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In praise of 1600 ISO


chris_tribble

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However I don´t understand the "set WB to 3200K" theory. When I use my M9 at night in cities and use auto WB I often get too yellowish images, right. But this is very easy to adjust with the WB selector in Lightroom, and the problem is solved. Or do I miss something here - would it be better to have started with 3200K instead? I use dng of course.

Thanks for comments...

/Anders

 

My experience - and Thorsten's - is that presetting a specific kelvin value reduces the amount of work that you have to do in post. I was working with 2500 for stage lighting - Thorsten recommends 3200 for night time street / mixed light. This produces much more consistent results than AWB.

Chris I wonder why you did not set manual WB when you had the chance during the dress rehearsal. WD

Light temperatures were wildly all over the place - setting a single manual WB and having to reset would have been completely unrealistic. If I was doing a studio shot of cars, then your approach would be absolutely the way to go. I wouldn't work that way in stage / performance work.

 

Thanks for various comments - glad the thread's of interest.

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sblitz

 

Noise and white balance.

 

If you realize that the sensor is a 160 ISO sensor that can only "see" better when helped by artificial algorithms, you will see why you get more noise the more you push the lack of ability to actually see.

 

For each step in ISO you double the amount of light the sensor must be able to see despite is can only see 160 ISO.

 

320 ISO, 640 ISO, 1250 ISO, 2500 ISO - each step is doubling the light. Hence at 2500 ISO you pretend the sensor sees 16 times better than it actually does. And to the degree algorithms in software can remedy that, you don't have noise.

 

So that is the one dimension. If you have 8x og 16x the sensors ability to see, and then at the same time want to adjust the quality in color temperature or exposure. Then you are really pushing things to the limit with current technology. And whenever you push the image quality to places where there is no real data in terms of light to work on, or algorithms that can figure out how it should look, you get noise.

 

So noise is simply "no data" where the sensor/software will fill out the gaps with blue dots, black dots or any random data to make it look like something.

 

(This, by the way, is also why you have almost no noise when using 800 ISO in daylight: Because there is light and thus data to the sensor. But in the dark there is none, and that is usually where you need the fish ISO).

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Can someone knowledgeable fill me in on why, when I set a custom white balance using a grey card, no camera (but here the M9) can tell me what that value is in Kelvin?

 

I would love that, it would give me a working knowledge of the WB in K. Is it because camera and post K differ somehow, as I skimmed in Thorsten's article?

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Tried it tonight walking home. You are absolutely correct. Thanks!

Hooray :)

 

Can someone knowledgeable fill me in on why, when I set a custom white balance using a grey card, no camera (but here the M9) can tell me what that value is in Kelvin?

 

I would love that, it would give me a working knowledge of the WB in K. Is it because camera and post K differ somehow, as I skimmed in Thorsten's article?

Afraid I can't help here.

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Can someone knowledgeable fill me in on why, when I set a custom white balance using a grey card, no camera (but here the M9) can tell me what that value is in Kelvin?

 

I might be misunderstanding your question but doesn't it tell you the Kelvin value in the exif data?

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.....

Light temperatures were wildly all over the place - setting a single manual WB and having to reset would have been completely unrealistic.... .

Chris, not wishing to labour this point but I was not suggesting that you continuously measure and reset your manual WB. I was merely advocating using a typical actually measured manual setting rather than picking a Kelvin value in the manner you described. Given the time, such as prior to a rehearsal or even during a rehearsal, that becomes your datum WB for the duration of the shoot. We are saying the same thing but my datum is actually measured on location rather than using a theoretical unmeasured value.

 

Whatever, it is the results which count and in theatre work there is scope for permitting theatrical lighting effects. :)

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David - I see your point. I suppose my strategy is to take a couple of WhiBal shots as a reference. I can use these in post as starting poijnts if things go awry. My experience this time was that the fixed (2500 or 3200) Kelvin worked brilliantly. I needed NO WB adjustment on shots like these. Each one rendered in a way that reflected the reality. This is no reflection on your approach, but it does seem to indicate something that does work pretty well.

 

Best

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Manual white balance values can be found in Photoshop (I have CS5) under file info/advanced

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This thread inspired me to try iso 1600 just now, for the first time..oh dear!

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... I needed NO WB adjustment on shots like these. Each one rendered in a way that reflected the reality....

Best

 

Chris, this is interesting, what you say. (And I want to emphasize that if I understand you right, then I agree with you, I am not arguing). Meaning it is important to reflect the light of reality. Because what I see from your last 2 pictures is that WB is completely "wrong"! Look at the hands of the operator or the face of the actress. Both should be tweaked in PP. But the question is, how is the light at the location presented, not what is the correct WB. In a way, the correct WB discussion is as pointless as what is the correct exposure or correct aperture setting.

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I don't know... With hot pixel I think we should have a vertical line. In any case there is a problem....

Check the camera with a different card. Makes sure the contacts are clean - I don't think it's hot pixel or red stripe.

Best of luck!

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Chris, this is interesting, what you say. (And I want to emphasize that if I understand you right, then I agree with you, I am not arguing). Meaning it is important to reflect the light of reality. Because what I see from your last 2 pictures is that WB is completely "wrong"! Look at the hands of the operator or the face of the actress. Both should be tweaked in PP. But the question is, how is the light at the location presented, not what is the correct WB. In a way, the correct WB discussion is as pointless as what is the correct exposure or correct aperture setting.

 

Couldn't agree more - with stage lighting that has blue and red gels + neon strip thrown in for good measure + a few LED lights, what's correct? The critical thing for me is a rendering that gives an honest account of how things looked at the time. These are how they were... Tweaking would be possible (one click with the WB tool on the white fabric), but it would have destroyed the warm colour values of the scene - and introduced other problems! See below:

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sblitz

 

Noise and white balance.

 

If you realize that the sensor is a 160 ISO sensor that can only "see" better when helped by artificial algorithms, you will see why you get more noise the more you push the lack of ability to actually see.

 

So that is the one dimension. If you have 8x og 16x the sensors ability to see, and then at the same time want to adjust the quality in color temperature or exposure. Then you are really pushing things to the limit with current technology. And whenever you push the image quality to places where there is no real data in terms of light to work on, or algorithms that can figure out how it should look, you get noise.

 

So noise is simply "no data" where the sensor/software will fill out the gaps with blue dots, black dots or any random data to make it look like something.

 

(This, by the way, is also why you have almost no noise when using 800 ISO in daylight: Because there is light and thus data to the sensor. But in the dark there is none, and that is usually where you need the fish ISO).

 

Noise and white balance have no correlation whatsoever assuming you shoot raw. You are partially correct with the rest of your post (higher ISO isn't an algorithm, it's a multiplier, just try pushing an ISO 160 exposure 4 stops and you'll cry to have ISO 2500 back).

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Noise and white balance have no correlation whatsoever assuming you shoot raw. You are partially correct with the rest of your post (higher ISO isn't an algorithm, it's a multiplier, just try pushing an ISO 160 exposure 4 stops and you'll cry to have ISO 2500 back).

 

I'm no expert but a year back or so very experienced canon 5DII people compared ISO100 underexposed pushed in post to "correct" ISO shots and the conclusion was that correct exposure was better every time. Not sure the reason why, and this is going a bit OT.

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