More ISO Settings Misinformation

More ISO Settings Misinformation

This WAS going to be a post about exposure…….!

But, this morning I was on the Facebook page of friend where I came across a link he’d shared to this page which makes a feature of this:

%name More ISO Settings Misinformation

Please Note: I’m “hot linking” this image so’s not to be accused of theft!

This style of schematic for the Exposure Triangle is years old and so is nothing new.

When using FILM the ISO value IS a measure of sensitivity to light – that of the film, in other words its SPEED.  Higher ISO film is more sensitive to light than lower ISO film, and the increased sensitivity brings about larger ‘grain’ in the image.

When we talk ‘digital photography’ however the ISO value HAS NOTHING TO WITH SENSITIVITY TO LIGHT – of anything inside your camera, including the damn sensor.

ISO in digital cameras is APPLIED GAIN. Applied ‘after the exposure has been made’..after the fact…after Elvis has left the freaking building!

Your sensors sensitivity to light is FIXED and dictated by the size of the photosites that make up the sensor – that is, the sensor pixel pitch.

People who persist in leading you guys into thinking that ISO controls sensor sensitivity should be shot, or better still strapped over the muzzle of an artillery piece……..

The article then goes on to advise the following pile of horse crap:

Recommended ISO settings:

  • ISO 100 or 200 for sunny and bright daylight 
  • ISO 400 ISO for cloudy days, or indoors 
  • ISO 800 for indoors (without a flash) 
  • ISO 1600+ for very low light situations 

WTF??? What year are we in – 2007??

And this pile of new 2017 junk is on a website dedicated to a certain camera manufacturer who’s cameras have produced superb images at ISO settings way higher than the parameters stated above for ages.

Take this shot from a Canon 1DX Mk1 – old tech/off-sensor ADCs etc:

FW1Q4333 600x400 More ISO Settings Misinformation

Canon 1DX Mark 1 ISO 10,000 1/8000th @ f7.1 – click for the full size image.

ISO settings are at the bottom of the pile when it comes to good action photography – the overriding importance at all times is SHUTTER SPEED and AF performance.

I don’t care about ‘ISO noise’ anywhere near as much as I care about focus and freezing the action, and neither should you guys.

What have the above and below shots got in common – apart from the wildlife category?

 D4R3440 More ISO Settings Misinformation

Nikon D4 – a meagre ISO 3200 1/8000th @ f7.1 – click for full size image.

1/8000th shutter speed and an aperture of 7.1 – aperture for DoF and shutter speed to freeze the action – stuff the ‘noise’.

And speaking of ‘noise’ – there isn’t anywhere near enough to screw the shot up for stock sale even at full size, and I’ll tell you again, noise hardly prints at all!

Here’s another ‘old tech’ Canon 1DX Mk1 shot:

GX2R4727 More ISO Settings Misinformation

And here’s where the rubber really meets the road – low light 4000ISO  1/200th @ f6.3 – click for full size image.

I don’t really want to wheel the same shots out over and over but don’t forget the Canon 5D Mk4 Great Tit at 10,000ISO or 1DX Mk2 Musk Ox at 16,000ISO either!

Don’t get me wrong, when I want maximum Dynamic Range I shoot at base ISO, but generally you’ll never find me shooting at any fixed ISO other than base; other than when shooting astro landscapes.  Everything else is Auto ISO.

So a fan website, in 2017, is basically telling you not to use the ISO speeds that I use all the damn time – and they are justifying that with bad information.

Please people, 90% plus of what you see on the web is total garbage, please don’t take it as gospel truth until you check with someone who actually knows what they are talking about.

Do I know what I’m talking about, well, only you can judge that one.  But everything I do tell you can be justified with full resolution images – not meaningless little jpegs on a web site.

Anyway, that’s it – rant over!

As ever, if you like the info in this post hit the subscribe button. Hop over to my YouTube channel and subscribe there too and if you are feeling generous then a couple of bucks donation via PayPal to tuition@wildlifeinpixels.net would be gratefully appreciated!

Thanks Folks!

Camera ISO Settings

The Truth About ISO

Back in the days of ‘wet photography’, we had rolls and sheets of film that carried various ISO/ASA/DIN numbers.

ISO stands for International Standards Organisation

ASA stands for American Standards Association

DIN – well, that’s ‘Deutsches Institut für Normung’ or German Institute for Standardisation

ISO and ASA were basically identical values, and DIN = (log10)ISO x10 +1, so ASA/ISO 100 equated to DIN 21….nope, I’m not going to say anything!

These numbers were the film ‘speed’ values.  Film speed was critical to exposure metering as it specified the film sensitivity to light.  Metering a scene properly at the correct ISO/ASA/DIN gave us an overall exposure value that ensured the film got the correct ‘dose’ of light from the shutter speed and aperture combination.

Low ISO/ASA/DIN values meant the film was LESS sensitive to light (SLOW FILM) and high values meant MORE sensitivity to light (FAST FILM).

Ilford Pan F was a very slow mono negative film at ASA 50, while Ilford HP5 was a fast 400 ASA mono negative film.

The other characteristic of film speed was ‘grain’.  Correctly exposed, Pan F was extremely fine grained, whereas correctly exposed HP5 was ‘visibly grainy’ on an 8×10 print.

Another Ilford mono negative film I used a lot was FP4.  The stated ASA for this film was 125ASA/ISO, but I always rated it (set the meter ASA speed dial) to 100ASA on my 35mm Canon A1 and F1 (yup, you read that right!) because they both slightly over-metered most scenes.

If we needed to shoot at 1/1000th and f8 but 100ASA only gave us 1/250th at f8 we would switch to 400ASA film – two stops greater sensitivity to light means we can take a shutter speed two stops shorter for the same aperture and thus get our required 1/1000th sec.

But, what if we were already set up with 400ASA film, but the meter (set at 400ASA) was only giving us 1/250th?

Prior to the release of films like Delta 1600/3200 we would put a fresh roll of 400ASA film in the camera and set the meter to a whopping 1600ASA! We would deliberately UNDER EXPOSE Ilford HP5 or Kodak Tri-X by 2 stops to give us our required 1/1000th at f8.

The two stops underexposed film would then be ‘push processed’, which basically meant it was given a longer time in the developer.  This ‘push processing’ always gave us a grainy image, because of the manner in which photographic chemistry worked.

And just to confuse you even more, very occasionally a situation might arise where we would over expose film and ‘pull process’ it – but that’s another story.

We are not here for a history lesson, but the point you need to understand is this – we had a camera body into which we inserted various sensitivities of film, and that sometimes those sensitivities were chemically manipulated in processing.

That Was Then, This Is Now!

ISO/ASA/DIN was SENSITIVITY of FILM.

It is NOT SENSITIVITY of your DSLR SENSOR….!!! Understand that once and for all!

The sensitivity of your sensor IS FIXED.

It is set in Silicon when the sensor is manufactured.  Just like the sensitivity of Kodak Tri-X Pan was ‘fixed’ at 400ASA/ISO when it was made at the factory.

How is the sensitivity of a digital sensor fixed?  By the SIZE of the individual PHOTOSITES on the sensor.

Larger photosites will gather more photons from a given exposure than small ones – it’s that simple.

The greater the number of photons captured means that the output signal from a larger photosite is GREATER than the output signal from a smaller photosite for the same exposure value (EV being a combination shutter speed and aperture/f number).

All sensors have a base level of noise – we can refer to this as the sensor ‘noise floor’.

This noise floor is an amalgamation of the noise floors of each photosite on the sensor.

But the noise floor of each photosite on the sensor is masked/obscured by the photosite signal output; therefore the greater the signal, the larger the signal to noise (S/N) ratio is said to be.

In general, larger photosites yield a higher S/N ratio than smaller ones given the same exposure.

This is why the Nikon D3 had such success being full frame but just over 12 megapixels, and it’s the reason that some of us don’t get overly excited about seeing more megapixels being crammed into our 36mm x 24mm sensors.

Anyway, the total output from a photosite contains both signal and noise floor, and the signal component can be thought of as ‘gain’ over the noise floor – natural gain.

As manufacturers put more megapixels on our sensors this natural gain DECREASES because the photosites get SMALLER – they have to in order to fit more of them into the finite sensor area.

Natural gain CAN be brought back in certain sensor designs by manipulating the design of the micro lenses that sit on top of the individual photosites. Re-design of these micro lenses to ‘suck in’ more tangential photons – rather like putting a funnel in a bottle to make filling it easier and more efficient.

There is a brilliantly simple illustration of how a sensor fits into the general scheme of things, courtesy of digital camera world:

%name Camera ISO Settings

The main item of note in this image is perhaps not quite so obvious, but it’s the boundary between the analogue and digital parts of the system.

We have 3 component arrays forward of this boundary:

  1. Mosaic Filter including Micro Lenses & Moire filter if fitted.
  2. Sensor Array of Photosites – these suck in photons and release proportional electrons/charge.
  3. Analogue Electronics – this holds the charge record of the photosite output.

Everything forward of the Analogue/Digital Converter – ADC – is just that, analogue! And the variety of attributes that a manufacturer puts on the sensor forward of this boundary can be thought of mostly as modifying/enhancing natural gain.

So What About My ISO Control Settings Andy?

All sensors have a BASE ISO. In other words they have an ISO sensitivity/speed rating just like film!  And as I said before THIS IS A FIXED VALUE.

The base ISO of a sensor photosite array can be defined as that ISO setting that yields the best dynamic range across the whole array, and it is the ISO setting that carries NO internal amplification.

Your chosen ISO setting has absolutely ZERO effect on what happens forward of the Analogue/Digital boundary – NONE.

So, all those idiots who tell you that ISO effects/governs exposure are WRONG – it has nothing to do with it for the simple reason that ISO effecting sensor sensitivity is a total misconception….end of!

Now I’ll bet that’s going to set off a whole raft of negative comments and arguments – and they will all be wrong, because they don’t know what they’re talking about!

The ‘digital side’ of the boundary is where all the ‘voodoo’ happens, and it’s where your ISO settings come into play.

At the end of an exposure the Analogue Digital Converter, or ADC, comes along and makes a ‘count’ of the contents of the ‘analogue electronics’ mosaic (as Digital Camera World like to call it – nice and unambiguous!).

Remember, it’s counting/measuring TOTAL OUTPUT from each photosite – and that comprises both signal and noise floor outputs.

iso1 900x900 Camera ISO Settings

If the exposure has been carried out at ‘base ISO’ then we have the maximum S/N ratio, as in column 1.

However, if we increase our ISO setting above ‘base’ then the total sensor array output looks like column 2.  We have in effect UNDER EXPOSED the shot, resulting in a reduced signal.  But we have the same value for the noise floor, so we have a lower S/N ratio.

In principal, the ADC cannot discriminate between noise floor and signal outputs, and so all it sees in one output value for each photosite.

At base ISO this isn’t a problem, but once we begin to shoot at ISO settings above base, under exposing in other words, the cameras internal image processors apply gain to boost the output values handed to it by the ADC.

Yes, this boosts the signal output, but it also amplifies the noise floor component of the signal at the same time – hence that perennial problem we all like to call ‘high ISO noise’.

So your ISO control behaves in exactly the same way as the ‘gain switch’ on a CB or long wave radio, or indeed the db gain on a microphone – ISO is just applied gain.

Things You Should Know

My first digital camera had a CCD (charge coupled device) sensor, it was made by Fuji and it cost a bloody fortune.

Cameras today for the most part use CMOS (complimentary metal oxide semi-conductor) sensors.

  • CCD sensors create high-quality, low-noise images.
  • CMOS sensors, traditionally, are more susceptible to noise.
  • Because each photosite on a CMOS sensor has a series of transistors located next to it, the light sensitivity of a CMOS chip tends to be lower. Many of the photons striking the sensory photosite array hit the transistors instead of the photosites.  This is where the newer micro lens designs come in handy.
  • A CMOS sensor consumes less power. CCD sensors can consume up to 100 times more power than an equivalent CMOS sensor.
  • CMOS chips can be produced easily, making them cheaper to manufacture than CCD sensors.

Basic CMOS tech has changed very little over the years – by that I’m referring to the actual ‘sensing’ bit of the sensor.  Yes, the individual photosites are now manufactured with more precision and consistency, but the basic methodology is pretty much ‘same as it ever was’.

But what HAS changed are the bits they stick in front of it – most notably micro-lens design; and the stuff that goes behind it, the ADC and image processors (IPs).

The ADC used to be 12 bit, now they are 14 bit on most digital cameras, and even 16 bit on some.  Increasing the bit depth accuracy in the ADC means it can detect smaller variations in output signal values between adjacent photosites.

As long as the ‘bits’ that come after the ADC can handle these extended values then the result can extend the cameras dynamic range.

But the ADC and IPs are firmware based in their operation, and so when you turn your ISO above base you are relying on a set of algorithms to handle the business of compensating for your under exposure.

All this takes place AFTER the shutter has closed – so again, ISO settings have less than nothing to do with the exposure of the image; said exposure has been made and finished with before any ISO applied gain occurs.

For a camera to be revolutionary in terms of high ISO image quality it must deliver a lower noise floor than its predecessor whilst maintaining or bettering its predecessors low ISO performance in terms of noise and dynamic range.

This where Nikon have screwed their own pooch with the D5. At ISOs below 3200 it has poorer IQ and narrower dynamic range than either the D4 or 4S.  Perhaps some of this problem could be due to the sensor photosite pitch (diameter) of 6.45 microns compared to the D4/4S of 7.30 microns – but I think it’s mostly due to poor ADC and S/N firmware; which of course can be corrected in the future.

Can I Get More Photons Onto My Sensor Andy?

You can get more photons onto your sensor by changing to a lens that lets in more light.

You might now by thinking that I mean switching glass based on a lower f-number or f-stop.

If so you’re half right.  I’m actually talking about t-stops.

The f-number of a lens is basically an expression of the relationship between maximum aperture diameter and focal length, and is an indication of the amount of light the lens lets in.

T-stops are slightly different. They are a direct indicator of how much light is transmitted by the lens – in other words how much light is actually being allowed to leave the rear element.

We could have two lenses of identical focal length and f-number, but one contains 17 lens elements and the other only 13. Assuming the glass and any coatings are of equal quality then the lens with fewer elements will have a higher transmission value and therefore lower T-number.

As an example, the Canon 85mm f1.2 actually has a t-number of 1.4, and so it’s letting in pretty much HALF a stop less light than you might think it is.

In Conclusion

I’ve deliberately not embellished this post with lots of images taken at high ISO – I’ve posted and published enough of those in the past.

I’ve given you this information so that you can digest it and hopefully understand more about how your camera works and what’s going on.  Only by understanding how something works can you deploy or use it to your best advantage.

I regularly take, market and sell images taken at ISO speeds that a lot of folk wouldn’t go anywhere near – even when they are using the same camera as me.

The sole reason I opt for high ISO settings is to obtain very fast shutter speeds with big glass in order to freeze action, especially of subjects close to the camera.  You can freeze very little action with a 500mm lens using speeds in the hundredths of a second.

Picture buyers love frozen high speed action and they don’t mind some noise if the shot is a bit special. Noise doesn’t look anywhere near as severe in a print as it does on your monitor either, so high ISO values are nothing to shy away from – especially if to do so would be at the expense of the ‘shot of a lifetime’.

More Thoughts on the Nikon D5

More Thoughts on the Nikon D5

Nikon D5 banner 577x400 More Thoughts on the Nikon D5

Okay, so the Nikon D5 has started to slowly trickle into the hands of people now (though sadly not those belonging to yours truly) and yesterday I was sent a link to some downloadable D5 RAW files.

That link is HERE for those of you that might want a look for yourself.

If you have received this post via email PLEASE view it on the blog itself.

Also, as a matter of interest, Nikon have made the D5 User Manual available HERE.

As I’ve said in earlier posts, I’m quite excited at the thought of the new AF system giving the Nikon shooter access to more Canon-esque controls, but image quality in terms of sensor output and the recorded .NEF are always paramount in my mind.

So I jumped all over the above-linked RAW files, but I have to say that looking at them in Lightroom (neutralised of course as per my previous post HERE) I’m not as overly enamoured as I thought I was going to be.

I’ve seen this camera called ‘The New Lord of Darkness’ with much play being made of its high ISO capability, so let’s have a look at that shall we.  ISO range is 100 to 102,000 expandable to 50 and 3,276,800 – ISO stupid and then some!

Before we go any further, I suspect that the downloadable files are Lossless Compressed!

Want to see what 3,276,800ISO looks like?

All shots are by a user named Andy (not me) posted on NikonGear.net – thanks go to him for sharing.

D5D 1182 2 600x400 More Thoughts on the Nikon D5

ISO 3,286,800 – Image is NOT full resolution as it’s too big for WordPress!

D5D 1182 3 600x400 More Thoughts on the Nikon D5

ISO 3,286,800 or H5 – full resolution crop – CLICK to view at full size.

This image is, honestly, unusable SO WHY charge you the buyer for the ability to produce it??

Let’s have a look at the high native ISO 102,400:

D5D 1177 More Thoughts on the Nikon D5

Nikon D5 highest native 102,400 ISO – click for full rez view.

Okay, so in certain circumstances this image would be useful for press reproduction, and I can see the appeal for photojournalists – this level of performance will earn them money, and lots of it.

But I suspect that 75%+ of all global D5 purchasers in its first 12 months will NOT benefit from this performance because they are not in that market place. If you produce weddings shots that look like this then you’re going to get sued up the Ying Yang for sure.

What is interesting is a link on Nikon Rumours which was kindly sent to me yesterday by Paul Atkins:

D4vD5 DR 900x364 More Thoughts on the Nikon D5

Photographic Dynamic Range comparison of Nikon D4 and Nikon D5.

This is a ‘live graph’ which you can access directly via this link HERE

This is a comparison of PDR, not EDR, and you will not find the D5 listed at DXO Mark at this moment in time. If you want to get your head around the difference between PDR and EDR then click HERE or HERE. But be warned, MATHS ALERT!

Below 1600 ISO the D5 has a significantly lower PDR than the D4, putting it very much in line with the Canon 1DX at <1600ISO – see HERE.

To my mind the D5 is an all-action camera with good low light capabilities; as is/was the D3 in its time, D4 and D4s and Canons 1DX.

As such, lower ISO performance is not really important – it’s a question of ‘horses for courses’ and the right tool for the job.  But the fact that the PDR is lower came as a surprise.

Time was, not so long ago, that I was ‘capped’ at sub 800 ISO for wildlife/action photography – the D3 put paid to that and 1200 to 1600 ISO became my working values when needed.

The D4 and Canon 1DX shifted the goal posts again – 3200 ISO became a standard AND both cameras had AutoISO that worked perfectly.

Nobody with a working brain chooses to work at high ISOs unless they are driven to do so by a need for high shutter speeds in low light – no matter how well a camera sensor functions, image quality will always increase with decreasing ISO.

So examination of the above PDR curves clearly indicate that the true advantage of the D5 over the D4 is on average around 1.3 stops above 1600 ISO – which is a good thing, but it’s not exactly what I’d call revolutionary.  We experience pretty much the same increase with every Nikon D FX release.

If PDR increases then the Signal to Noise ratio – S/N – pretty much appears to increase by the same value, so a visual comparison of D4 and D5 images shot at higher than 1600 ISO will show around 1.3Ev to 1.5Ev of reduced ISO noise.

What I do like is the IQ improvements at 8000 ISO and above.  8000 ISO on a D4 is bad, and its top native 12800 ISO is awful.  Based on the downloaded raw files, anyone could process a D5 12800 ISO image at full resolution to pass QC at ANY stock agency – just go and download those RAWS on the link at the top of the post and see for yourself.

25,600 ISO – well I might be tempted to down-res those by perhaps 1000 to 1500 pixels on the long edge to help with noise reduction a bit, and chucked onto A3 or A3+ print you would never really notice the noise.

Do I like what I see – yes I do!

Is the D5 the new ‘Lord of Darkness’ – no it bloomin’ well isn’t!  Lord of Low Light – quite possibly.  The ISO H1 to H5 images go from questionable to crap in my opinion.

Like the Canon 1DX, I’m not impressed at lower ISO values than 1600 – I can get the same or better performance with a D4 or 4S – admittedly though with a lower pixel count.

So overall Andy, does the D5 impress?  Well, still being in a hands-off situation I’m not going to commit to a full answer there.  When all is said and done, the AF performance will be the key issue for me – a high DR/low noise image of an out of focus subject in no use to me – or anyone else for that matter!

The Way I See Things As They Stand At This Very Moment.

The KING of low ISO with high resolution DSLRs is the Nikon D800E – but it’s not without its limitations. And before you start screaming 5DS at me – it’s a nail, go away..

The best all-round VFM DSLR is the Nikon D810 – a proper jack of all trades who’s only weakness is the occasionally questionable Nikon AF.

The best DSLR autofocus for action is without doubt the Canon 1DX – fabulous AF, crap ergonomics, crap sensor.

The best DSLR sensor for action is the Nikon D4 or 4S – great ergonomics, great sensor, sometimes dubious AF.

But, going on the raw files I’ve downloaded, I strongly suspect that the D5 is going to have the best action sensor title stitched up and dethrone the D4/4S.

Will it dethrone the Canon 1DX in the action AF department – no idea is my truthful answer.  I suppose anything is possible, but if it did, would the soon-to-be-released 1DXMk2 take the throne back – quite possibly.

If you have found this post useful please consider donating a little, or a lot, by clicking the Donate Button.