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11-13-2009, 07:58 AM   #1
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Raise ISO or Brighten in Photoshop?

I've got the K7 and was wondering whether it would be more effective to increase the exposure of an image using Photoshop CS3 than to raise the ISO on camera. Is this a stupid question?

Another photoshop question: Are there any better ways to increase a photo's exposure than the usual Brighten/Contrast or Curves in terms of preserving picture detail?

11-13-2009, 08:14 AM   #2
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Not stupid at all. For normal shooting you are better off raising ISO -- at some point (usually after ISO 1600) pushing the image in post processing will yield the same (possibly better) results if you shoot raw format.
11-13-2009, 08:48 AM   #3
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Awesome. Very good advice
11-13-2009, 08:57 AM   #4
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Use Adobe Camera Raw

Actually, an underexposed photo is most easily adjusted in ACR. Open the photo in Bridge and use the Exposure slider, then send the image to Photoshop for other adjustments. Brightness in Bridge also gives better results than in PS.

In Photoshop, if you're just brightening, Levels would be my first choice. Curves work better if you want to tweak the contrast at the same time. In CS3 or better there's an Exposure Adjustment Layer that's better than Brightness, which generally should be your last choice.

And absolutely increase your ISO up to 1600 (with NR). At 3200 it's a wash between using a noise reduction plugin or faking more light in post production. The camera captures the actual information, but with a lot of noise. Photoshop simply decreases the amount of black in the image.

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11-13-2009, 12:58 PM   #5
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I find it's almost better to slightly over espose and darken in pping than it is to uner expose and try to pull the levels up at high iso's.
11-13-2009, 01:19 PM   #6
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If JPEG, definitely use in-camera, if RAW, it doesn't matter as much.

Also, it's always better to expose to the right without clipping detail with regards to shutter/aperture noise wise as there are more bits and more light, but I don't think it matters as much if you are only changing ISO.

Last edited by Eruditass; 11-13-2009 at 02:11 PM.
11-13-2009, 01:21 PM   #7
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It's personal choice as much as it is shooting with PP in mind.
I tend to expose for the subject, and consider the background only if it adds dimension to the image. Once the subject's in order, PP can focus on bringing out the background to complement the subject.
11-13-2009, 02:05 PM   #8
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FWIW, in not very scientific testing, I've found that nailing the exposure at ISO 1600 results in less noise than shooting ISO 800 and then pushing 1 stop during PP.

This is with a K100D & K2000, though, not a CMOS sensor.

11-14-2009, 07:25 AM   #9
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some reading

Noise, Dynamic Range and Bit Depth in Digital SLRs -- page 3
11-14-2009, 08:40 AM   #10
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That is a *very* interesting article.
Thanks Jeff.
11-14-2009, 09:13 PM   #11
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QuoteOriginally posted by mysticcowboy Quote
Actually, an underexposed photo is most easily adjusted in ACR. Open the photo in Bridge and use the Exposure slider, then send the image to Photoshop for other adjustments. Brightness in Bridge also gives better results than in PS.

In Photoshop, if you're just brightening, Levels would be my first choice. Curves work better if you want to tweak the contrast at the same time. In CS3 or better there's an Exposure Adjustment Layer that's better than Brightness, which generally should be your last choice.

And absolutely increase your ISO up to 1600 (with NR). At 3200 it's a wash between using a noise reduction plugin or faking more light in post production. The camera captures the actual information, but with a lot of noise. Photoshop simply decreases the amount of black in the image.

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How Brightness/Contrast works in CS3-4 was improved greatly over CS2 and earlier though. In fact I would never use it in CS2 but now I go to it every once in a while when other methods are flat or I even use it in combination with other methods.
11-15-2009, 12:52 AM   #12
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Basically, your camera stores more data in the higher light range of your exposure, so it's best suited to shoot at a higher ISO (giving more data) than to push a lower ISO (less data).
11-15-2009, 06:45 AM   #13
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QuoteOriginally posted by krypticide Quote
Basically, your camera stores more data in the higher light range of your exposure, so it's best suited to shoot at a higher ISO (giving more data) than to push a lower ISO (less data).
If I understand what you are referring to (bit levels) then I consider that a urban legend based on Emil's data and others.
Naively it would seem obvious that the highest quality image data would arise from concentrating the image histogram in the higher exposure zones, where the abundance of levels allows finer tonal transitions.

However, the issue is not the number of raw levels in any given segment of the raw data (as measured e.g. in stops down from raw saturation point). Rather, the point is that by exposing to the right, one achieves a higher signal to noise ratio in the raw data. The number of available raw levels has little to do with the proper reason to expose right, since as we have seen the noise rises with signal and in fact the many raw levels available in higher exposure zones are largely wasted in digitizing photon shot noise (there will be more to say about this in a moment, when we consider NEF compression).

The fact that level quantization much finer than the noise is superfluous, since noise erases the perceptual impact of abrupt tonal transitions, means that many of the levels used to record higher exposure zones are unneeded and indeed wasteful -- photon shot noise is much larger than the level spacing in midtones and highlights on a typical DSLR.
That is, if the average photon count is 10000, there will be fluctuations from pixel to pixel of as much as sqrt[10000]=100 photons in the sample. Suppose each increase by one in the raw level corresponds to counting ten more photons (i.e. the gain g=10 photons/ADU); then noise for this signal is 100/10=10 raw levels. The linear encoding of the raw signal wastes most of the raw levels, since the noise is much larger than the quantization step.
In shadows, it's a different story. Suppose our average signal is 100 photons; then the photon fluctuations are sqrt[100]=10 photons, which translates to +/- one raw level for the supposed gain g=10. At low signal level, none of the raw levels are "wasted" in digitizing the noise.

Which means this is correct but NOT for the reasons stated:
http://www.luminous-landscape.com/tutorials/expose-right.shtml
11-15-2009, 08:18 AM   #14
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Wow, you technical types really go to the mat on this stuff, don'tcha?

My right-brained take-away from this thread is, "Expose to the right as much as possible--without blowing out highlights! Beyond that, the right mix of iso, shutter speed and aperture is a judgment-call based on the situation and the effect you're trying to achieve but don't be paranoid about high iso values--technology has improved considerably (thanks to the left-brainers ;~) so that iso 1000 isn't nearly the disaster it used to be."
11-15-2009, 08:41 AM   #15
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