ISO - Waste of time when shooting RAW?

[sk66]

As you know, ETTR works because you have (significantly) more bit depth at the right of the histogram than you do at the left.

I think bit depth/bit accuracy is something of red herring here. Light and color (exposure) are logarithmic just as bit depth is... i.e it requires less difference at the low end, and it requires more difference at the high end in order to generate the same level of difference in output (i.e. to be discernible).

The whole point of any/all of this is managing/optimizing sensor performance, and in particular the DR capabilities. In order to do that you first have to understand the DR capability of a sensor is dependent on the sensor having some pixels at FWC (max brightness w/o clipping) and other pixels just above the noise floor (min brightness w/o clipping).
Think of this as the length of the ladder, the total DR which always goes from pure black to pure white (i.e. 7 stops with 5 stops distinguished in-between; the 5 stop histogram). The DR capability of the sensor in stops of DR is how many steps it can discern between it's min/max sensitivity... think of these as rungs on the ladder.

Now you can shift this ladder up/down but you cannot make it longer.
However, you can make it shorter by sinking some of the bottom rungs into darkness. If you do not record any pixels at FWC and you record more below the minimum discernible, the DR decreases both in overall length (min/max, because max wasn't used), and in the number of steps between the min max level recorded. And every other sensor capability also reduces because you have not collected as much data/accuracy... i.e. light.

None of this really has anything to do with ISO invariance, ETTR, ITTR, etc... it's simply a matter of collecting as much light/information as possible. All of those other concepts are simply what you can do with it after the fact. ISO is *not* collecting light, it is the opposite. And in general, all sensor performance characteristics will decline at a near 1:1 rate as ISO is increased and less light/data is received (OK, that is a pretty vast over generalization... but it makes the point and it isn't far off).

It is also relevant to understand that most of the gains in CMOS sensor performance have been achieved by increasing efficiency and reducing the noise floor. I.e. almost all of the gains in DR/color etc are achieved at the dark end, and not at the bright end. In fact, with the trend towards smaller pixels there is a reduction in FWC which will tend to reduce the DR capability.

So, to simplify and reiterate... if you want maximum IQ you *must* record as much actual light/data as possible w/o clipping what is important to you/your image (using SS/Ap, not ISO). Call it ETTR/ETTL/whatever, it doesn't really matter... it's the same thing (filling the histogram/DR/capacity).

 

[Fraser Euan White]

Another interesting article: (https://improvephotography.com/34818/iso-invariance/)

Copied as some posters don't read links:
ISO Invariance: What it is, and which cameras are ISO-less

In Gear by Jim Harmer61 Comments

ISO invariance is an exciting new frontier in photography, and I've been experimenting with it extensively over the last few days to see if it's a technique that I can add to my photography tool belt (Fine… I admit it. I've never even worn a tool belt. I'm the worst handyman on the planet.)

In essence, ISO invariance allows the photographer to entirely skip over the ISO when setting the exposure and never changing it, but still being able to take full advantage of the low light performance of the camera. It's still a brand new concept (the first mention I could find of it online was in 2011), and really nobody started talking about it until DPReview started publishing more information about it 6 months ago.

What is ISO Invariance (An ISO-less Camera)?
The short answer is that ISO invariance means that a camera will produce the exact same image quality by staying at ISO (or whatever the base ISO is on the camera) and dramatically underexposing the photo and then brightening it up again in Lightroom, as if you had shot the camera at the proper ISO in the first place.

It makes your head spin for a minute, but don't worry. We'll go through lots of examples and it'll make sense shortly.

Let's suppose you want to go out and shoot a photo of the stars. As a starting place, suppose we set our camera settings to f/2.8, 20″ shutter speed, and ISO 3200. Those are pretty standard settings for night photography, and they'll likely produce a nice image. But what if you kept the shutter speed and aperture the same, but dropped your ISO to 100? The resulting photo is dramatically underexposed, but if you take that underexposed file into Lightroom and bring up the exposure, it suddenly looks identical to the photo shot at ISO 3200. Increasing the exposure in Lightroom introduces noise, but just the same amount of noise as the high ISO would have introduced.

Thus, we say this camera is ISO invariant (“invariant” means something that remains unchanged despite different circumstances), or sometimes photographers say the camera is ISO-less.



What Cameras Are ISO Invariant?
First of all, a disclaimer. Just because a camera fits in the “ISO invariant” category below doesn't mean it's precisely the same thing to shoot at ISO 100 and brighten vs shooting at a high ISO. There are slight differences in how the files look with some benefits and drawbacks to each. What we're focused on here is the levels of noise and reasonable dynamic range and highlight/shadow detail.

So you can't PROVE that any camera fits in any of these camps, but I made my best judgment call given the test results we got after I polled the Improve Photography Podcast listeners and asked them to send me their raw file tests using many many different cameras.

Cameras that are ISO Invariant

• Sony A7RII (Much better highlight detail from shooting at base and brightening later, but lose a a slight amount of shadow detail. I might even dare say that noise is handled JUST A TINY TINY bit BETTER on the brightened picture than on the high-ISO shot.)
• Fuji XT1 (This is my personal camera. I switched from Nikon to Fuji. It's probably the most iso-less camera out of all those that I tested.)
• Fuji X100
• Fuji XE1
• Nikon D810 (Relying on data from DPReview. The Sony A7R uses the same sensor, so I would ASSUME that it is as well.)
• Nikon D750 (Only did one test with this, but appears to be entirely ISO invariant. Would like to test more)
• Nikon D7100 (Tested only at base vs ISO 800, but the noise pattern is identical)
• Nikon D5500 (I did not personally test this one. Relying on data from DPReview)
• Pentax K5 (At ISO 800 vs base ISO, you can't tell any difference. Very high ISOs not tested)

Cameras that are Somewhat ISO Invariant

• Olympus OMD-EM1 (Tough call. Detail and contrast are definitely lost when brightening in post, but noise appears to be reduced quite a bit on the brightened image. I'd like to do more testing.)
• Olympus OMD-EM5 II (Difference is indistinguishable when zoomed out, but when you zoom in, the higher ISO photo is VERY VERY slightly better in terms of noise and contrast. The 40mp mode brings the contest even closer.)
• Sony A7S (I was interested to see this one. The noise pattern on the brightened image is close to the high ISO shot. However, the brightened image lost a SURPRISING amount of contrast).
• Sony Nex 7 (This one is really close to being ISO invariant. The noise is about the same, but contrast is lost on the brightened image. Very close to being ISO-less.)

Cameras that are NOT ISO Invariant

• Canon 5D Mark III (Not even CLOSE! Nick Page tested this one for us and it looks really bad when you shoot low and brighten later.)
• Canon 6D (Not even close, and the camera did a horrible job of selecting the white balance in the under-exposed shot.)
• Canon 70D and Canon 60D (Not too bad, but it's still much better to shoot at the higher ISO. Horrible white balance in the underexposed shot.)
• Canon 7D (Not nearly as bad as the 5DIII, and you can't tell the difference with the naked eye at ISO1600, but when you zoom in it's obvious that the higher ISO shot is cleaner. White balance not good in the underexposed photo.)

Thank you to the following Improve Photography readers from all around the world who contributed raw files for this test: Dale Mellor, Nick Page, Darin Mellor, Linda Maier, A Zelkanovic, Ryan Fritsch, Tristan Davies, Benjamin Boynton, Julio Debeux, Jenn Dijk, Robert Connor, Stephen Tillman, Sarah Scully, Najib Mahmud, Mark Franks, Clarence Hagler, Nelson Tapias, and Wesley York.


THE ISO DIAL ON THE FUJI XT1, WHICH IS PROBABLY THE MOST ISO INVARIANT CAMERA WE TESTED.

Why Would Anyone Want to Use This?
There are lots and lots of reasons why this would be a fantastic technique in certain situations. It's not something I'd use every day, but it's certainly a technique I will implement in my night photography.

One of the reasons is that by brightening the exposure in post, you can selectively brighten some areas and leave others darker. This reduces the noise in some areas of the image, whereas if you set the ISO high in camera, it makes all of the photo have the higher amount of noise.

Another reason why you'd want to shoot an image at base ISO and brighten later is when you are concerned about preserving highlight detail. Suppose you're in Time Square in New York and you want to take a shot of the colorful lights above the streets at night. If you shoot at a high ISO to properly expose, there isn't enough dynamic range to properly preserve highlights and still expose the shadows. However, if you do this after the fact, you could easily brighten the image without blowing out highlight detail in the bright signs.

Another reason is when shooting night photography. It can be difficult to judge how much noise is present in a photo when you're just looking at the tiny preview on the LCD of the camera. Many times I've ruined night photography shoots because I pushed the ISO a little too high for the camera. If I would have simply shot the whole night at ISO 100 and brightened later, this would not have happened.

The limitation to shooting at base ISO and brightening later, however, is that you'll see a black preview on the back of your LCD all night. Makes it kinda tough to judge the composition! So I plan on flipping back and forth. Use high ISOs on my Fuji XT1 for getting the composition, and then once I have the shot looking how I want, I'll shoot one at base ISO (which is 200 on the Fuji XT1 but 100 on most cameras) and keep that one for the official shot.

 

[Gaz J]

Don't read copies from links either.

 

[Phil V]

Copied as some posters don't read links:

So should you amend the thread title to...
ISO - waste of time when shooting Raw with a small number of cameras in a limited number of situations.

Or
ISO Invariance, is it a game changer

 

[troutfisher]

So we have had 4 pages of comments when the last para in the OP's post above says what its all about and when its most beneficial -horses for courses!

 

[Fraser Euan White]

So should you amend the thread title to...
ISO - waste of time when shooting Raw with a small number of cameras in a limited number of situations.

Or
ISO Invariance, is it a game changer

Maybe...........probably or even all three fit

The discussion thread has made me research the topic and learn. I would certainly find the technique useful from what I have read and hopefully others/in the future may also consider this.

 

[boyfalldown]

So should you amend the thread title to...
ISO - waste of time when shooting Raw with a small number of cameras in a limited number of situations.

Or
ISO Invariance, is it a game changer

confused by all this. I just tried a quick experiment to see if I got anything like as good results using base iso and then adjusting in post (I realise I'm not as good as some with LR, but I'm far from a slouch with it) vs exposing as I normally would. I'm going to stick with exposing properly for now at least

 

[gman]

Erm... probably yes in practise, but no in theory. HDR technique involves making multiple exposures, gathering progessively more and more light/photons each time. You can't beat that, but it's different (and way more laborious).

In practical terms though, ISO-invariance allows you to a) pull an enormous amount of detail from dark shadows (like raising ISO), but also b) you can adjust exposure so that highlights are retained and not blown (unlike raising ISO, and also a serious downside of ETTR technique). You could also add c) cock-up recovery.

There is a penalty for all this, but overall the impact on image quality is minimal while the practical benefits are huge.

Sorry, I probably didn't word my post very well, I was meaning more along the lines of spot editing a scene which has a wide dynamic range, perhaps something like a scene where most of it is very bright but the subject of interest is in the shadow but if you increase the ISO in camera in order to expose the subject correctly you could blow out the surrounding highlights, however, with ISO-invariance would you not have far more control over the exposure in any part of the scene without effecting the rest?

Just did a test and the Sony A6000 doesn't appear to be an ISO-Invariant camera

But something I was wondering, when the scene was hideously underexposed and I went to focus on something the screen suddenly exposes correctly for a second as it acquires focus and then goes back to being hideously underexposed, which subsequently prevented the continuous autofocus from working! So how will continuous autofocus work with the ISO-Invariant technique?

 

[Muzzieman]

Having read through this thread I fail to see how this technique is of any benefit in the real world. I can’t imagine me showing a client(particularly a new one) an under exposed image and asking them to trust that it will be all ok in the edit. Clients want to see what, or at least something close to what they are paying for! Also if you are going to have to do an extensive edit to get the result you want you may as well do it properly and bracket exposures. Plus I know my camera is incapable of this. As a canon 5d mk 3 owner noise levels when you push a file too far are horrific and completely in unusable. As technology progresses this may become the norm but technology should never be relied on exclusively. Without the proper skill and knowledge to create images correctly you will fail at some point.

 

[Fraser Euan White]

Without the proper skill and knowledge to create images correctly you will fail at some point.

Yes, the Canon 5D MK3 is not suited to this technique (apparently).

For those with Cameras that are; surely the definition of 'correct' is to achieve the best possible finished image?

From the article I posted:

Why Would Anyone Want to Use This?
There are lots and lots of reasons why this would be a fantastic technique in certain situations. It's not something I'd use every day, but it's certainly a technique I will implement in my night photography.

One of the reasons is that by brightening the exposure in post, you can selectively brighten some areas and leave others darker. This reduces the noise in some areas of the image, whereas if you set the ISO high in camera, it makes all of the photo have the higher amount of noise.

Another reason why you'd want to shoot an image at base ISO and brighten later is when you are concerned about preserving highlight detail. Suppose you're in Time Square in New York and you want to take a shot of the colorful lights above the streets at night. If you shoot at a high ISO to properly expose, there isn't enough dynamic range to properly preserve highlights and still expose the shadows. However, if you do this after the fact, you could easily brighten the image without blowing out highlight detail in the bright signs.

Another reason is when shooting night photography. It can be difficult to judge how much noise is present in a photo when you're just looking at the tiny preview on the LCD of the camera. Many times I've ruined night photography shoots because I pushed the ISO a little too high for the camera. If I would have simply shot the whole night at ISO 100 and brightened later, this would not have happened.

 

[HoppyUK]

Sorry, I probably didn't word my post very well, I was meaning more along the lines of spot editing a scene which has a wide dynamic range, perhaps something like a scene where most of it is very bright but the subject of interest is in the shadow but if you increase the ISO in camera in order to expose the subject correctly you could blow out the surrounding highlights, however, with ISO-invariance would you not have far more control over the exposure in any part of the scene without effecting the rest?

Yes.

Just did a test and the Sony A6000 doesn't appear to be an ISO-Invariant camera

But something I was wondering, when the scene was hideously underexposed and I went to focus on something the screen suddenly exposes correctly for a second as it acquires focus and then goes back to being hideously underexposed, which subsequently prevented the continuous autofocus from working! So how will continuous autofocus work with the ISO-Invariant technique?

That's a function of live-view AF rather than ISO-invariance. They're not related. There are quite a few difficulties to be sorted out if ISO-invariance is to become practical and easy, but turning up the sensor gain just for AF purposes could still work in the same way it does now.

 

[sk66]

Copied as some posters don't read links:

For those with Cameras that are; surely the definition of 'correct' is to achieve the best possible finished image?

A decent article I can largely agree with... The main thing to take out of it is that ISO invariant does **NOT** mean it performs better at base (or any) ISO when underexposed... it performs exactly the same as if it had been exposed correctly using a higher ISO... and that's because it receives the same amount of actual light in both cases.

However, I disagree with most of the examples where he tries to explain how it is useful. The ONLY case where this technique/characteristic is useful, is when you *must* underexpose a portion of the image you care about in order to retain highlights you also care about... I.e. ONLY when selective exposure increase in post is better than a global increase at the time of capture.

The other examples are basically wrong... if a camera/sensor is truly ISO invariant (and even many/most that are not), the "ISO noise" characteristics are easily eliminated by selective/global exposure reduction in post... in fact, this characteristic/behavior is so common it leads to the even more problematic ITTR (ISO To The Right) concept.

 

[Fraser Euan White]

A decent article I can largely agree with... The main thing to take out of it is that ISO invariant does **NOT** mean it performs better at base (or any) ISO when underexposed... it performs exactly the same as if it had been exposed correctly using a higher ISO... and that's because it receives the same amount of actual light in both cases.

However, I disagree with most of the examples where he tries to explain how it is useful. The ONLY case where this technique/characteristic is useful, is when you *must* underexpose a portion of the image you care about in order to retain highlights you also care about... I.e. ONLY when selective exposure increase in post is better than a global increase at the time of capture.

The other examples are basically wrong... if a camera/sensor is truly ISO invariant (and even many/most that are not), the "ISO noise" characteristics are easily eliminated by selective/global exposure reduction in post... in fact, this characteristic/behavior is so common it leads to the even more problematic ITTR (ISO To The Right) concept.

Steven, can I thank your for your time and efforts during this thread to explain your points of view/experience - it is much appreciated & welcomed

 

[HoppyUK]

A decent article I can largely agree with... The main thing to take out of it is that ISO invariant does **NOT** mean it performs better at base (or any) ISO when underexposed... it performs exactly the same as if it had been exposed correctly using a higher ISO... and that's because it receives the same amount of actual light in both cases.

However, I disagree with most of the examples where he tries to explain how it is useful. The ONLY case where this technique/characteristic is useful, is when you *must* underexpose a portion of the image you care about in order to retain highlights you also care about... I.e. ONLY when selective exposure increase in post is better than a global increase at the time of capture.

The other examples are basically wrong... if a camera/sensor is truly ISO invariant (and even many/most that are not), the "ISO noise" characteristics are easily eliminated by selective/global exposure reduction in post... in fact, this characteristic/behavior is so common it leads to the even more problematic ITTR (ISO To The Right) concept.

I think there's another way to use it, more of a half-way house, for me at least. I don't need or want 20-stops of dynamic range that makes everything look like horrendous HDR. But I do want the ability to pull clean and relatively noise free detail from the shadows, and I certainly want a normal-ish LCD image to work with.

So expose more or less as normal. Raise ISO and get a decent-looking LCD image rather than a completely useless dark void. Maybe under-expose a little to retain highlights, but nothing like six stops or whatever. Then pull up the shadow detail in post - there's still loads to be had. It looks gorgeous, and stays natural. By raising ISO above base/native level, it's not exploiting every drop of potential from both ends of the range, but it's still much more than with a non-ISO-invariant sensor, requires almost no re-learning and involves minimal operational compromises.

 

[sk66]

I think there's another way to use it, more of a half-way house, for me at least. I don't need or want 20-stops of dynamic range that makes everything look like horrendous HDR. But I do want the ability to pull clean and relatively noise free detail from the shadows, and I certainly want a normal-ish LCD image to work with.

So expose more or less as normal. Raise ISO and get a decent-looking LCD image rather than a completely useless dark void. Maybe under-expose a little to retain highlights, but nothing like six stops or whatever. Then pull up the shadow detail in post - there's still loads to be had. It looks gorgeous, and stays natural. By raising ISO above base/native level, it's not exploiting every drop of potential from both ends of the range, but it's still much more than with a non-ISO-invariant sensor, requires almost no re-learning and involves minimal operational compromises.

I think I can agree with all of that... I don't really see a significant difference.

There is the very real reality of when a scene does not exceed the capability of the sensor... if you are not commonly taking strongly backlit images the chances of this ISO invariance being of real/major benefit are minimal. How often do you see a histogram packed in the middle or to one side? Probably much more often than you see a full/packed histogram edge to edge. And in those cases the maximum benefit will be generated by combining multiple images/exposures when practicable (i.e a true extension of DR), and not using this invariance characteristic (there is a difference between exposure blending/DR extension and HDR tone mapping).

I think the idea of a usable LCD review jpeg should not be underestimated. The ability to review/refine exposure/DOF/focus is one fo the main benefits of digital... Yeah, we got by without it with film, but that is exactly the reason I would not revert to film these days. I've wasted entire rolls of film because I guessed wrong somewhere...these days I seldom get it wrong for more than a few images.

And then we need to consider what is ISO invariance in actuality. IME using the D8xx (D810), and most every other Nikon prior, the main issue is when recording dark images... those are the images that benefit the most from pushing the exposure to the right (not with ISO). IMO (no scientific basis) there is no such thing as universal ISO invariance. There is a point where the tradeoffs far outweigh any benefit with every camera. And a D810 image that looks like s*** at ISO 6400 is still going to look like s*** exposed at ISO 100 and pushed 6 stops in post... there is no free ride...

 

[Devoted Lens]

This is the biggest advantage! Set your shutter speed/aperture to a value you want, so if photographing a fast moving subject shoot at a high shutter speed, pick your aperture for DoF and leave ISO at 100 - correct the exposure in post

Surely this ALL depends on (as others have said) what camera/sensor you have, and what type of photography you're doing? If you are shooting landscapes, then you will generally have more time to mess about with manual settings and getting it exactly how you want it, but if for example you are in a fast-paced situation you are probably going ot need to work in Program to choose the aperture you want and let the camera set the shutter speed and ISO itself to get the best result?

I found myself in this exact situation two days ago, a high-ranking member of the Turkish army was visiting and I had about 3 seconds of clear air to capture him before he was surrounded by other heads blocking my view. I therefore whacked my camera into P, set my aperture nice and low and let the camera up the ISO to about 300. I wouldn't have had time to set the aperture and shutter speed just to leave my ISO at base.

And anyway, in most photos noise is not really an issue on modern cameras unless you're quite high up on the ISO?

Sorry but this all sounds a bit gash and radical to me.

 

[TheTimeChamber]

This whole thread whiffs of 'Why should I get it right in camera, when I can just use Lightroom/Photoshop to get it right for me after the fact'

I'd prefer to spend less time at the computer editting the files, and more time outside taking the photo. This whole method would add a hugely boring step sitting at a desk.

 

[Deleted sulking member 63079]

ISO invariance is great for weddings, I typically under expose by 2/3 - 1 stop to make sure I preserve highlights, knowing boosting the exposure in darker areas isn't going to reduce image quality in post.

 

[Fraser Euan White]

This whole thread whiffs of 'Why should I get it right in camera, when I can just use Lightroom/Photoshop to get it right for me after the fact'

I'd prefer to spend less time at the computer editting the files, and more time outside taking the photo. This whole method would add a hugely boring step sitting at a desk.

You need to shoot JPEG then! All RAW files have to be edited; if you don't enjoy editing then Jpegs are for you.

If you think ISO invariance ''smacks' of getting it wrong in camera you are very wrong; it is a deliberate step to improve the final photograph.

 

[riddell]

If you think ISO invariance ''smacks' of getting it wrong in camera you are very wrong; it is a deliberate step to improve the final photograph.

Whatever you may think or try to argue I guarantee that there are loads of crappy photographers out there getting extremely excited at this technology for the simple reason that you don't have to get it right in camera. They are lazy and desperate for anything to automate their process without having to learn anything.

Personally I only see it as an advantage in an emergency situation if you ever make a mistake.

 

[TheTimeChamber]

No, it doesn't. I shoot RAW to preserve the best possible detail and add my own post-processing techniques if needed, but I have a workflow that means I don't spend hours on each image. I prefer to add little tweaks, rather than bang the sliders to the right.

From the link I read when I googled ISO invariance (https://improvephotography.com/34818/iso-invariance/), it appeared to me to make little difference if you shot at 100 and edit after, or 3200 and don't edit. I don't see why I would shoot everything at ISO 100 and potentially under expose it, only to have to then edit it later on the computer. I also cannot see how this would improve the photos when there is no discernible difference between shooting at the base ISO and the ISO you need (when shot with ISO invariant cameras). Six of one, half a dozen of the other. This just seems to me to want to bread lazy photography techniques where you don't worry about one of the most important aspects of photography, exposure.

Footnote: I shoot with a D750, which is apparently an ISO invariant camera. This isn't something I have tried, but I have noticed that it has an awesome capability to pull detail out of shadows. Something that is very useful when I have mucked the exposure up in a high contrast scene.

 

[sk66]

ISO invariance is great for weddings, I typically under expose by 2/3 - 1 stop to make sure I preserve highlights, knowing boosting the exposure in darker areas isn't going to reduce image quality in post.

Sorry, but this isn't quite right... it may not reduce the IQ enough to be problematic, or maybe not enough to even notice. But underexposure (lack of light) always reduces the max IQ. That said, underexposing so that the wanted highlights are w/in the histogram is good practice (basically ETTR). And if the SS/Ap are set optimally and the only variable is ISO, then it probably doesn't much matter either way.

Another thing about ISO invariance, it doesn't necessarily mean the camera/sensor performs particularly well in regards to gathering light/noise, it just means the ISO doesn't make much difference. This is particularly true of the high resolution smaller sensors (D7xxx/D5xxx/etc)...

 

[Craigus]

It's probably been covered, but to surmise my thoughts on this having read the links posted, I just can't see a practical application where the benefits outweigh the downside of a drastically underexposed image on the rear screen.

It was mentioned above by @KitsuneAndy that he underexposes by up to 1 stop, this is fairly common as far as I know to preserve highlights whether the camera is ISO invariant or not, whereas the discussion in this thread seems to be more about underexposing by a lot to get better IQ.

Landscapes - anything serious and you'll likely be on a tripod at base ISO.
Anything in a studio - lighting is controlled, base ISO.
Weddings/Events - surely you'd want to be able to check that you've captured what you were intending to? Despite the comments previously, sometimes the camera does miss-focus, and we aren't all perfectly able to pre-visualise every shot and nail it every time, call it chimping if you like but I can't imagine there are many photographers who wouldn't check things occasionally on the back screen.
BIF - Covered above, not ideal not being able to check your shot.
There are others of course but most fall into the above areas.

Camera sensors are so good these days anyway at high ISO that I struggle to believe that you'd notice the difference if we are talking about the difference between ISO 800 and 100. You might notice if you print at an enormous size and inspect it with a magnifying glass.

This may be useful if we we're talking about a drastic improvement at the equivalent of say ISO 12,800, but the examples don't show this to me. For real world use I just can't see a benefit.

 

[Fraser Euan White]

Sectionate: the link you read is the one I have posted! Move to the bottom of it to read when it might be used to an advantage
You may have to change the way you Post Process but '''sticking in a rut' is always bad? Surely experimenting with new techniques is fun?

Riddell: Again you are completely missing the point! If photography changes because of a technological advances then it is surely the person who can't/won't change to accept it who is lazy?

Anything that opens photography to more people is excellent news IMO.

 

[sk66]

it is a deliberate step to improve the final photograph.

This really has nothing to do with ISO invariance...
The only concern/benefit is not blowing highlight with amplification (ISO). With an ISO invariant camera it does not matter if the highlights are saved by using ISO 800 (highlight at the right side of histogram) or if saved using ISO 100 (base, highlights middle of histogram). With all other cameras, saving the highlights by using ISO 800 in this scenario would be better.

But saving the highlights using ISO 800 works for all with optimal results. This is basically the ETTR everyone got so involved with/excited about...the only difference is whether I am pushing the brightest parts to the right side of the histogram, or pulling them to keep them w/in the right side.

The other difference is what can be done with the image after the fact. With the ISO invariant camera I can recover the darks up to my ISO noise limit... I.e. my preferred limit on the D810 is ISO 1600. So if I used ISO 800 I can push 1 stop, and if I used ISO 100 I can push 4 stops. Or I could have used ISO 1600 if no highlights would have clipped... the results will be the same (that's the definition of invariant).

And the same is essentially true of the non-invariant camera... if my tolerance is 1600 and I used 800 I can probably push 1 stop with no issue, certainly a half stop. What I can't do is use ISO 100 and push it 4 stops like I can with the other camera. But who cares? The ability to push 4 stops isn't going to generate "better" results... I saved the highlights, that's the only part that mattered at the time of capture.

I use a variety of cameras to include the D810 (invariant) and several others that are not invariant (D5/etc). Learning/developing "bad habits" just because one camera lets me get away with it is a bad idea... it would almost certainly be problematic as I switched between cameras. And it's just lazy... The best images are created when everything is considered/thought out, that includes composition/light/lighting/etc etc, and the resulting camera settings. Just setting the camera to base ISO, f/8, 1/800 for everything "because I can" is just stupid.

 

[sk66]

Perhaps a better way of thinking of it is "how much ability there is to manipulate the image in post before it gets ruined."
I.e. with the non-invariant camera I have to do a better job of getting it right. With the invariant camera I can get away with a little more... but getting it "wrong" and fixing it in post never generates *better results*.

The part everyone gets excited about with the invariant camera is when I *can't* get it right in camera with a single image... the invariant sensor allows me a little more room to save a usable/good image.

 

[riddell]

His argument is that the digital sensor has it's best noise/DR performance at the base ISO so this is the best to use for performance.

I just tried it out very quickly:

Settings on Camera - ISO 100, 1/1160 sec. at f6.3 gave this result:


_DSC3882 by Fraser Euan White on Talk Photography

Quick edit with NO noise reduction applied, exposure corrected by 31/3 stops:


_DSC3882 edited by Fraser Euan White on Talk Photography

(For some reason the gallery wouldn't let me save the edited image as the same size?)

Going back to this post and this example, if you took a shot as under exposed as the example how can you even do a basic thing like verify the image on the back of the screen? I'd barely know what I've shot.

 

[Craigus]

Going back to this post and this example, if you took a shot as under exposed as the example how can you even do a basic thing like verify the image on the back of the screen? I'd barely know what I've shot.

Exactly the point that has been made. In a situation where you aren't already shooting at base ISO, any improvement in IQ gained by doing this is negated by the fact that you can't see the image on the LCD. But that was shot down as "chimping", which appears to make you a bad photographer.

 

[riddell]

Exactly the point that has been made. In a situation where you aren't already shooting at base ISO, any improvement in IQ gained by doing this is negated by the fact that you can't see the image on the LCD. But that was shot down as "chimping", which appears to make you a bad photographer.

Excessive chimping is not the mark of a good photographer, but the screen exists there as a tool and is there to be used. There are many mixed lighting environments a professional will get thrown into, which is a case of quickly balancing everything check your lighting is nice, more of a verification than anything else and then you shoot.

If the exposure is wrong. The exposure is wrong, though people here are trying to argue you can correct that, but what you cannot do is easily correct the balance of lighting afterwards.
That's very different.

In the studio I shoot tethered a lot and often have several people from the art director to client looking at my screen. They want to see a perfectly lit, perfectly colour balanced image, not to mention all the little tiny details, if anything is wrong they want it changed. Are they chimping?

And trust me if everything is not 100% perfect, they'll let you know.

Even at a low key event you'll have people asking to see the back of your camera. How embarrassing is it to show them a practically black image?

 

[dcash29]

Rightly or wrongly I've tried it and find whilst some areas have less noise and are smoother, other areas have less detail.

 

[Fraser Euan White]

Excessive chimping is not the mark of a good photographer, but the screen exists there as a tool and is there to be used. There are many mixed lighting environments a professional will get thrown into, which is a case of quickly balancing everything check your lighting is nice, more of a verification than anything else and then you shoot.


In the studio I shoot tethered a lot and often have several people from the art director to client looking at my screen. They want to see a perfectly lit, perfectly colour balanced image, not to mention all the little tiny details, if anything is wrong they want it changed. Are they chimping?

And trust me if everything is not 100% perfect, they'll let you know.

Even at a low key event you'll have people asking to see the back of your camera. How embarrassing is it to show them a practically black image?

How often in the controlled environment of a Studio do you not shoot at the base ISO of the camera?

 

[Muzzieman]

I’m sorry but this is ridiculous! I run a studio and in a studio environment the aim is to get the perfect exposure in camera. That’s why we use lighting and lighting modification. Yes the base iso is used but not to underexpose and then rectify in post. Photography is capturing light.

 

[Fraser Euan White]

Going back to this post and this example, if you took a shot as under exposed as the example how can you even do a basic thing like verify the image on the back of the screen? I'd barely know what I've shot.

Going back to the days of film when I used a studio alot, the Medium Format camera was loaded with a Polaroid back and exposures were made to check the lighting etc, once you were happy with that you loaded the film back onto the camera and took your 'real' photographs (shooting 'blind').

A modern DSLR has a built in 'Polaroid back' in the LCD screen or if shooting tethered the computer screen. The shot can be set up using what you term as 'the correct exposure' so the results of your lighting can be viewed instantly then to get the very best image quality for the final shot you could lower the ISO (there are very few situations in a studio where I wouldn't be shotting at the base ISO of the camera anyway) and take the image - yes you can't view that image instantly but you can after you edit it.

There is a huge big question over the fact that it doesn't produce better image quality that has been extremely well explained by Steven, but even if it only produces the same image quality I see situations where it would be a good advantage for me.

Personally, the arrival of a true ISO invariant camera that doesn't have any ISO settings the better; it will open up photography to many more people who don't understand exposure or have no desire to learn about it and be a massive step forward for those that do anyway

 

[Fraser Euan White]

I’m sorry but this is ridiculous! I run a studio and in a studio environment the aim is to get the perfect exposure in camera. That’s why we use lighting and lighting modification. Yes the base iso is used but not to underexpose and then rectify in post. Photography is capturing light.

...........but you haven't answered the question - when/how often do you tell people to shoot at ISO 1600 and not ISO 100/200 and why? There is only a couple of situations I can think of. Again - there is no 'Correct' in photography.

Edit:

Sorry Andrew - I notice that you have said the base ISO is used.

Nobody is saying you should under expose at the base ISO. If you have control of the amount of light then the image should be exposed to give the desired results that you are after.

 

[Fraser Euan White]

The other examples are basically wrong... if a camera/sensor is truly ISO invariant (and even many/most that are not), the "ISO noise" characteristics are easily eliminated by selective/global exposure reduction in post... in fact, this characteristic/behavior is so common it leads to the even more problematic ITTR (ISO To The Right) concept.

Steve - hopefully you can answer this and tell me if I am wrong

There are three types of noise - Photon Noise, front end Noise and back end noise?

When you capture an image you have no real control of the first two types of noise and then the analogue amplification happens at which point the ISO you have set is burnt into the file (basically a load of binary numbers)? The back end noise then comes in during the digital conversion of the file so it can be viewed on a computer screen and all the noise added during the analogue conversion is still there but modern sensors have very little back end noise?

Moving the exposure slider in the editing program is just a multiplier for this binary code imported from the camera?

Is my understanding correct?

 

[sk66]

Steve - hopefully you can answer this and tell me if I am wrong

There are three types of noise - Photon Noise, front end Noise and back end noise?

When you capture an image you have no real control of the first two types of noise and then the analogue amplification happens at which point the ISO you have set is burnt into the file (basically a load of binary numbers)? The back end noise then comes in during the digital conversion of the file so it can be viewed on a computer screen and all the noise added during the analogue conversion is still there but modern sensors have very little back end noise?

I think there may be a language issue...There is photon shot noise (a lack of light density at low light levels) which is THE primary contributor to "ISO noise." There is read noise and write noise which are basically the system's noise which the signal (light/photons/generated electrons) must exceed in order to be discernible.
There is both analog and digital amplification that may be applied to the signal before being written (burned in), the specifics of which are camera dependent. And then there is digital amplification in post. Analog amplification has the potential benefit of raising the signal above the noise floor (non-invariant systems). Digital amplification is just a "multiplier," like a brightness setting. That said, digital programs are getting better/smarter every year...

Moving the exposure slider in the editing program is just a multiplier for this binary code imported from the camera?

Is my understanding correct?

At this point in the process, yes.

 

[Devoted Lens]

This whole thread whiffs of 'Why should I get it right in camera, when I can just use Lightroom/Photoshop to get it right for me after the fact'

I'd prefer to spend less time at the computer editting the files, and more time outside taking the photo. This whole method would add a hugely boring step sitting at a desk.

Spot on my friend! This is just yet another example of lazy photography and relying too heavily on RAW as a crutch for bad workmanship (not to say RAW is bad, I exclusively shoot in RAW, but I still work my ass off to get it right 'live', so that editing is minimal).

 

[HoppyUK]

Spot on my friend! This is just yet another example of lazy photography and relying too heavily on RAW as a crutch for bad workmanship (not to say RAW is bad, I exclusively shoot in RAW, but I still work my ass off to get it right 'live', so that editing is minimal).

I can see why you think that, but it isn't - not if you use it sensibly. It'd be very wrong to dismiss ISO-invariance as anything less than a major advance, allowing you to do things that you simply cannot achieve with a conventional sensor, no matter good your craftsmanship (without resorting to HDR technique).

There's no need to change anything about the way you work, no downsides, just shoot as normal. But there will always be the major upside of much more shadow detail to exploit, plus the opportunity to retain very bright highlights just by reducing exposure a little.

 

[Fraser Euan White]

I've now spent countless hours reading up on this matter and the consensus on ISO invariant sensors is as follows:

(1) With a scene in front of the camera photons are emitted from that scene; light areas of the scene emit a higher volume of less random photons than dark areas of the scene which emit a lot less photons and their pattern much more random. It is this 'randomness' that causes photon noise and is why dark areas of an image appear 'more noisy' . This can not be changed and there is nothing the sensor can do about this.

(2) the 'front end noise' or as you call it the read noise is the noise first induced into the system by the sensor and is caused by numerous things some of which are thermal noise from the sensor (dark current) and the ability of the camera to 'reset' the sensor pixels. This noise is induced as photons hit the camera sensors photosites and induce a charge into the camera sensor, one way of reducing 'dark current' noise is to cool the sensor as it heats up with the charge build up, or average the dark current noise over the exposure time and subtract it before the analogue conversion.

(3) All the articles I have read state that it is at this point the Charge from the sensor now goes through an analogue conversion which produces a voltage from the sensor, this voltage is then subject to analogue amplification (gain) which directly depends on the ISO you have set (gain control) ; this information is then 'burn't into the file and can not be changed at a later date. When you set a higher ISO value you are telling the analogue amplifier to add more 'gain' and is the precursor to capturing a 'brighter' image.

(4) In respect to all of the above, sensor design/performance hasn't changed that much over the recent years and noise levels haven't improved drastically up to the point of the analogue conversion/amplification.

(5) Any noise introduced into the system after this point (back end or write) does not go through any analogue amplification which is good.

(6) The last stage of the process is the analogue to digital conversion or back end (write) noise. This conversion takes the voltage produced by the analogue amplification and converts into into a digital format to be displayed (a list of binary numbers containing colour and brightness information from each pixel on the sensor) The more information stored at this point is the Bit depth. This is where there has been major recent advances and the back end (write) noise is now so low that it almost doesn't matter where you move the brightness in the editing software (simulates quite closely the Digital conversion which takes place in the camera) because the noise added at this last stage is so minimal it can 'almost' be neglected. It is this low back end noise that makes the sensor 'ISO invariant', a true ISO invariant sensor has NO noise being added in the analogue to digital conversion.

This then gives us the following workflow:

(Photon induced Noise + Front End or read noise) > Analogue Conversion (Voltage obtained from electron charge CCD) > Analogue Amplification (Induced by ISO set on camera) > (Back end write noise induced by Digital conversion) = Output RAW file.

From the above if a High ISO Value is used (Increased analogue amplification) we are 'multiplying' the following noise induced into the system (Photon induced noise + Front end read noise + Analogue Conversion noise) and this at a later stage can not be effectively lowered in post production, If we originally use a low ISO value then this multiplication in the analogue amplification is lower before we go into the Digital conversion.

In the instance of the Photon noise we know that the randomness of photons emitted from dark objects already causes noise in the dark areas of our images so we would want to keep this multiplication as low as possible at this point to keep the noise in the dark areas of the photograph as low as possible.

With the ISO invariant sensor we can then use the Digital amplification (slider in lightroom) to brighten the lighter areas of the image to selectively edit the exposure of the image; keeping the noise in the shadows as low as possible but 'correct' exposures for our highlights; as the back end/write noise is so low in an ISO invariant sensor the noise produced by doing this is almost negligible. The resultant image will have dark/shadow areas with the minimum noise possible and the highlights will also be exposed correctly with an imperceptible increase in noise in these areas (The Photon noise from brighter areas of the scene is at it's lowest since the 'randomness' is lower.)

Going back to the microphone analogy - if the gain is turned way down and someone speaks quietly into the mic we can hardly hear them, if you turn the gain up (Higher ISO) you can then hear them but everything else (background sounds) is amplified as well. If you could keep the gain on the Mic low ( Low ISO) so that the background was quite but separated out his voice and digitally amplify just that (ISO Invariance) it would be the ideal solution.

 

[Fraser Euan White]

Spot on my friend! This is just yet another example of lazy photography and relying too heavily on RAW as a crutch for bad workmanship (not to say RAW is bad, I exclusively shoot in RAW, but I still work my ass off to get it right 'live', so that editing is minimal).

This type of response I find quite 'tyresome' and is something I have seen over and over again in the 40+ years I have been interested in Photography!

Photographers; professional and keen amateurs are 'snobs' that do not like their 'interest' being made more simple! They take great pride in 'understanding' the exposure triangle, DoF, Shutter speeds etc............whoopy do!

They actually don't want a camera that you can give to any Tom,Dick or Harry and achieve outstanding results from - they want newbies and wannabies to 'learn' their chosen craft just like they had to!

Let me give you a time line since I have been taking photographs:

(1) I was given my first camera by my father - a Canon Rangefinder in 1979 when he purchased a Nikon F2 with a non-metering prism; the photo press at the time 'shunned' the photomic prism stating 'real' photographers didn't need it - they used proper light meters to evaluate the scene and exposure or could guess it from experience!

(2) Nikon introduced the professional Nikon F3; the press at the time and professional photog's 'slagged' it off; bah real photographers don't use an electronically controlled camera with, wait for it...........Aperture priority mode; FFS this camera is for amateurs who don't understand manual exposure! (It went on to become Nikon's longest running Pro Camera but initially had to be sold for less than the older F2)

(3) Autofocus - the press said it was good for the visually challenged photographer but couldn't see any 'mainstream' use for it - surely in photography you had to see well enough to focus a lens; what were camera manufacturers thinking!

(4) Digital: naaaah; film produces much better quality images and digital would never get near the resolution of modern films! To be a PROPER photographer you had to have your own darkroom and process your own images.

So, stop burying your heads in the sand, wake up to advances in camera design and learn about them - otherwise it is you that is Lazy! I n the past we looked on great darkroom printers as a very skilled 'artist' why do we not accept Post Production artists with the same enthusiasm?

Phew............rant over!