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Author Topic: ISO 640 has less noise than ISO 100....WT@#?  (Read 14987 times)

texshooter

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ISO 640 has less noise than ISO 100....WT@#?
« on: June 17, 2012, 03:09:05 am »

i just saw a noise/iso comparison chart for the 5D MarkIi that shows ISO 640 having less noise than ISO 100.  Is this a joke?
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Guillermo Luijk

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #1 on: June 17, 2012, 04:28:22 am »

Yes it was.

MrSmith

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #2 on: June 17, 2012, 05:11:35 am »

there is less noise at 640 than 400 though.
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texshooter

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #3 on: June 17, 2012, 05:41:09 am »

you can see the chart here. jump to minute 9

http://m.youtube.com/index?desktop_uri=%2F&gl=US#/watch?v=zZRFlKdsHDg

someone told me these charts are meaningless because the camera was tested with the lens cap on. beware what you read.
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LKaven

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #4 on: June 17, 2012, 05:57:32 pm »

someone told me these charts are meaningless because the camera was tested with the lens cap on. beware what you read.

Beware of what someone told you.  Dark noise measurement is one proper way to measure sensor response.

I recommend this source:
http://home.comcast.net/~NikonD70/

langier

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #5 on: June 18, 2012, 11:47:03 am »

One of the things noticed using the 5D2 during the Great Zacuto Shootouts is that the in between ISO settings render cleaner images. I don't remember the particulars, but and of the multiples on the 5D2, 160, 320, 640, 1280, perhaps higher, gave cleaner vid than the normal ISO progression.

I don't recall if this was for all or just the 5D2. Worth checking their website for the comparison and then testing on your own.
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Slobodan Blagojevic

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #6 on: June 18, 2012, 12:03:59 pm »

I believe the explanation centers around the difference between shot noise and read noise. While one can be better at 640 than 400 (not sure about 100 though), the other type of noise more than compensates, thus the end result has more total noise. If I am not mistaken, the lens-cap-on test measures just one type of noise.

marcmccalmont

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #7 on: June 18, 2012, 07:17:29 pm »

Bill Claffs charts explain it well
http://home.comcast.net/~nikond70/Charts/RN_ADU.htm
If you ettr use 100, 200 400 etc for lowest noise if you expose for the scene then the 160 320 etc would be lower noise but not as low as ettr'ing
Marc
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Marc McCalmont

texshooter

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #8 on: August 15, 2012, 08:08:33 am »

You never want to PUSH the ISO. And be warned that PULLING the ISO will reduce the dynamic range by 1/3 stop.  It is always better to pull than to push. And pulling is better than NATIVE when shooting low dynamic range scenes at high ISOs.

http://shootintheshot.joshsilfen.com/2010/05/13/canon-hd-dslr-native-iso/

Also, this study shows that ISO 160 is no more noisy than ISO 100 for the 5DMarkII.  And it is a myth that ISO 640 is less noisy than ISO 400.

http://www.terragalleria.com/blog/2011/03/22/best-iso-for-low-noise-on-canon-5d-mk2/

« Last Edit: August 15, 2012, 08:10:55 am by texshooter »
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digitaldog

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #9 on: August 15, 2012, 10:30:24 am »

Don’t know (or really care) about a chart. But with an image, depending on the camera system and how one exposes (ETTR), a ISO 800 capture shows less noise than an ISO 100 capture:

http://digitaldog.net/files/100vs800iso.jpg
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Ellis Vener

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #10 on: August 15, 2012, 10:54:57 am »

Don’t know (or really care) about a chart. But with an image, depending on the camera system and how one exposes (ETTR), a ISO 800 capture shows less noise than an ISO 100 capture:

http://digitaldog.net/files/100vs800iso.jpg
Andrew: Can we assume you used flash as the lighting source in order to keep the exposure settings constant even though  there is a 3 stop difference in ISO settings or did you change your raw processing settings?
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digitaldog

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #11 on: August 15, 2012, 11:52:22 am »

Andrew: Can we assume you used flash as the lighting source in order to keep the exposure settings constant even though  there is a 3 stop difference in ISO settings or did you change your raw processing settings?

Nope, no flash. Everything set on manual. Just alter the ISO setting with original aperture and shutter the same.
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Ellis Vener

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #12 on: August 15, 2012, 12:01:46 pm »

Quote from: digitaldog
Nope, no flash. Everything set on manual. Just alter the ISO setting with original aperture and shutter the same.
So all you did was change the Exposure setting in Lightroom?
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digitaldog

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #13 on: August 15, 2012, 12:07:27 pm »

So all you did was change the Exposure setting in Lightroom?

Yes (I normalized the exposure as one would do with ETTR).
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EricV

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #14 on: August 15, 2012, 01:01:46 pm »

... depending on the camera system and how one exposes (ETTR), a ISO 800 capture shows less noise than an ISO 100 capture:
http://digitaldog.net/files/100vs800iso.jpg
  If increasing ISO did not improve noise, in a light-starved situation, it would be a worthless feature.  You have successfully demonstrated that the ISO setting does exactly what it is supposed to do.  Of course if you had provided 8x as much light to the ISO 100 test, that image would then be the one with lower noise.
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digitaldog

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #15 on: August 15, 2012, 01:05:43 pm »

If increasing ISO did not improve noise, in a light-starved situation, it would be a worthless feature. 

True although in this example it wasn’t a light starved situation. The same shutter and aperture was used for both captures.

Quote
You have successfully demonstrated that the ISO setting does exactly what it is supposed to do.  Of course if you had provided 8x as much light to the ISO 100 test, that image would then be the one with lower noise.

I only adjusted the ISO setting. But yes, had the 100 ISO image had those two stops more photons and had been equality normalized, it would look better than the ISO 800 image.
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texshooter

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #16 on: August 15, 2012, 03:37:34 pm »


I only adjusted the ISO setting. But yes, had the 100 ISO image had those two stops more photons and had been equality normalized, it would look better than the ISO 800 image.

So let me get this straight. What does the in-camera histogram look like for your two shots?   If the ISO 100 shot was exposed to the left and the ISO 800 was ETTR, then I can understand why the ISO 100 is noiser. The arguement I raised and the sources I referenced assume that each compared shot is normalized in camera, not in Photoshop (ie, exposed in the middle of the histogram in camera). If you compare apples to apples, ISO 100 will always have less noise than ISO 800.
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digitaldog

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #17 on: August 15, 2012, 04:17:09 pm »

So let me get this straight. What does the in-camera histogram look like for your two shots? 

I have no idea. Didn’t look, don’t care. I’m capturing raw data, the in-camera histogram is immaterial in this case.

Quote
 If the ISO 100 shot was exposed to the left and the ISO 800 was ETTR, then I can understand why the ISO 100 is noiser.

Yes, exactly! You got it. The ISO 100 was exposed to the left but based on what the incident meter (which hasn’t a clue about raw or ETTR) recommended.

But the important point here is the concept which some believe, that in all cases, an image captured at ISO 100 will always have a lower level of noise than one shot at ISO 800. That isn’t necessarily the case.

Quote
If you compare apples to apples, ISO 100 will always have less noise than ISO 800.

Agreed.
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EricV

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #18 on: August 15, 2012, 04:39:22 pm »

But the important point here is the concept which some believe, that in all cases, an image captured at ISO 100 will always have a lower level of noise than one shot at ISO 800. That isn’t necessarily the case.
This must be a misunderstanding.  Anyone who believes that ISO 100 is always less noisy than ISO 800, would have to believe that camera makers are maliciously supplying an adjustment knob which you can use to make your pictures worse.  The real situation is quite simple: when you have enough light to expose properly, ISO 100 will require 8x (three stops) more light than ISO 800 and will be less noisy.  Conversely, when you do not have enough light, setting ISO 800 will reduce noise, compared to simply underexposing ISO 100.  This is precisely the case in which you would use ISO 800, as a tool to reduce noise.
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digitaldog

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Re: ISO 640 has less noise than ISO 100....WT@#?
« Reply #19 on: August 15, 2012, 04:41:36 pm »

Anyone who believes that ISO 100 is always less noisy than ISO 800, would have to believe that camera makers are maliciously supplying an adjustment knob which you can use to make your pictures worse. 

I don’t know what they believe but I hear this all the time.
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