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11-15-2009, 02:57 PM   #1
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K-7, ovexposure and high ISO

I've just experimented with exposure on ISO 1600. I've overexposed +1 stop and pulled the exposure back by 1 stop in Photoshop, and noise looks much better. I would like to know from you guys how would that affect details in bright areas (I didn't notice any, but frame didn't have any critical bright areas). How much is the headroom in bright areas for K-7? falklumo?

11-15-2009, 03:04 PM   #2
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Is your overexposure causing highlight clipping? This is the most important question to ask.
Did you compare it with the same ISO 1600 shot without EV comp?
This has been an issue discussed before:
https://www.pentaxforums.com/forums/general-photography-techniques-styles/617...ose-right.html
https://www.pentaxforums.com/forums/general-photography-techniques-styles/630...ake-sense.html
11-15-2009, 03:31 PM   #3
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QuoteOriginally posted by Ash Quote
Is your overexposure causing highlight clipping? This is the most important question to ask.
Did you compare it with the same ISO 1600 shot without EV comp?
This has been an issue discussed before:
https://www.pentaxforums.com/forums/general-photography-techniques-styles/617...ose-right.html
https://www.pentaxforums.com/forums/general-photography-techniques-styles/630...ake-sense.html
Ash, thanks for the links.

I avoided highlight clipping, and yes, I shoot the same scene without EV comp. But, after reading previous topics, I'll reformulate my question: does "exposure to the right" have any sense particularly with K-7?
11-15-2009, 07:32 PM   #4
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you'v pulled from 1600, +1stop, does your picture differ from iso800 without EVcomp?

11-15-2009, 09:13 PM   #5
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Have you got an image of a particular scene? We could provide you with a better analysis and even provide you with some metering techniques to overcome having to push or pull an exposure.

Though I understand what you are doing but doesn't have much practical sense, especially in the digital age. Using 35mm film you could push/pull exposure to expose for scenes beyond the ASA capability of the film. The pushing / pulling was purely becasue switching out film and winding it back to the correct position was a pain in the ass and rarely worked without losing a bunch of exposures. For me anyway.

Personally I would avoid this technique with digital as ISO quality has improved substantially and there isn't anything wrong with a bit of controlled noise.

Last edited by King_Boru; 11-15-2009 at 09:22 PM.
11-16-2009, 12:51 AM   #6
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I agree that it doesn't have much sense, and, is fact, practicaly is same as shooting ISO 800. I was just experimenting, and was suprised that overexposure makes such difference in noise.
11-16-2009, 01:37 AM   #7
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It actually makes a lot of sense. There are two effects at play. One is the way in which data is stored. Because sensor data is linear, you store more data in the bright regions than the dark regions. Second, assuming noise is fluctuating but relatively constant, signal-to-noise ratio is inherently higher in dark regions than in bright regions.

Bottom line: if you are not clipping your highlights, and you care about the shadows, you will minimize noise by putting as much data in the lighter region of the histogram, whether that comes from adjusting the shutter speed, aperture, or ISO.
11-16-2009, 09:35 AM   #8
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QuoteOriginally posted by krypticide Quote
Bottom line: if you are not clipping your highlights, and you care about the shadows, you will minimize noise by putting as much data in the lighter region of the histogram, whether that comes from adjusting the shutter speed, aperture, or ISO.
How is that any different to simply exposing the scene using the "correct" settings without having to push or pull an exposure? There are a lot more cons using a higher ISO than noise. Color and sharpness being the key factors.

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