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Author Topic: Exposure and RAW,  (Read 3699 times)

DesertFox

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Exposure and RAW,
« on: April 30, 2006, 08:41:10 am »

I change my RAW files (Nikon D200 NEF) in CS2 to DNG format. Then I adjust the picture for the best setting.
The exposure can be set to 4 steps up or down. What effect does that have on the photograph? Does it matter whether I have exposed correctly or may I do it later in CS2 , even having been several steps off the correct exposure while taking the photo. Is there any need any more to bracket my photos while shooting?
Tom
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tived

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Exposure and RAW,
« Reply #1 on: April 30, 2006, 08:55:05 am »

Quote
I change my RAW files (Nikon D200 NEF) in CS2 to DNG format. Then I adjust the picture for the best setting.
The exposure can be set to 4 steps up or down. What effect does that have on the photograph? Does it matter whether I have exposed correctly or may I do it later in CS2 , even having been several steps off the correct exposure while taking the photo. Is there any need any more to bracket my photos while shooting?
Tom
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I personally think it still pays to do bracketing, which also can be used in HDR. pulling or pushing you are bound to that something is going to give!

anyway, its just my $.02

Henrik
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Tim Gray

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Exposure and RAW,
« Reply #2 on: April 30, 2006, 09:44:04 am »

I just finished a 9 day trip to Oregon and Northern California (Canon 1d2) - my guess is that for all the bracketed shots about half were, in fact, just fine with the auto exposure - but for the other half, brackets were required.  It goes without sayting the those "just fine" shots would not have been fine at all in jpg.
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Lisa Nikodym

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Exposure and RAW,
« Reply #3 on: April 30, 2006, 11:00:22 am »

Even with being able to change the raw file's "exposure", you can still get blown highlights that aren't fixable by the raw converter if you're photographing high-dynamic-range situations.  In those situations, it's best to bracket.

Also, if you have to increase the "exposure" in the raw conversion, you get worse shadow noise than if you took at it the optimum exposure to begin with.

Lisa
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61Dynamic

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Exposure and RAW,
« Reply #4 on: April 30, 2006, 12:18:04 pm »

Exposure is still important with raw just as it was with slide film or jpeg. The exposure correction tool should be thought of as a correction tool for mistakes in exposure or minor fine-tuning of exposure. Not a substitute of good photographic technique.

Over-exposing can be beneficial due to the Expose to the Right technique however, you need to be careful that doing so does not clip any important highlights as mentioned or over-saturate (such as with flowers).

In addition to more shadow noise when under exposing, your image can suffer a loss in detail and color accuracy as well (the latter depends allot on the camera).

Optimum exposure is very important if you wish to get the most out of your raw files.
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bjanes

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Exposure and RAW,
« Reply #5 on: April 30, 2006, 01:01:22 pm »

Quote
I change my RAW files (Nikon D200 NEF) in CS2 to DNG format. Then I adjust the picture for the best setting.
The exposure can be set to 4 steps up or down. What effect does that have on the photograph? Does it matter whether I have exposed correctly or may I do it later in CS2 , even having been several steps off the correct exposure while taking the photo. Is there any need any more to bracket my photos while shooting?
Tom
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The above exposure lattitude would be only for low contrast scenes. With a full scale scene, say a landscape with white clouds, whitecaps on the water, and other areas in shadow, you probably need the full 8-10 stops of dynamic range and don't really have any lattitude. If the contrast ratio is lower, you should expose to the right.

Bracketing is advisable for critical situations, but for less critical work, such as vacation photography, you won't go that wrong if you use your camera's histograms after determining if they allow for any headroom (with some histograms and flashing highlights, you can give as much as one stop additional exposure without actually blowing the highlights). In this situation I don't think another half stop of exposure to the right (assuming you are using a reasonably low ISO) is worth blowing the highlights. Afterall, even with 1 stop of highlight headroom, you still have  2048 levels with which to work. Noise varies with the square root of the number of photons captures. Halving the exposure only increases the noise by a factor of 1.4.
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DesertFox

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Exposure and RAW,
« Reply #6 on: April 30, 2006, 01:40:06 pm »

Thank you all for the informative replies. Will continue to bracket. Did not know about the 'expose to the right' technique but will apply it now. Great forum.
Tom
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