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Thread: Noise level at base ISO pushed vs. higher ISO

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    Noise level at base ISO pushed vs. higher ISO

    I'm confused… but that's not necessarily a bad thing here :-)

    I always thought an increase in ISO results in the same noise level as an underexposed capture pushed by the respective value.
    So ISO50 underexposed by one stop and pushed in post by 1 EV is literally the same as shooting at ISO100.

    Back in the days I did that test with my P45 and the results were as they were supposed to be.
    Yesterday I did that test again. And as I was so perplexed about the results I did it again today under different conditions.

    The underexposed shots at base ISO but pushed in Capture One by the respective values look much better than shooting at higher ISO.

    The only explanation I can think of is shadow recovery and noise handling in Capture One has very much improved (my former test was done in C1 3.7 something).
    Or has anyone a better idea about that? Has anyone discovered the same?

    Here are the comparisons (same settings for all captures, no sharpening, noise reduction for luminance and color as written on the crops).
    The difference at ISO50+1/ISO100 is not so obvious (in some areas of the capture it is) but at ISO200 it's a big difference.
    Not only noise - all tonal transitions in the pushed base ISO shot look much better.
    I ran that test with my P21+ as well - with the same results (at ISO100+1*/ISO200 even more obvious as with the P45).

    *ISO100 is base ISO on the P21+
    Last edited by thomas; 2nd February 2010 at 15:58.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Thomas 5.0 the major improvement not talked about really in public but as a beta tester was the noise levels . They have been greatly improved along with the sharpening routines so not surprised to see that you are seeing these results. BTW I have the latest beta 5.1 and even more improvements and functions, should be out very soon too. Good news is they keep building a better bread box, I like that to be honest.
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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Guy Mancuso View Post
    Thomas 5.0 the major improvement not talked about really in public but as a beta tester was the noise levels . They have been greatly improved along with the sharpening routines so not surprised to see that you are seeing these results. BTW I have the latest beta 5.1 and even more improvements and functions, should be out very soon too. Good news is they keep building a better bread box, I like that to be honest.
    Guy, thanks!
    The images shown were processed through 5.1 Beta2. However I did not apply (user adjustable) noise reduction for luminance (nor the long exposure or surface setting or anything). My reading is that they improved the way NR works (and indeed works like charm!)... but if I do not apply NR (Lum.)... it must be a sophisticated way to recovery shadows.
    Unless I am not mistaken... from now I always shoot at base ISO

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    Re: Noise level at base ISO pushed vs. higher ISO

    I have not played much with the new beta version and maybe I should try those Sensor plus shots again and see what's up
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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Guy Mancuso View Post
    I have not played much with the new beta version and maybe I should try those Sensor plus shots again and see what's up
    maybe you should skip binning and shoot everything at base ISO
    No... yes, it would be nice if could have a look at it. I think the newer backs have some stops "real" ISO (am not quite) sure... but the P45 (non plus) definitely not.
    I thought the P21+ might have "real" ISOs... but from my findings it's probably just gained base ISO... in any case also with the the P21+ the pushed base ISO shots look better than setting the back to higher ISO (on the other hand the P21+ has really "nice" noise... still).

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    Re: Noise level at base ISO pushed vs. higher ISO

    I'm going to try some full res ISO 800 which I have been meaning to do anyway. Just need to get past the next couple days and I can concentrate on photography than. Lot's of stuff going on this week
    Photography is all about experimentation and without it you will never learn art.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Guy Mancuso View Post
    I'm going to try some full res ISO 800 which I have been meaning to do anyway. Just need to get past the next couple days and I can concentrate on photography than. Lot's of stuff going on this week
    take your time - that's fine!

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    Re: Noise level at base ISO pushed vs. higher ISO

    What were your Noise Reduction Advanced settings (5.1 feature)?

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    Re: Noise level at base ISO pushed vs. higher ISO

    Also what happens if you adjust color noise reduction settings to zero as well? The aggressiveness of those float as ISO changes as well and at higher settings can result in what feels like luminance noise reduction.

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    Re: Noise level at base ISO pushed vs. higher ISO

    as I said...:

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by dougpetersonci View Post
    Also what happens if you adjust color noise reduction settings to zero as well? The aggressiveness of those float as ISO changes as well and at higher settings can result in what feels like luminance noise reduction.
    however it would apply to both the captures as I set the same Col.NR for both of the respective shots.
    The values 12, 25, 45 for Col.NR are my settings for my P45's ISOs 50, 100, 200. And the truth is that I could even reduce Col.NR for the pushed shots - but not for the regular shots.

    edit:
    left pushed +2EV, right ISO200; col.NR zero
    Last edited by thomas; 2nd February 2010 at 16:40.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Thomas, thanks for this experimentation. Very valuable. I use C1 V5, and will try the 800 ISO vs. your suggestion this weekend.
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    Re: Noise level at base ISO pushed vs. higher ISO

    I will try that and see, i did shoot at ISO 100 and pushed it by 2 stops and it was fine, but i didn't shoot at ISO 400 to compare.

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    Re: Noise level at base ISO pushed vs. higher ISO

    I've been doing this very thing for a few years since I discovered it was a very significant difference in M8 files --- ISO 640 pushed 2 was vastly superior to in cam 2500. It worked on my P45+ as well, saving a good 1/2 stop on noise at 400 and 800, however it seems to be a Kodak sensor trait as it doesn't appear to make much difference with my P65+ files.
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    Re: Noise level at base ISO pushed vs. higher ISO

    @ s.agar +Professional - I am looking forward to your findings - thanks a lot!

    @ Jack - I'm glad you came to the same results!
    Basically I can't imagine that the software goes beyond physical limits. So it could also be possible that my back produces too much noise at higher ISO settings.
    But what I've seen from other P45s my copy seems to be rather good. Not only the ISO50 is superb, also ISO100 is quite good (keep in mind it's 2005 CCD technology). Too, my P21+ does exactly the same: pushed base ISO is better than shooting higher ISO. And as you found the same results I don't think it's a particularity of my P45 sensor.
    As to your P65+ - maybe it's beacause the P65+ has "real" ISO?

    BTW: I was interessted in this ISO thing because when you apply LCC based light falloff in Capture One you are pushing ISO at the edges (of course). Now there were some images in which the increase of light seemed to increase noise just a little bit, literally invisible, whilst in other examples the ISO push at the edges was more obvious. I couldn't draw any final conclusion from that and started to play around with this thing...

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    Re: Noise level at base ISO pushed vs. higher ISO

    Just to be sure, do you push the exposure level for more stops for ISO? I mean if i shoot at ISO 100 and i move the exposure to +1 then it is like i push the ISO up to 200? or there is another way to push up the ISO?

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Professional View Post
    Just to be sure, do you push the exposure level for more stops for ISO? I mean if i shoot at ISO 100 and i move the exposure to +1 then it is like i push the ISO up to 200? or there is another way to push up the ISO?
    this way:
    - shoot at ISO50 for a correct exposure, say, f8 + 1/30''
    - shoot at ISO50 and underexpose 1 stop, i.e. at f8 + 1/60''
    - shoot at ISO50 and underexpose 2 stops, i.e. at f8 + 1/125''
    - shoot at f8 + 1/60'' and set the back to ISO100 (for correct exposure)
    - shoot at f8 + 1/125'' and set the back to ISO200 (for correct exposure)


    for the comparision:

    - push the 1 stop underexposed ISO50 shot by 1 stop in the RAW software and compare it to the ISO100 shot
    - push the 2 stops underexposed ISO50 shot by 2 stops in the RAW software and compare it to the ISO200 shot

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by thomas View Post
    this way:
    - shoot at ISO50 for a correct exposure, say, f8 + 1/30''
    - shoot at ISO50 and underexpose 1 stop, i.e. at f8 + 1/60''
    - shoot at ISO50 and underexpose 2 stops, i.e. at f8 + 1/125''
    - shoot at f8 + 1/60'' and set the back to ISO100 (for correct exposure)
    - shoot at f8 + 1/125'' and set the back to ISO200 (for correct exposure)


    for the comparision:

    - push the 1 stop underexposed ISO50 shot by 1 stop in the RAW software and compare it to the ISO100 shot
    - push the 2 stops underexposed ISO50 shot by 2 stops in the RAW software and compare it to the ISO200 shot
    Ah cool, i will do that ASAP.

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    Re: Noise level at base ISO pushed vs. higher ISO

    What do you mean by "pushing" during PP? Generally, reducing exposure and increasing gamma often looks better. It shoulders the highlights, which is highly noticeable, and pays for it in the shadows, which may not be as noticeable. NR can be selectively applied to the bottom end, without really affecting the overall image appearance much. Depends on where you're going and the look you're after. IMO.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Jan,

    to push we use the "exposure" slider in RAW not the "Brightness" slider or Curves. The main difference is the exposure slider affects the entire image linearly across the histo, where the Brightness protects the end points.
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    Re: Noise level at base ISO pushed vs. higher ISO

    Hmm, I think the C1 exposure slider stretches the histogram, clipping the top end - right? This is a little different from using a curves panel and raising the middle of the curve, or a little below middle (maybe 1/3 up the scale). The former is useful when the high end of the histogram is empty and the image is bunched up at the lower end. The latter when most of the image is bunched up at the lower end but it's still desirable to retain what's at the high end (and what would normally have been clipped with more exposure).

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Jan Brittenson View Post
    Hmm, I think the C1 exposure slider stretches the histogram, clipping the top end - right? This is a little different from using a curves panel and raising the middle of the curve
    for this topic a curve is not appropriate. We are talking about a file being 2 stops underexposed. So you have to recover 2 stops in the shadows (actually 2 stops in the entire image) - you can't recover shadows by raising the middle of the curve.
    Too, this was not about "what's the best way to recover an underexposed image". It was simply about the comparison of hardware based ISO-push (digiback) vs. software ISO-push.
    Too, a capture underexposed by 1 stop but pushed with "exposure" in the software and a capture taken with 1 stop higher ISO look the same (literally), i.e. the dispersion of luminance over the tonal range is the same (the same goes for 2 stops and 2.5 stops).
    Okay, the image with the higher ISO may show little less DR (maybe around 0.1EV or so)... but that's just a little difference and not relevant here.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Sorry i didn't do any test yet because i was lazy, tired and a bit busy, but last question, can i use artificial lights [studio strobes, speedlights,...] for this test or i should keep natural light available [room light, outdoor, windows,...]?

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    Re: Noise level at base ISO pushed vs. higher ISO

    Tungsten is the worst source for noise. I always use tungsten light when testing for noise.
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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Guy Mancuso View Post
    Tungsten is the worst source for noise. I always use tungsten light when testing for noise.
    I agree it is the worst light for noise, ok then, i will use normal tungsten room light for the test even we have florescent as well], so in this case i should use tungsten WB.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Professional View Post
    can i use artificial lights [studio strobes, speedlights,...] for this test or i should keep natural light available?
    eihter way. It's not about the noise level. It's only about the relation of base ISO pushed and shotting at the respective ISO setting.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Hi People, i did the test but there is something wrong with the results, so that i don't know if i did the test correct or not.

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    Re: Noise level at base ISO pushed vs. higher ISO

    ISO 50


    ISO 50 with +1 exposure


    ISO 50 with +2 exposure


    ISO 100


    ISO 200

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Professional View Post
    Hi People, i did the test but there is something wrong with the results, so that i don't know if i did the test correct or not.
    The shots are fine. Now you have to push the 1 stop underexposed ISO50 shot in the RAW software by 1 stop and the 2 stops underexposued ISO50 by 2 stops.... so taht all the catpure have (about) the same luminance level.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by thomas View Post
    The shots are fine. Now you have to push the 1 stop underexposed ISO50 shot in the RAW software by 1 stop and the 2 stops underexposued ISO50 by 2 stops.... so taht all the catpure have (about) the same luminance level.
    Sorry that i didn't clarify my post above, in fact #2 and #3 posted above are pushed already as written in the ACR [#2 with +1 or 1 stop pushed in exposure, #3 is pushed with +2 exposure, is +1 in exposure means 1 stop?]

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by thomas View Post
    you can't recover shadows by raising the middle of the curve.
    Of course you can. Raise any point on the curve and you increase contrast below that point while decreasing above it. Increasing contrast brings out detail, hence raising any point on a curve increases shadow detail by virtue of increased contrast.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by Jan Brittenson View Post
    Of course you can. Raise any point on the curve and you increase contrast below that point while decreasing above it. Increasing contrast brings out detail, hence raising any point on a curve increases shadow detail by virtue of increased contrast.
    basically you are right.
    But for the comparision of a pushed underexposed shot and a shot at the respective higher ISO setting "exposure" to +1 (resp. +2) preserves the dispersion of luminance of both the captures. Due to the "magnetic" (?) design of the curves in C1 you'll have to make multiple points in the curve (and one of them has to be at the very low end of the curve) so I think you'll have a hard time to recover the same dispersion of light all over the histogram. With "exposure" it's one click here.

    @Professional: why don't you take the Hasselblad software? I don't think ACR will do it here.
    The 1 stop underexposed ISO50 shot pushed by the exposure value "1" should look like the ISO100 shot and the 2 stops underexposed ISO50 shot pushed by the EV "2" should look like the ISO200 shot.
    If not that's probably a software issue.

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    Re: Noise level at base ISO pushed vs. higher ISO

    Quote Originally Posted by thomas View Post
    basically you are right.
    But for the comparision of a pushed underexposed shot and a shot at the respective higher ISO setting "exposure" to +1 (resp. +2) preserves the dispersion of luminance of both the captures. Due to the "magnetic" (?) design of the curves in C1 you'll have to make multiple points in the curve (and one of them has to be at the very low end of the curve) so I think you'll have a hard time to recover the same dispersion of light all over the histogram. With "exposure" it's one click here.

    @Professional: why don't you take the Hasselblad software? I don't think ACR will do it here.
    The 1 stop underexposed ISO50 shot pushed by the exposure value "1" should look like the ISO100 shot and the 2 stops underexposed ISO50 shot pushed by the EV "2" should look like the ISO200 shot.
    If not that's probably a software issue.
    I will check the files again and try the Hasselblad software if i will see a difference, i tried also to push the exposure from Photoshop after open not by ACR and still same problem, so is Photoshop also not reliable software as well, why will that Hasselblad software will do better job in exposure here?!!!

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    Re: Noise level at base ISO pushed vs. higher ISO

    You have to push exposure in the raw processor -- I would use Hassy's proprietary software, not ACR/LR since they treat "exposure" differently depending on manufacturer...
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