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Author Topic: Techniques for getting lower noise, more usable High ISO images?  (Read 24136 times)

Bart_van_der_Wolf

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #20 on: March 19, 2015, 08:45:15 am »

In your D810 doing this is not a bad thing, or at least it is not worse than pushing ISO to achieve higher RAW values. But if any of your friends have Canon cameras, or Nikon cameras with Nikon (not Sony) sensors, underexposing at low ISO is the worst they can do. They'll get better results by pushing ISO for the same exposure (aperture/shutter) because on Canon/Nikon sensors captured DR is improved a lot by pushing ISO (as long as there are no blown highlights of course, which is the case in the underexposure conditions you mention).

However, that benefit for Canon cameras stops approx. around ISO 800 - 1600. Any subsequently higher ISO setting may even reduce (or at least not improve) the Signal to Noise ratio.

Quote
2 shots at the same exposure (aperture/shutter), just changing ISO on a Canon-type sensor:

Yes, but now compare equal exposure at ISO 800 and 12800 ...

Cheers,
Bart
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Rory

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #21 on: March 19, 2015, 10:48:15 am »

What would be a good starting point settings in ACR for a noisy night sport shot?  I have never been able to do a whole lot in ACR to take care of the noise while not totally destroying detail.

Thanks for all the help guys!  Love learning new things.

My experience with ACR/LR noise reduction is to treat the subject and the background separately.  Usually I will deal with the background using the global detail controls.  Obviously less sharpening, more masking and more luminance and color noise reduction reduces noise the most.  You'll have to experiment on your images.  When you have the background where you want it use an adjustment brush to apply negative noise reduction on the subject as necessary.
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dwswager

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #22 on: March 19, 2015, 12:02:53 pm »

In your D810 doing this is not a bad thing, or at least it is not worse than pushing ISO to achieve higher RAW values. But if any of your friends have Canon cameras, or Nikon cameras with Nikon (not Sony) sensors, underexposing at low ISO is the worst they can do. They'll get better results by pushing ISO for the same exposure (aperture/shutter) because on Canon/Nikon sensors captured DR is improved a lot by pushing ISO (as long as there are no blown highlights of course, which is the case in the underexposure conditions you mention).

2 shots at the same exposure (aperture/shutter), just changing ISO on a Canon-type sensor:



Was the 1600 ISO one exposed right and pulled down in post or was the ISO 100 one under exposed and pull up? 

My issue is I'm pretty locked in for shutter speed and aperture.  So the assumpition is I'm shooting 1/640th to stop action and f/2.8 as much light as I can.  Hence the choice is let ISO ride as far as possible OR underexpose by 2-3 stops retarding the ISO rise by those 2-3 stops.  I used to under expose by 1 stop but I think I now have the hang of pulling 2-3stops. 
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dwswager

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #23 on: March 19, 2015, 12:04:24 pm »

My experience with ACR/LR noise reduction is to treat the subject and the background separately.  Usually I will deal with the background using the global detail controls.  Obviously less sharpening, more masking and more luminance and color noise reduction reduces noise the most.  You'll have to experiment on your images.  When you have the background where you want it use an adjustment brush to apply negative noise reduction on the subject as necessary.

Thanks.  That is the type of real world advice that helps.  I actually hadn't thought about negative noise reduction brush adjustments!
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dwswager

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #24 on: March 19, 2015, 12:28:30 pm »

BTW, Here is a sample from a game a couple nights ago so you can see where I'm at.  D810 shot at -1.7EV exposure compensation at ISO 4500 Nikon NEF.  Adjusted in ACR and then downsampled and sharpened in Photoshop.

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Jim Kasson

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #25 on: March 19, 2015, 02:11:09 pm »

BTW, Here is a sample from a game a couple nights ago so you can see where I'm at.  D810 shot at -1.7EV exposure compensation at ISO 4500 Nikon NEF.  Adjusted in ACR and then downsampled and sharpened in Photoshop.



Looks pretty good to me!

bjanes

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #26 on: March 19, 2015, 03:28:33 pm »

Looks pretty good to me!

+1

I agree with Jim, the results look pretty good. Looking at the exif, I see the exposure was -1.67 EV on the camera and +1.75 in ACR and the ISO was 4500 with manual exposure. For my own benefit (and possibly others), I would be interested in how you achieved these results, that is how you metered and set the ISO and arrived at the shutter speed and aperture setting. Presumably as Jim described above?

Thanks,

Bill
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Rory

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #27 on: March 19, 2015, 03:37:22 pm »

BTW, Here is a sample from a game a couple nights ago so you can see where I'm at.  D810 shot at -1.7EV exposure compensation at ISO 4500 Nikon NEF.  Adjusted in ACR and then downsampled and sharpened in Photoshop.



Looks okay to me.  The skin has that noise reduction plastic look.  I think you can improve that with a little selective negative noise reduction if you are using ACR/LR.
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dwswager

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #28 on: March 19, 2015, 03:44:12 pm »

+1

I agree with Jim, the results look pretty good. Looking at the exif, I see the exposure was -1.67 EV on the camera and +1.75 in ACR and the ISO was 4500 with manual exposure. For my own benefit (and possibly others), I would be interested in how you achieved these results, that is how you metered and set the ISO and arrived at the shutter speed and aperture setting. Presumably as Jim described above?

Thanks,

Bill

That's right -1 2/3 stops under.  Was still afraid to go lower.  Will try this weekend.

D810 w/ AF-S Nikkor 70-200mm f/2.8
Auto ISO 64-600
Manual Mode
-1 2/3 stops Exposure Compensation
Center Weighted Metering
Shutter Speed 1/640th (manually set)
Aperture f/3.5 (manually set)
ISO 4500 (Auto, combination of the shutter/aperture and exposure compensation)
Image Area set to 1.2x (25MP)
Auto Focusing
White Balance pre set using an Expodisc (White balance is my hardest problem and just changing the angle gives different results.  I don't have a dual profile for this field which is usually what I do for night games.  I get image in daylight and then at night at a field and use that as the starting profile.)

In ACR, I used the Flat profile as the starting point.

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BJL

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I advise underexposing in low light with the D810 by two or three stops and pushing the raw files in post. In-camera ISOs of over 1000 are achieved partially through digital gain, and you can do digital gain better yourself in post. Then apply nonlinear noise reduction in Lr or ACR, and res the image down to average out noise.
This test was sort of asked before, but I did not really see an answer: given that one is constrained to a certain aperture and shutter speed, I can see setting the "ISO" (in-camera gain setting) a bit below what would given an on-meter exposure in order to protect highlights from amplifier clipping (not photo-site blow-outs), but I am unclear why one would use as much as two or three stops.  Is there evidence of a benefit in going beyond about one stop of under amplification (so-called "underexposure" but actually exposer level is fixed by aperture and shutter speed choice)?  There would need to be some IQ benefit, to offset the less usable in-camera reviews and such.

Also, I understand that in many cameras, increasing EI beyond some level has no effect on the analog gain, and simply sets a flag in the raw file about suggesting a bit shift in raw conversion.  In that case, I would expect that those very high EI setting would not have a problem with blown highlight in the photo-sites themselves, and analog gain would still be leaving the image "dim" in terms of raw levels, so no risk of amplifier clipping either.  Or do some cameras apply bit-shifting "digital amplification" when producing raw files at these high EI settings?  That would seem foolish.

(It would also seem foolish for a camera maker to use huge amounts of analog gain; once analog gain lifts the sensor noise floor clearly above the noise floor downstream from there, digital gain seems both better and cheaper.  Does anyone know the limits of analog gain used in the various Sony/Nikon sensors?)
« Last Edit: March 19, 2015, 03:54:00 pm by BJL »
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Jim Kasson

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Also, I understand that in many cameras, increasing EI beyond some level has no effect on the analog gain, and simply sets a flag in the raw file about suggesting a bit shift in raw conversion.  In that case, I would expect that those very high EI setting would not have a problem with blown highlight in the photo-sites themselves, and analog gain would still be leaving the image "dim" in terms of raw levels, so no risk of amplifier clipping either.  Or do some cameras apply bit-shifting "digital amplification" when producing raw files at these high EI settings?  That would seem foolish.

I am told that some Sigmas work that way. However, in my experience with Sonys (a7 a7S, a7R, a7II, RX-1, NEX7) and Nikons,(D3, D3s, D4, D800E, D810) they actually increase the values in the raw files, and then you can get clipping.

Jim

BJL

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I am told that some Sigmas work that way. However, in my experience with Sonys (a7 a7S, a7R, a7II, RX-1, NEX7) and Nikons,(D3, D3s, D4, D800E, D810) they actually increase the values in the raw files, and then you can get clipping.

Jim
Pity; even my ancient Olympus E-1 did it that way: naive raw convertors that did not know about the flags produced underexposed conversions at EI 3200 and 1600, since the processing to raw was effectively capped at 800 (or was it 1600? It has been a while).

I will try to test my newer Olympus bodies -- unless someone like Guillermo L. has already done so and gives us the answer!
« Last Edit: March 19, 2015, 04:03:28 pm by BJL »
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bjanes

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #32 on: March 19, 2015, 04:32:35 pm »

That's right -1 2/3 stops under.  Was still afraid to go lower.  Will try this weekend.

White Balance pre set using an Expodisc (White balance is my hardest problem and just changing the angle gives different results.  I don't have a dual profile for this field which is usually what I do for night games.  I get image in daylight and then at night at a field and use that as the starting profile.)
In ACR, I used the Flat profile as the starting point.

Thanks for the detailed reply. That's pretty well what I would do. I'ts been awhile since I shot sports under the lights since my son has graduated from high school. I presume the lighting is metal halide without a very high color rendering index. What I did was to take a reading under the lights from a Whibal and use this as a preset for WB. It worked reasonably well. If you have the x-rite ColorChecker Passport, it might be worthwhile to use this to make a custom profile.

Regards,

Bill
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dwswager

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #33 on: April 20, 2015, 07:55:30 pm »

For those that advise under exposure, with the D810 is there a crossover.  I'm trying do figure an overall underexposure versus ISO strategy.

What I mean is at what ISO should I start underexposure?  Is it better to shoot ISO 1600 with 2 stops underexposure or ISO 3200 with 1 stop under or ISO 6400 with 0 under exposure?  What I want to do is build a general set of guidelines on when to let ISO ride and when to use underexposure.
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Jim Kasson

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #34 on: April 20, 2015, 11:21:57 pm »

For those that advise under exposure, with the D810 is there a crossover.  I'm trying do figure an overall underexposure versus ISO strategy.

What I mean is at what ISO should I start underexposure?  Is it better to shoot ISO 1600 with 2 stops underexposure or ISO 3200 with 1 stop under or ISO 6400 with 0 under exposure?  What I want to do is build a general set of guidelines on when to let ISO ride and when to use underexposure.

You might want to take a look at these curves:

http://blog.kasson.com/?p=8230

Read the preceding couple of posts for background.

You can see that the answer to your question depends on which shadow zone is most important to you.

If you care most about the deepest possible shadows, then read noise vs ISO is important to you:

http://blog.kasson.com/?p=6552

Jim
« Last Edit: April 20, 2015, 11:24:50 pm by Jim Kasson »
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dwswager

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #35 on: April 21, 2015, 10:28:25 pm »

You might want to take a look at these curves:

http://blog.kasson.com/?p=8230

Read the preceding couple of posts for background.

You can see that the answer to your question depends on which shadow zone is most important to you.

If you care most about the deepest possible shadows, then read noise vs ISO is important to you:

http://blog.kasson.com/?p=6552

Jim


Thanks.  Not really looking for the deepest shadows, but minimizing noise.
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Jim Kasson

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #36 on: April 22, 2015, 10:01:13 am »

Thanks.  Not really looking for the deepest shadows, but minimizing noise.

Then maybe you should use the mean = 0.04 curve (4 1/2 stops down from full scale). Then the answer to your question is ISO 200. But I don't like to push more than 4 stops in post, because of twists and other usability problems.

Jim

EricV

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #37 on: April 22, 2015, 12:31:16 pm »

From all of these curves and discussion, I see no drawback to letting ISO go as high as warranted by the light level and constrained exposure setting.  There may be no S/N or dynamic range benefit beyond a certain point, but I see no penalty either.  Just hold back enough to avoid highlight clipping.  Am I missing something? 
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Jim Kasson

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #38 on: April 22, 2015, 02:24:07 pm »

From all of these curves and discussion, I see no drawback to letting ISO go as high as warranted by the light level and constrained exposure setting.  There may be no S/N or dynamic range benefit beyond a certain point, but I see no penalty either.  Just hold back enough to avoid highlight clipping.  Am I missing something?  

Not really. You won't get the film-like shoulder of the PV 2012 Exposure control, but you can do that manually.

If you get into the ISO region where the camera applies gain digitally, you'll be able to do it with greater precision (in the computer science sense of the word)  in post.

Jim
« Last Edit: April 22, 2015, 02:27:29 pm by Jim Kasson »
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hjulenissen

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Re: Techniques for getting lower noise, more usable High ISO images?
« Reply #39 on: April 23, 2015, 02:50:11 am »

From all of these curves and discussion, I see no drawback to letting ISO go as high as warranted by the light level and constrained exposure setting.  There may be no S/N or dynamic range benefit beyond a certain point, but I see no penalty either.  Just hold back enough to avoid highlight clipping.  Am I missing something? 
The exposure system of most cameras does not guarantee against highlight clipping afaik. The in-camera histograms and "blinkies" are not robust indicators of raw file clipping. Thus there is some risk of clipping highlights if you increase ISO (either automatically or manually), while there appears to be little to no raw-file IQ benefit beyond some threshold (perhaps ISO 100 for some cameras, perhaps ISO1600 or so for Canon cameras).

Of course, there are operational benefits to using in-camera ISO. You get camera previews and jpegs that make sense. You get raw files that are well aligned with what many raw file developers are optimized for.

-h
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