dslr folks question about exposure compensation and raw

[unsped]

a friend asked me a question and i wasnt real sure on the answer as ive had some conflicting experiences.

as you know a raw files you gain some exposure flexibility post process.

if you have a + or - exposure compensation value dialed into the camera does it move the baseline of that raw file upper and lower in comparison to a raw file taken without compensation ... ie are you changing the boundaries of the possible exposures?

example (where | = boundaries of raw exposure in post processing, and 0 = nuetral exposure)

RAW - no compensation
_________|----0----|
RAW - negavitve compensation
_____|----0----|
RAW - positive compensation
____________|----0----|

where zero would be if you imported the raw into photoshop and set the exposure value to zero.

my thought up to this point is that the exposure compensation only affects the shutter or aperature for a given shutter. which will have the net effect of giving you a different exposure range on your raw file

 

[gaidin123]

I believe you are correct. All the exposure compensation seems to do is adjust the exposure time (or aperture) up or down depending on how you have it set. If I understand you correctly by setting the exposure compensation one way or the other will just shift your overall range in post processing. I'd set it if your subject matter is always over or underexposed by your camera, otherwise if it's generally good enough just deal with it in the post processing stage.

Gaidin

 

[FilmCamera]

I'm not sure what you are getting at, but I suppose it depends on the camera.

Whether you have exposure compensation dialed in or not, the exposure adjustment will be at 0 in your RAW editor, unless you have some sort of defaults saved or something. The exposure compensation does not just bump up that slider if you adjust it to add say +2/3 stops of exposure.

 

[ghostman]

Not sure if this answers your question:
(source: http://www.photoxels.com/tutorial_raw.html)

Exposure Compensation

Some photographers have mistakenly thought that RAW allowed them to correct exposure errors. Well, to a limited extent, that is true.

However, a picture has to be correctly exposed, whether you are using RAW or not. You cannot take a grossly underexposed or overexposed picture in RAW, and expect to be able to "correct your mistakes."

To explain how this is possible, we need to get a bit technical: While JPEG captures 8 bits of colour per pixel or 256 shades of colour per pixel (16.7 million colours), RAW captures 12 bits of colour per pixel, translating to 4096 shades of colour per pixel (68.7 billion colours). This great amount of information (extra pixel depth going from RAW to JPEG) is what allows the exposure to be corrected up or down by one stop, and sometimes by as much as 2 stops (but you might be pushing your luck). Applying this exposure compensation and adjusting the other settings to your RAW data in post-processing may be enough to salvage an otherwise ruined image.