ISOless sensors, read noise and photography - many questions!

Started 11 months ago | Discussions
Steen Bay
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Re: ISOless sensors, read noise and photography - many questions!
In reply to Steen Bay, 11 months ago

Steen Bay wrote:

bobn2 wrote:

Steen Bay wrote:

bobn2 wrote:

Steen Bay wrote:

bobn2 wrote:

I think personal tests to one's own requirements are always the best - part of getting to know your camera. Just to add, the same goes for you raw processing tools.

The subthread below seems to confirm that. It seems that the ISO on the NEX 5N (and maybe other Sony cameras?) just is a tag in the RAW file. No gain/amplification or digital scaling/multiplication at all. Seems that DxO missed that!

http://www.dpreview.com/forums/post/52263644

The Sony raw coding is unusual, because they use a non-linear 12 bit code (at least in some cameras) - I think we'd want to look closely to convince ourselves that the non-linearity remains the same from ISO to ISO.

Edit: AsIliah's post confirms

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Bob

The 'spikes' in (especially) the shadows (to the left) get wider as the ISO increases, but maybe that has something to do with long exposure NR? (suppose that "2, f/2.8" means 2 seconds, f/2.8)

I wouldn't expect NR to change the histogram on that scale, it would mean hugely visible smudging if that was true. Think, the nature of NR is to change pixels to very nearly the same tone, but within the same distribution of tomes that already exist. If it goes inventing new tones, the results will look very strange indeed.

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Bob

We have many unanswered questions here, but I find it very interesting that the NEX 5N RAW files seem to be able to 'handle' the same exposure without clipping at all (or at least most) ISOs. Seems to me that DxO's Measured ISO therefore also should be the same at all (or most) ISOs.

PS - That should make it possible to shoot 'ISO-less' with the 5N, and still get JPEGs with the 'correct' brightness. Or rather, it'll give you the advantage of 'ISO-less' shooting (more headroom), without actually shooting 'ISO-less'.

P.S. - seems that the histograms Iliah posted didn't confirm D Cox's findings after all..

http://www.dpreview.com/forums/post/52271904

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Reilly Diefenbach
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Re: example of convenient 4-stop "push" acceptable to many
In reply to RussellInCincinnati, 11 months ago

RussellInCincinnati wrote:

Einstein's Ghost: Conversely, I won't be surprised if you used ISO 800 and pushed 4-stop during RAW conversion, that you will notice banding and color issues.

Reilly Diefenbach: Two stops is fine, four or five isn't.

Reilly, in the digital era, why bother expressing an opinion without an example?

Geez, Russell, if we penalized everyone who expressed an opinion without an example, we'd have nobody left in here :^)  I put up way more than my share of examples, not that it does me any good, everyone will keep on doing what they are convinced is correct anyway.

This forum in particular Simon created to be the roped off bastion of those who know a good deal and who have never been wrong about anything, so as you will find out, it's a bit more trouble than it's worth to change anyone's mind with mere actual photographs when the theories, charts and graphs constitute proof of fill in the blank.

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Steen Bay
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Highlight headroom
In reply to boardsy, 11 months ago

boardsy wrote:

It's not obvious (or embarrassing not to have known) that many (most?) high ISO values in many (most?) cameras are not a useful sensor sensitivity gain, but simply a tag in a RAW file to tell the JPG or RAW software where to set brightness, and stretching the actual exposure (aperture & shutter speed) over the available brightness levels, so "high ISO noise" is in fact low exposure noise, exposed (!) by raising brightness levels!! I've only just discovered all this, in a personal Copernican ISO revolution!

Would be ideal if the ISO (on so-called 'ISO-less' cameras with a 'flat' read noise) just was a tag in the RAW file, but it isn't. The 'stretching' is (normally) done before the RAW file is saved on the memory card. If it just was a tag in the RAW file, then it wouldn't be necessary to shoot 'ISO-less' and get dark JPEGs. Then you could just use auto ISO and get JPEGs with the 'correct' brightness, while the RAWs automatically would have e.g. 4 stops more 'headroom' (above metered middle grey) at ISO 1600 than at ISO 100.

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Great Bustard
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BAM!
In reply to Steen Bay, 11 months ago

Steen Bay wrote:

boardsy wrote:

It's not obvious (or embarrassing not to have known) that many (most?) high ISO values in many (most?) cameras are not a useful sensor sensitivity gain, but simply a tag in a RAW file to tell the JPG or RAW software where to set brightness, and stretching the actual exposure (aperture & shutter speed) over the available brightness levels, so "high ISO noise" is in fact low exposure noise, exposed (!) by raising brightness levels!! I've only just discovered all this, in a personal Copernican ISO revolution!

Would be ideal if the ISO (on so-called 'ISO-less' cameras with a 'flat' read noise) just was a tag in the RAW file, but it isn't. The 'stretching' is (normally) done before the RAW file is saved on the memory card. If it just was a tag in the RAW file, then it wouldn't be necessary to shoot 'ISO-less' and get dark JPEGs. Then you could just use auto ISO and get JPEGs with the 'correct' brightness, while the RAWs automatically would have e.g. 4 stops more 'headroom' (above metered middle grey) at ISO 1600 than at ISO 100.

Exactly correct.

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alexisgreat
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Re: astronomical ccd cameras
In reply to Great Bustard, 11 months ago

Is this what astronomical cameras do? I have a Meade DSI II PRO (monochrome camera so no bayer filter array) and it has no ISO setting, you do RAW imaging (it calls it by a different name but there is a free plugin that recognizes the images in Photoshop.)

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RussellInCincinnati
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a little pessimistic to think we're all resisting new ideas
In reply to Reilly Diefenbach, 11 months ago

Reilly: Geez, Russell, if we penalized everyone who expressed an opinion without an example, we'd have nobody left in here :^)

Hey, not thinking of "penalizing". More of a muse on how easy it is to show examples of simple things like whether or not post-processing to high ISO is the same as in-camera raw high ISO, thus encouraging you to post examples when reasonably convenient.

I put up way more than my share of examples, not that it does me any good, everyone will keep on doing what they are convinced is correct anyway.

That's a little pessimistic. Don't you think in a Science and Technology forum that there'd be an unusually high percentage of open, inquisitive and educated minds, compared to say some totally open-topic forum?

For example I would bet here in this forum, you really could indeed entertain people by introducing some technical information that "proves them wrong".

Heck before a week ago I was convinced that, because of a single experiment I did in 2010 with a Nex 5, that there was no way that a Nex C3 could give good results with underexposed-to-ISO-12800 images that were pushed in a raw processor. I bet user "Boardsy" was as surprised and delighted and I was to be shown to be wrong by some posts and info here about noise vs raw ISO settings. 2 pretty ordinary folks right there that would, for example, be impressed by your relevant examples.

This forum in particular Simon created to be the roped off bastion of those who know a good deal and who have never been wrong about anything,

Well I hope that's not true. Would even wager that Eric Fossum for example isn't convinced he's always been "right about everything", even though one of his fingernail clippings knows more about sensor design than I do.

so as you will find out, it's a bit more trouble than it's worth to change anyone's mind with mere actual photographs when the theories, charts and graphs constitute proof of fill in the blank.

Well can't quibble with your prediction, except to say that I knew my ideas about push-processing raw files to be completely wrong, the moment I saw a couple of examples from Boardsy etc through this forum that showed what could be done.

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Jack Hogan
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to EinsteinsGhost, 11 months ago

EinsteinsGhost wrote:

Jack Hogan wrote:

EinsteinsGhost wrote:

Jack Hogan wrote:

EinsteinsGhost wrote:

For most part, yes. Actually, the C3 did a pretty good job at ISO 3200 for that particular image. I do note a slight change in color between ISO 3200 and ISO 800+push, visible in the lower left corner (carpet). The color looks a bit washed out in the latter. And if the rendering is closer in the first, then this case may be a good example where leaving ISO 3200 might be better...

Without knowing whether the alleged color change is due to the sensor or to LR turning on its high-ISO charm it's impossible to determine which ISO produces 'better' IQ.

Jack

Well, let us then discuss EVERY possible combination, and find out the optimal solution, instead of a moving target.

I'd prefer to look at a couple of raws myself.

And that is where my argument came from... looking at images. If you need RAWs, ask the person who posted them.

If only it were that simple we would have had the issue settled months ago. Asking often nets you answers like this or this. And just so that we are clear, this is what we are asking for:

Two D800/e NEFs available for download of a high DR scene, captured with decent technique on a tripod.

  • The first, manually 'properly' exposed at ISO1600;
  • The second captured immediately after at ISO100, all other things being equal.

Anybody?

Jack

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Steen Bay
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to Jack Hogan, 11 months ago

Jack Hogan wrote:

If only it were that simple we would have had the issue settled months ago. Asking often nets you answers like this or this. And just so that we are clear, this is what we are asking for:

Two D800/e NEFs available for download of a high DR scene, captured with decent technique on a tripod.

  • The first, manually 'properly' exposed at ISO1600;
  • The second captured immediately after at ISO100, all other things being equal.

Can't it just be a 'normal' scene/subject with an 'average' contrast? If shooting a high DR scene, then it could be discussed what a 'properly exposed' image is. Is it the exposure the metering suggests, or is it ETTR, while protecting important highlights?

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Elyharbour
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Re: ISOless sensors, read noise and photography - many questions!
In reply to boardsy, 11 months ago

As someone with a science background, but no specific knowledge in the field of electronic imaging, I hesitate to jump in here and ask a question...but here goes.

From what I glean from this and other recent ISO related threads, when I turn up the base ISO value on any camera, beyond a certain point I'm no longer increasing the electronic "gain" "amplification" or whatever it should be called, and further increasing ISO is doing no more than would be achieved by increasing exposure in Lightroom - noise, detail, etc, is going to be approximately the same (forgive my over-simplification, but in essence, that's what I think I'm reading).

If this is the case, then so long as I'm happy with a "dark" photo on the camera screen, I could limit ISO to say 800 or some other value and correct accordingly in PP. But, as this value will vary from camera-to-camera, the only way to find out what it should be, is to try it and compare results. Ie. there is no magic formula we can all apply.

Is this broadly speaking correct?

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Steen Bay
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Re: ISOless sensors, read noise and photography - many questions!
In reply to Elyharbour, 11 months ago

Elyharbour wrote:

As someone with a science background, but no specific knowledge in the field of electronic imaging, I hesitate to jump in here and ask a question...but here goes.

From what I glean from this and other recent ISO related threads, when I turn up the base ISO value on any camera, beyond a certain point I'm no longer increasing the electronic "gain" "amplification" or whatever it should be called, and further increasing ISO is doing no more than would be achieved by increasing exposure in Lightroom - noise, detail, etc, is going to be approximately the same (forgive my over-simplification, but in essence, that's what I think I'm reading).

If this is the case, then so long as I'm happy with a "dark" photo on the camera screen, I could limit ISO to say 800 or some other value and correct accordingly in PP. But, as this value will vary from camera-to-camera, the only way to find out what it should be, is to try it and compare results. Ie. there is no magic formula we can all apply.

Is this broadly speaking correct?

Yes, that's pretty much it. If you shoot at e.g. ISO 800 instead of ISO 3200 (same f-stop/shutter speed), then you'll get 2 stops more of highlight headroom. That's a nice thing of course, but on the other hand, if you didn't blow important highlights at ISO 3200, then you don't really gain anything.

On sensorgen.info you can get an idea about where your camera becomes 'ISO-less' (the ISO at which the read noise is about as low as it gets), but always a good idea to test it yourself.

http://www.sensorgen.info/ (click on a camera to see more data)

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Jack Hogan
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to Steen Bay, 11 months ago

Steen Bay wrote:

Jack Hogan wrote:

If only it were that simple we would have had the issue settled months ago. Asking often nets you answers like this or this. And just so that we are clear, this is what we are asking for:

Two D800/e NEFs available for download of a high DR scene, captured with decent technique on a tripod.

  • The first, manually 'properly' exposed at ISO1600;
  • The second captured immediately after at ISO100, all other things being equal.

Can't it just be a 'normal' scene/subject with an 'average' contrast? If shooting a high DR scene, then it could be discussed what a 'properly exposed' image is. Is it the exposure the metering suggests, or is it ETTR, while protecting important highlights?

Sure, as long as it is reasonably exposed (e.g. not underexposed).  Request also valid for Nex C3 of course, since I got threads mixed up

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Elyharbour
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Re: ISOless sensors, read noise and photography - many questions!
In reply to Steen Bay, 11 months ago

Steen Bay wrote:

Elyharbour wrote:

As someone with a science background, but no specific knowledge in the field of electronic imaging, I hesitate to jump in here and ask a question...but here goes.

From what I glean from this and other recent ISO related threads, when I turn up the base ISO value on any camera, beyond a certain point I'm no longer increasing the electronic "gain" "amplification" or whatever it should be called, and further increasing ISO is doing no more than would be achieved by increasing exposure in Lightroom - noise, detail, etc, is going to be approximately the same (forgive my over-simplification, but in essence, that's what I think I'm reading).

If this is the case, then so long as I'm happy with a "dark" photo on the camera screen, I could limit ISO to say 800 or some other value and correct accordingly in PP. But, as this value will vary from camera-to-camera, the only way to find out what it should be, is to try it and compare results. Ie. there is no magic formula we can all apply.

Is this broadly speaking correct?

Yes, that's pretty much it. If you shoot at e.g. ISO 800 instead of ISO 3200 (same f-stop/shutter speed), then you'll get 2 stops more of highlight headroom. That's a nice thing of course, but on the other hand, if you didn't blow important highlights at ISO 3200, then you don't really gain anything.

On sensorgen.info you can get an idea about where your camera becomes 'ISO-less' (the ISO at which the read noise is about as low as it gets), but always a good idea to test it yourself.

http://www.sensorgen.info/ (click on a camera to see more data)

Thank you. So if I look at the Sony NEX-5 for example (which I do have) the read noise curve shows a minimum at 400 but it looks fairly flat, so, it's not going to make a lot of difference in this case (??) Whereas for the Sony A-55 (similar to my A-57) it slopes down more sharply with a minimum at 1600.

BTW, I expected read noise to slope the other way - ie. lower values at lower ISOs. But that's my lack of understanding showing here...

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panos_m
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Re: ISOless sensors, read noise and photography - many questions!
In reply to Steen Bay, 11 months ago

Steen Bay wrote:

Elyharbour wrote:

As someone with a science background, but no specific knowledge in the field of electronic imaging, I hesitate to jump in here and ask a question...but here goes.

From what I glean from this and other recent ISO related threads, when I turn up the base ISO value on any camera, beyond a certain point I'm no longer increasing the electronic "gain" "amplification" or whatever it should be called, and further increasing ISO is doing no more than would be achieved by increasing exposure in Lightroom - noise, detail, etc, is going to be approximately the same (forgive my over-simplification, but in essence, that's what I think I'm reading).

If this is the case, then so long as I'm happy with a "dark" photo on the camera screen, I could limit ISO to say 800 or some other value and correct accordingly in PP. But, as this value will vary from camera-to-camera, the only way to find out what it should be, is to try it and compare results. Ie. there is no magic formula we can all apply.

Is this broadly speaking correct?

Yes, that's pretty much it. If you shoot at e.g. ISO 800 instead of ISO 3200 (same f-stop/shutter speed), then you'll get 2 stops more of highlight headroom. That's a nice thing of course, but on the other hand, if you didn't blow important highlights at ISO 3200, then you don't really gain anything.

Two gains. Smaller file sizes. No need to meter.

On sensorgen.info you can get an idea about where your camera becomes 'ISO-less' (the ISO at which the read noise is about as low as it gets), but always a good idea to test it yourself.

http://www.sensorgen.info/ (click on a camera to see more data)

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Steen Bay
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Re: ISOless sensors, read noise and photography - many questions!
In reply to panos_m, 11 months ago

panos_m wrote:

Steen Bay wrote:

Elyharbour wrote:

As someone with a science background, but no specific knowledge in the field of electronic imaging, I hesitate to jump in here and ask a question...but here goes.

From what I glean from this and other recent ISO related threads, when I turn up the base ISO value on any camera, beyond a certain point I'm no longer increasing the electronic "gain" "amplification" or whatever it should be called, and further increasing ISO is doing no more than would be achieved by increasing exposure in Lightroom - noise, detail, etc, is going to be approximately the same (forgive my over-simplification, but in essence, that's what I think I'm reading).

If this is the case, then so long as I'm happy with a "dark" photo on the camera screen, I could limit ISO to say 800 or some other value and correct accordingly in PP. But, as this value will vary from camera-to-camera, the only way to find out what it should be, is to try it and compare results. Ie. there is no magic formula we can all apply.

Is this broadly speaking correct?

Yes, that's pretty much it. If you shoot at e.g. ISO 800 instead of ISO 3200 (same f-stop/shutter speed), then you'll get 2 stops more of highlight headroom. That's a nice thing of course, but on the other hand, if you didn't blow important highlights at ISO 3200, then you don't really gain anything.

Two gains. Smaller file sizes. No need to meter.

Right, but if you don't meter and just shoot away at base ISO regardless of the lighting, then you won't really know how much noise you'll get in the final image when increasing the brightness afterwards. The ISO is the cameras noise/exposure meter, so to speak.

On sensorgen.info you can get an idea about where your camera becomes 'ISO-less' (the ISO at which the read noise is about as low as it gets), but always a good idea to test it yourself.

http://www.sensorgen.info/ (click on a camera to see more data)

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Panagiotis

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panos_m
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Re: ISOless sensors, read noise and photography - many questions!
In reply to Steen Bay, 11 months ago

Steen Bay wrote:

panos_m wrote:

Steen Bay wrote:

Elyharbour wrote:

As someone with a science background, but no specific knowledge in the field of electronic imaging, I hesitate to jump in here and ask a question...but here goes.

From what I glean from this and other recent ISO related threads, when I turn up the base ISO value on any camera, beyond a certain point I'm no longer increasing the electronic "gain" "amplification" or whatever it should be called, and further increasing ISO is doing no more than would be achieved by increasing exposure in Lightroom - noise, detail, etc, is going to be approximately the same (forgive my over-simplification, but in essence, that's what I think I'm reading).

If this is the case, then so long as I'm happy with a "dark" photo on the camera screen, I could limit ISO to say 800 or some other value and correct accordingly in PP. But, as this value will vary from camera-to-camera, the only way to find out what it should be, is to try it and compare results. Ie. there is no magic formula we can all apply.

Is this broadly speaking correct?

Yes, that's pretty much it. If you shoot at e.g. ISO 800 instead of ISO 3200 (same f-stop/shutter speed), then you'll get 2 stops more of highlight headroom. That's a nice thing of course, but on the other hand, if you didn't blow important highlights at ISO 3200, then you don't really gain anything.

Two gains. Smaller file sizes. No need to meter.

Right, but if you don't meter and just shoot away at base ISO regardless of the lighting, then you won't really know how much noise you'll get in the final image when increasing the brightness afterwards. The ISO is the cameras noise/exposure meter, so to speak.

I understand what you say but if you choose the minimum shutter speed you can handhold then you will get the minimum amount of noise for the particular circumstance. Why the need to know the noise amount in advance?

An example from sometime ago. At a stage shooting I set up the D3 like this:

http://www.dpreview.com/forums/post/50464260

On sensorgen.info you can get an idea about where your camera becomes 'ISO-less' (the ISO at which the read noise is about as low as it gets), but always a good idea to test it yourself.

http://www.sensorgen.info/ (click on a camera to see more data)

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Iliah Borg
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Re: ISOless sensors, read noise and photography - many questions!
In reply to Steen Bay, 11 months ago

if you don't meter and just shoot away at base ISO regardless of the lighting, then you won't really know how much noise you'll get in the final image when increasing the brightness afterwards.

If exposure the maximum possible exposure is used the image is as low noise as it can be? But I still do do use a handheld meter to know how much I'm underexposing for the midtone-to-be.

The ISO is the cameras noise/exposure meter, so to speak.

The amount of underexposure at maximum ISO before the point where raising ISO further stops decreasing noise in shadows is my indicator.

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wchutt
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Think About Maximizing Signal During Exposure
In reply to boardsy, 11 months ago

" if the sensor is effectively ISOless then is base ISO always optimal (providing that you can see enough of the image on your camera to compose and focus in a sub-optimal exposure scenario), or are you as well off raising it in camera (providing highlights are preserved) rather than in RAW/pp?"

The answer is depends on the camera design. Some Canons perform better with ISO amplification because their analog-to-digital converter hardware works better with post-acquistion, in-camera amplification. The Leica M8 and M9s are essentially ISO-less until ISO 800 where the signal-to-noise ratio (and dynamic range) degrades significantly.

"- is it possible or likely that the camera's ISO implementation is better tuned to its sensor and RAW data than your RAW software? Aside from highlight preservation on exposure, are there other benefits to "doing ISO" in post?"

See above. Highlight preservation is not an issue if you maximize exposure (see below) at base ISO. The only benefit to using base ISO and increasing brightness in post has to do with maximizing the signal recorded by the sensor. Do not just think of noise. Instead think about the signal to noise ratio. The electronic noise of the sensor (read noise) is independent of ISO. When ISO is increased to one stop above base ISO, one stop less signal is recorded by the sensor when the shutter is open. At least this is what the light meter tells you to do. The SNR and dynamic range decreases by one stop. After the shutter closes the signal and the noise is amplified so the ADC operates at it's maximum performance level.The role of increasing ISO is to increase the light meter response so you can use a shorter shutter time or smaller aperture and still make the most of the analog to digital converter. Above base ISO less signal is recorded when the shutter is open because that's what the light meter tells you to do.

"- for a given sensor may it be more effective to raise ISO to some minimum/optimal level vis-a-vis its read noise?"

No. Some sensors will benefit (see above) and others will suffer. The only thing a photographer can do is maximize exposure of the sensor when the shutter is open.

How to maximize exposure

  • Set ISO to base ISO (unless your camera is one of the few that have better SNR above base ISO).
  • Choose the shutter time and aperture to maximize exposure while retaining any highlights important to the photograph you envision in your mind. This means you might intentionally overexpose unimportant highlights such as interior lights, car headlights, street lights etc., but you would not overexpose a blue sky. If all the highlights must be properly exposed to make the photograph, then the shadow SNR will suffer. In this case minimizing ISO is even more important because you need all the DR your sensor can deliver.
  • If the shutter speed is too long or the aperture is too narrow to record the photograph you envision, increase ISO by the smallest amount required to us appropriate exposure parameters.

Maximizing exposure at the base ISO, or the appropriate practical ISO above base ISO, insures you have the best shadow SNR and the best overall dynamic range.

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RussellInCincinnati
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on third thought, for Nex C3 raw, this topic not important
In reply to boardsy, 11 months ago

Summary: Am saying more narrowly that doing anything but maximizing your exposure, specifically via using the slowest shutter speed and thus lowest ISO that's practical and doesn't overexpose, for the aperture and scene you've chosen, for almost all practical purposes will not give you any higher-quality raw files, and thus is not worth troubling oneself over--regardless of whether or not a Nex C3 is "ISO-less" or whatever.

========

Boring Details

Boardsy, after a couple of days of Nex C3 testing, have concluded that, for C3 raw users, this topic of ISO-less-or-not has no practical value. Because there's nothing wrong with the way the Nex C3 handles the raw data when you set the ISO above 800. I.e. since there's no problematic increase in read noise at ISOs above 800, there's no reason to stay away from those settings.

Wchutt, in this thread, sums up my own advice:

Maximizing exposure at the base ISO, or the...[least]...practical ISO above base ISO, insures you have the best shadow SNR and the best overall dynamic range.

The common-sense idea that the sensor works best when it has as much light to work with as you can get to it (but of course not so much that at your chosen ISO there are important pixels that are real close to the right-hand edge of your C3 exposure histogram), is always true. And you may note that the above run-on sentence makes no mention of whether or not the camera is "ISO-less."

Am not saying that it's uninteresting or dumb or boring to know whether or not a Nex C3 writes different values into it's raw files at various ISO settings for the same manual exposure(which it does, easy to see thanks to Iliah Borg's nice RawDigger program). And I appreciate this thread topic for its educational aspects, for the (in some ways impractical pleasure of) people who just enjoy understanding camera sensor technology and raw file structures.

But am claiming (along with what wchutt implies) that there's nothing practical to be gained by thinking about this topic for a Nex C3 (i.e. whether or not the C3 changes the raw values or doesn't at various ISOs), if you already have the religion of always exposing as much as practical. (Again expose as much as you can without running any important pixels super close to the right-hand edge of your exposure histogram.)

This contradicts my writing yesterday, extolling the virtues of not setting the Nex at ISO 800 no matter how dim the light. While it's true (and interesting to me) that you can limit a Nex C3 to ISO 800 without loss of image quality, no matter how much the scene looks dim because of your too-low ISO setting, my further testing of both too-low and too-high ISO scenes points unmistakeably to there being no point to worrying about your ISO setting in dim light. Because just setting the ISO in dim light to whatever number above 800 lets the scene preview look good is fine--since again there is no read noise penalty for above-800 ISOs.

We might as well just enjoy the nice preview and playback afforded by simply:

selecting whatever lowest ISO lets us capture the scene with the brightest important pixels being just shy of the right-hand edge of the exposure histogram.

Or of course, if the scene is high-key with lots of important highlight detail that you want perfectly rendered, back off exposure so that the brightest pixels in the exposure histogram are maybe 80% of the way to the right. I (and probably you) back off exposure when trying to, say, capture every possible detail in a boring photo of puffy clouds...or more practically, stand off a little farther from the right-hand edge of the histogram when a model is wearing white anything.

By the way, am not saying there are no theoretical differences in what you can get out of a Nex C3 with various too-low raw file ISO settings. But for noticeable purposes am sticking by the statement at the top of this message.

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boardsy
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full circle: "just raise ISO, when necessary!"
In reply to RussellInCincinnati, 11 months ago

RussellInCincinnati wrote:

Summary: Am saying more narrowly that doing anything but maximizing your exposure, specifically via using the slowest shutter speed and thus lowest ISO that's practical and doesn't overexpose, for the aperture and scene you've chosen, for almost all practical purposes will not give you any higher-quality raw files, and thus is not worth troubling oneself over--regardless of whether or not a Nex C3 is "ISO-less" or whatever.

========

Boring Details

Edited highlights:

We might as well just enjoy the nice preview and playback afforded by simply:

selecting whatever lowest ISO lets us capture the scene with the brightest important pixels being just shy of the right-hand edge of the exposure histogram.

Or of course, if the scene is high-key with lots of important highlight detail that you want perfectly rendered, back off exposure so that the brightest pixels in the exposure histogram are maybe 80% of the way to the right. I (and probably you) back off exposure when trying to, say, capture every possible detail in a boring photo of puffy clouds...or more practically, stand off a little farther from the right-hand edge of the histogram when a model is wearing white anything.

By the way, am not saying there are no theoretical differences in what you can get out of a Nex C3 with various too-low raw file ISO settings. But for noticeable purposes am sticking by the statement at the top of this message.

Not boring at all; a very interesting line of thought and exploration - thanks Russell! And it seems conclusive for this sensor:

From http://www.sensorgen.info/SonyNEX-C3.html

- no visible benefit in keeping ISO at the low read noise minimum (800 for this sensor), and possibly struggling with a dim view/LCD in camera, and raising brightness later.

I'd be very interested if bobn2, Great Bustard, Gollywop, Detail Man et al would agree?

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Regards,
Alan
my Flickr

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bobn2
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Re: full circle: "just raise ISO, when necessary!"
In reply to boardsy, 11 months ago

boardsy wrote:

From http://www.sensorgen.info/SonyNEX-C3.html

- no visible benefit in keeping ISO at the low read noise minimum (800 for this sensor), and possibly struggling with a dim view/LCD in camera, and raising brightness later.

I'd be very interested if bobn2, Great Bustard, Gollywop, Detail Man et al would agree?

It depends on the scene. If the scene has a higher tonal range than can be handled by the 'correct' ISO, then there is advantage to using the lower ISO.

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Bob

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