lit pretty much to the same degree as before, and we’ve got a little more shape and form to the squirrel itself – it’s not quite so flat-looking.

 

D4R4230 600x400 Flash Photography

With FLASH added – 1/800th @ f7.1

 

The image also has the slight sense that it’s been shot in more sunny conditions – which I can promise you it wasn’t !

And both images are basically straight off the camera, just with my neutral camera profile applied to them on import.

 

The Set Up

setup 400x400 Flash Photography

The Setup – shocking iPhone 3 quality!

 

The first secret to good looking flash photography OF ANY KIND is to get the damn flash OFF the camera.

If we were in a totally dark studio with the sexiest looking model on the planet we’d NOT be lighting her with one light from the camera position now would we?

So we use basic studio lighting layouts where ever we can.

There are two other things to consider too:

  •   It’s broad daylight, so our exposure will contain both FLASH and an element of AMBIENT light – so we are working along the premise of ADDING to what’s already there.
  •   If we put the flash closer to the subject (off camera) then the output energy has less distance to travel in order to do its job – so it doesn’t have to have as much power behind it as it would have if emanating from the camera position.

 

You can see in the horrible iPhone 3 shot I took of the setup that I’m using two flash guns with white Lambency diffusers on them; one on a stand to the left and slightly in front of the log where the squirrels will sit, and one placed on the set base (Mr. Davies old knackered Black & Decker Workmate!) slightly behind the log and about the same distance away from where I anticipate a squirrel will sit on the log as the left flash.

The thing to note here is that I’m using the SIDE output of these Lambency diffuser domes and NOT the front – that’s why they are pointed up at the sky. The side output of these diffusers is very soft – just what the flash photography doctor ordered in terms of ‘keeping it real’.

The left light is going to be my MAIN light, the right is my FILL light.

The sun, when & if it decides to pop its head out, will be behind me and to my left so I place my MAIN light in a position where it will ‘simulate’ said ball in the sky.

The FILL light basically exists to ‘counter balance’ the ‘directionality’ of the MAIN light, and to weaken any shadows thrown by the MAIN light.

Does this flash bother a subject? For the most part NOT SO YOU’D NOTICE!

Take a look at the shot below – the caption will be relevant shortly.

D4R4225 600x400 Flash Photography

This SB800 has just fired in “front curtain synch” and the balance of the exposure is from the ambient light. Does the squirrel look bothered?

Settings & The Black Art!

Before we talk about anything else I need to address the shutter curtain synch question.

We have two curtain synch options, FRONT & REAR.

Front Curtain (as in the shot above) – this means that the flash will fire as the front curtain starts to move, and most likely, the flash will be finished long before the rear curtain closes. If your subject reacts to the flash then some element of subject movement might be present in the shot due to the ambient light part of the exposure.

Rear Curtain Synch – my recommended ‘modus operandi’ – the ‘ambient only’ part of the exposure gets done first, then the flash fires as the rear curtain begins to close the exposure. This way, if the subject reacts to the flash the exposure will be over before it has chance to – MOSTLY!

The framing I want, and the depth of field I want dictates my camera position and aperture – in this case f7 or f8 – actually f7.1 is what I went for.

 

I elect to go with 2000 iso on the D4.

So now my only variable is shutter speed.

Ambient light dictates that to be 1/320th on average, and I want to UNDER EXPOSE that background by at least a stop and a bit (technical terms indeed!) so I elect to use a shutter speed of 1/800th.

So that’s it – I’m done; seeing as the light from the flashes will be constant my foreground/subject will ALWAYS be exposed correctly. In rear curtain synch I’ll negate the risk of subject movement ‘ghosting’ in the image, and at 1/800th I’ll have a far better chance of eliminating motion blur caused by a squirrel chewing food or twitching its whiskers etc.

 

Triggering Off-Camera Flashes

 

We can fire off-camera flashes in a number of ways, but distance, wet ground, occasional rain and squirrels with a propensity for chewing everything they see means CORDS ain’t one of ’em!

With the Nikon system that I obviously use we could employ another flash on-camera in MASTER/COMMANDER mode, with the flash pulse deactivated; or a dedicated commander such as the SU800; or if your camera has one, the built-in flash if it has a commander mode in the menu.

The one problem with Nikon CLS triggering system, and Canons as far as I know, is the reliance upon infra-red as the communication band. This is prone to a degree of unreliability in what we might term ‘dodgy’ conditions outdoors.

I use a Pocket Wizard MiniTT1 atop the camera and a FlexTT5 under my main light. The beauty of this system is that the comms is RADIO – far more reliable outdoors than IR.

Because a. I’m poor and can’t afford another TT5, and b. the proximity of my MAIN and FILL light, I put the SB800 FILL light in SU mode so it gets triggered by the flash from the MAIN light.

What I wouldn’t give for a dozen Nikon SB901’s and 12 TT5s – I’d kill for them!

The MAIN light itself is in TTL FP mode.

The beauty of this setup is that the MAIN light ‘thinks’ the TT5 is a camera, and the camera ‘thinks’ the miniTTL is a flash gun, so I have direct communication between camera and flash of iso and aperture information.

Also, I can turn the flash output down by up to -3Ev using the flash exposure compensation button without it having an effect on the background ambient exposure.

Don’t forget, seeing as my exposure is always going to 1/800th @ f7.1 at 2000 iso the CAMERA is in MANUAL exposure mode. So as long as the two flashes output enough light to expose the subject correctly at those settings (which they always will until the batteries die!) I basically can’t go wrong.

When shooting like this I also have a major leaning towards shooting in single servo – one shot at a time with just one AF point active.

 

Flash Photography – Flash Duration or Burn Time

Now here’s what you need to get your head around. As you vary the output of a flash like the SB800 the DURATION of the flash or BURN TIME of the tube changes

Below are the quoted figures for the Nikon SB800, burn time/output:

1/1050 sec. at M1/1 (full) output
1/1100 sec. at M1/2 output
1/2700 sec. at M1/4 output
1/5900 sec. at M1/8 output
1/10900 sec. at M1/16 output
1/17800 sec. at M1/32 output
1/32300 sec. at M1/64 output
1/41600 sec. at M1/128 output

On top of that there’s something else we need to take into account – and this goes for Canon shooters too; though Canon terminology is different.

Shutter Speed & The FP Option

35mm format cameras all have a falling curtain shutter with two curtains, a front one, and a rear one.

As your press the shutter button the FRONT curtain starts to fall, then the rear curtain starts to chase after it, the two meet at the bottom of the shutter plane and the exposure is over.

The LONGER or slower the shutter speed the greater head-start the front curtain has!

At speeds of 1/250th and slower the front curtain has reached the end of its travel BEFORE the rear curtain wakes up and decides to move – in other words THE SENSOR is FULLY exposed.

The fastest shutter speed that results in a FULLY EXPOSED film plane/sensor is the basic camera-to-flash synch speed; X synch as it used to be called, and when I started learning about photography this was usually 1/60th; and on some really crap cameras it was 1/30th!

But with modern technology and light weight materials these curtains can now get moving a lot faster, so basic synch now runs at 1/250th for a full frame DSLR.

If you go into your flash camera menu you’ll find an AUTO FP setting for Nikon, Canon refer to this as HSS or High Speed Synch – which makes far more sense (Nikon please take note, Canon got something right so please replicate!).

There’s something of an argument as to whether FP stands for Focal Plane or Flash Pulse; and frankly both are applicable, but it means the same as Canon’s HSS or High Speed Synch.

At speeds above/faster than 1/250th the sensor/film plane is NOT fully exposed. The gap between the front and rear curtains forms a slot or ‘letter box’ that travels downwards across the face of the sensor, so the image is, if you like, ‘scanned’ onto the imaging plane.

Obviously this is going to cause on heck of an exposure problem if the flash output is ‘dumped’ as a single pulse.

So FP/HSS mode physically pulses or strobes the flash output to the point where it behaves like a continuous light source.

If the flash was to fire with a single pulse then the ‘letterbox slot’ would receive the flash exposure, but you’d end up with bands of under exposure at the bottom or top of the image depending on the curtain synch mode – front or rear.

In FP/HSS mode the power output of each individual pulse in the sequence will drop as the shutter speed shortens, so even though you might have 1:1 power selected on the back of the flash itself (which I usually do on the MAIN light, and 1/2 on the FILL light) the pulses of light will be of lower power, but their cumulative effect gives the desired result.

By reviewing the shot on the back of the camera we can compensate for changes in ambient in the entire scene (we might want to dilute the effect of the main light somewhat if the sun suddenly breaks out on the subject as well as the background) by raising the shutter speed a little – or we might want to lighten the shot globally by lowering the shutter speed if it suddenly goes very gloomy.

We might want to change the balance between ambient and flash; this again can be done from the camera with the flash exposure compensation controls; or if needs be, by physically getting up and moving the flash units are little nearer or further away from the subject.

All in all, using flash is really easy, and always has been.

Except nowadays manufacturers tend to put far more controls and modes on things then are really necessary; the upshot of which is to frighten the uninitiated and then confuse them even further with instruction manuals that appear to be written by someone under the influence of Class A drugs!

 

D4R4091 266x400 Flash Photography

“Trouble Brewing..” Confrontation over the right to feed between two Red Squirrels.

 

The whole idea of flash is that it should do its job but leave no obvious trace to the viewer.

But its benefits to you as the photographer are invaluable – higher shutter speeds, more depth of field and better isolation of the subject from its background are the three main ones that you need to be taking advantage of right now.

 

If you have the gear and don’t understand how to use it then why not book a tuition day with me – then perhaps I could afford some more TT5s!

Please consider supporting this blog.

This blog really does need your support. All the information I put on these pages I do freely, but it does involve costs in both time and money.

If you find this post useful and informative please could you help by making a small donation – it would really help me out a lot – whatever you can afford would be gratefully received.

Your donation will help offset the costs of running this blog and so help me to bring you lots more useful and informative content.

Many thanks in advance.

 

Paper White – Desktop Printing 101

Paper White video

A while back I posted an article called How White is Paper White

As a follow-up to my last post on the basic properties of printing paper media I thought I’d post this video to refresh the idea of “white”.

In this video we basically look at a range of 10 Permajet papers and simply compare their tints and brightness – it’s an illustration I give at my print workshops which never fails to amaze all the attendees.

I know I keep ‘banging on’ about this but you must understand:

  • Very few paper whites are even close to being neutral.
  • No paper is WHITE in terms of luminosity – RGB 255 in 8 bit colour terms.
  • No paper can hold a true black – RGB 0 in 8 bit colour terms.

In real-world terms ALL printing paper is a TINTED GREY – some cool, some warm.

D4R8269 Edit 21 1024x674 Paper White   Desktop Printing 101

If we attempted to print the image above on a cool tinted paper then we would REDUCE or even CANCEL OUT the warm tonal effects and general ‘atmosphere’ of the image.

Conversely, print it to a warmer tinted ‘paper white’ and the atmosphere would be enhanced.

Would this enhancement be a good thing?  Well, er NO – not if we were happy with our original ‘on screen’ processing.

You need to look upon ‘paper white’ as another TOOL to help you achieve your goal of great looking photographs, with a minimum of fuss and effort on your part.

We have to ‘soft proof’ our images if we want to get a print off the printer that matches what we see on our monitor.

But we can’t soft proof until we have made a decision about what paper we are going to soft-proof to.

Choosing a paper who’s characteristics match our finished ‘on screen’ image in terms of TINT especially, will make the job of soft proofing much easier.

How, why?

Proper soft proofing requires us to make a copy of our original image (there’s most peoples first mistake – not making a copy) and then making adjustments to said copy, in a soft proof environment, so that it it renders correctly on the print – in other words it matches our original processed image.

Printing from Photoshop requires a hard copy, printing from Lightroom is different – it relies on VIRTUAL copies.

Either way, this copy and its proof adjustments are what get sent to the printer along what we call the PRINT PIPELINE.

The print pipeline has to do a lot of work:

  • It has to transpose our adjusted/soft proofed image colour values from additive RGB to print CMYK
  • It has to up sample or interpolate the image dpi instructions to the print head, depending on print output size.
  • It has to apply the correct droplet size instructions to each nozzle in the print head hundreds of times per second.
  • And it has to do a lot of other ‘stuff’ besides!!

The key component is the Printer Driver – and printer drivers are basically CRAP at carrying out all but the simplest of instructions.

In other words they don’t like hard work.

Printing to a paper white that matches our image:

  • Warm image to warm tint paper white
  • Cool image to cool paper white

will reduce to the amount of adjustments we have to make under soft proofing and therefore REDUCE the printer driver workload.

The less work the print driver has to do, the lower is the risk of things  ‘getting lost in translation‘ and if nothing gets lost then the print matches the on screen image – assuming of course that your eyes haven’t let you down at the soft proofing stage!

cool 600x387 Paper White   Desktop Printing 101

IMPORTANT – Click Image to Enlarge in new window

If we try to print this squirrel on the left to Permajet Gloss 271 (warmish image to very cool tint paper white) we can see what will happen.

We have got to make a couple of tweaks in terms on luminosity BUT we’ve also got to make a global change to the overall colour temperature of the image – this will most likely present us with a need for further  opposing colour channel adjustments between light and dark tones.

 

Warm 600x387 Paper White   Desktop Printing 101

IMPORTANT – Click Image to Enlarge in new window

Whereas the same image sent to Permajet Fibre Base Gloss Warmtone all we’ll have to do is tweak the luminosity up a tiny bit and saturation down a couple of points and basically we’ll be sorted.

So less work, and less work means less room for error in our hardware drivers; this leads to more efficient printing and reduced print production costs.

And reduced cost leads to a happy photographer!

Printing images is EASY –  as long as you get all your ducks in a row – and you’ve only got a handful of ducks to control.

Understanding print media and grasping the implications of paper white is one of those ducks………

This video is an extract from a Lightroom printing tutorial title I’m working on for release later in the year.

Please consider supporting this blog.

This blog really does need your support. All the information I put on these pages I do freely, but it does involve costs in both time and money.

If you find this post useful and informative please could you help by making a small donation – it would really help me out a lot – whatever you can afford would be gratefully received.

Your donation will help offset the costs of running this blog and so help me to bring you lots more useful and informative content.

Many thanks in advance.

 

Desktop Printing 101

Understanding Desktop Printing – part 1

 

print1 Desktop Printing 101Desktop printing is what all photographers should be doing.

Holding a finished print of your epic image is the final part of the photographic process, and should be enjoyed by everyone who owns a camera and loves their photography.

But desktop printing has a “bad rap” amongst the general hobby photography community – a process full of cost, danger, confusion and disappointment.

Yet there is no need for it to be this way.

Desktop printing is not a black art full of ‘ju-ju men’ and bear-traps  – indeed it’s exactly the opposite.

But if you refuse to take on board a few simple basics then you’ll be swinging in the wind and burning money for ever.

Now I’ve already spoken at length on the importance of monitor calibration & monitor profiling on this blog HERE and HERE so we’ll take that as a given.

But in this post I want to look at the basic material we use for printing – paper media.

Print Media

A while back I wrote a piece entitled “How White is Paper White” – it might be worth you looking at this if you’ve not already done so.

Over the course of most of my blog posts you’ll have noticed a recurring undertone of contrast needs controlling.

Contrast is all about the relationship between blacks and whites in our images, and the tonal separation between them.

This is where we, as digital photographers, can begin to run into problems.

We work on our images via a calibrated monitor, normally calibrated to a gamma of 2.2 and a D65 white point.  Modern monitors can readily display true black and true white (Lab 0 to Lab 100/RGB 0 to 255 in 8 bit terms).

Our big problem lies in the fact that you can print NEITHER of these luminosity values in any of the printer channels – the paper just will not allow it.

A papers ability to reproduce white is obviously limited to the brightness and background colour tint of the paper itself – there is no such think as ‘white’ paper.

But a papers ability to render ‘black’ is the other vitally important consideration – and it comes as a major shock to a lot of photographers.

Let’s take 3 commonly used Permajet papers as examples:

  • Permajet Gloss 271
  • Permajet Oyster 271
  • Permajet Portrait White 285

The following measurements have been made with a ColorMunki Photo & Colour Picker software.

L* values are the luminosity values in the L*ab colour space where 0 = pure black (0RGB) and 100 = pure white (255RGB)

Gloss paper:

  • Black/Dmax = 4.4 L* or 14,16,15 in 8 bit RGB terms
  • White/Dmin = 94.4 L* or 235,241,241 (paper white)

From these measurements we can see that the deepest black we can reproduce has an average 8bit RGB value of 15 – not zero.

We can also see that “paper white” has a leaning towards cyan due to the higher 241 green & blue RGB values, and this carries over to the blacks which are 6 points deficient in red.

Oyster paper:

  • Black/Dmax = 4.7 L* or 15,17,16 in 8 bit RGB terms
  • White/Dmin = 94.9 L* or 237,242,241 (paper white)

We can see that the Oyster maximum black value is slightly lighter than the Gloss paper (L* values reflect are far better accuracy than 8 bit RGB values).

We can also see that the paper has a slightly brighter white value.

Portrait White Matte paper:

  • Black/Dmax = 25.8 L* or 59,62,61 in 8 bit RGB terms
  • White/Dmin = 97.1 L* or 247,247,244 (paper white)

You can see that paper white is brighter than either Gloss or Oyster.

The paper white is also deficient in blue, but the Dmax black is deficient in red.

It’s quite common to find this skewed cool/warm split between dark tones and light tones when printing, and sometimes it can be the other way around.

And if you don’t think there’s much of a difference between 247,247,244 & 247,247,247 you’d be wrong!

The image below (though exaggerated slightly due to jpeg compression) effectively shows the difference – 247 neutral being at the bottom.

x1 Desktop Printing 101

247,247,244 (top) and 247,247,247 (below) – slightly exaggerated by jpeg compression.

See how much ‘warmer’ the top of the square is?

But the real shocker is the black or Dmax value:

Matte sRGB 900x723 Desktop Printing 101

Portrait White matte finish paper plotted against wireframe sRGB on L*ab axes.

The wireframe above is the sRGB colour space plotted on the L*ab axes; the shaded volume is the profile for Portrait White.  The sRGB profile has a maximum black density of 0RGB and so reaches the bottom of vertical L axis.

However, that 25.8 L* value of the matte finish paper has a huge ‘gap’ underneath it.

The higher the black L* value the larger is the gap.

What does this gap mean for our desktop printing output?

It’s simple – any tones in our image that are DARKER, or have a lower L* value than the Dmax of the destination media will be crushed into “paper black” – so any shadow detail will be lost.

Equally the same can be said for gaps at the top of the L* axis where “paper white” or Dmin is lower than the L* value of the brightest tones in our image – they too will get homogenized into the all-encompassing paper white!

Imagine we’ve just processed an image that makes maximum use of our monitors display gamut in terms of luminosity – it looks magnificent, and will no doubt look equally as such for any form of electronic/digital distribution.

But if we send this image straight to a printer it’ll look really disappointing, if only for the reasons mentioned above – because basically the image will NOT fit on the paper in terms of contrast and tonal distribution, let alone colour fidelity.
It’s at this point where everyone gives up the idea of desktop printing:

  • It looks like crap
  • It’s a waste of time
  • I don’t know what’s happened.
  • I don’t understand what’s gone wrong

Well, in response to the latter, now you do!

But do we have to worry about all this tech stuff ?

No, we don’t have to WORRY about it – that’s what a colour managed work flow & soft proofing is for.

But it never hurts to UNDERSTAND things, otherwise you just end up in a “monkey see monkey do” situation.

And that’s as dangerous as it can get – change just one thing and you’re in trouble!

But if you can ‘get the point’ of this post then believe me you are well on your way to understanding desktop printing and the simple processes we need to go through to ensure accurate and realistic prints every time we hit the PRINT button.

print2 Desktop Printing 101

Please consider supporting this blog.

This blog really does need your support. All the information I put on these pages I do freely, but it does involve costs in both time and money.

If you find this post useful and informative please could you help by making a small donation – it would really help me out a lot – whatever you can afford would be gratefully received.

Your donation will help offset the costs of running this blog and so help me to bring you lots more useful and informative content.

Many thanks in advance.