RAW/NEF question

[beej]

I shoot everything in RAW, and import the files into PhotoshopCS using Adobe Camera Raw for further refinement.

Situation A:

Load NEF in ACR
Change exposure to +1
Load into photoshop

Situation B:

Load NEF in ACR
Leave Exposure at 0
Load into photoshop
Change Levels (White Point) to increase Exposure to +1

Is there any difference in those two situations? To my untrained eye, I don't see any change? But is there an advantage in using the Exposure slider in ACR than modifying Levels in Photoshop?

The same could be said to makings changes to Shadows and Brightness in ACR, and Black Point and Gray Point respectively in Levels.

Cheers
- beej

[dooda]

Good question. As a newbie to Raw I've wondered the same thing.

[digitor]

Once you've taken the picture, you can't change the exposure. The exposure setting in ACR, as far as I can tell, adjusts the gamma of the curve. It all works as expected unless you run out of dynamic range! You've probably already noticed that if you decrease the "exposure" setting, blown highlights are still blown.

Cheers

[SoCal Steve]

Beej - This is what Bruce Fraser says in his book "Camera Raw with Adobe Photoshop" (http://www.adobepress.com) ....

"Along with the White Balance controls, the Exposure slider is possibly the most critical tool in Camera Raw- if you don't take advantage of the WB and Exposure tools to optimize your captures, you're essentially negating the benefits of shooting Raw."

"At positive values, the effects of the Exposure slider closely mimic increasing the exposure using the on-camera controls. At negative settings, its behavior depends on whether or not the image contains any completely clipped pixels - that is, pixels that are blown out in solid white in all three (color) channels. If the image contains no completely blown pixels, the Exposure slider works very much like reducing the exposure in the camera" (and some highlight detail can actually be recovered).

I found the book readable and understandable, but just a little scattered. What I mean is the same things seemed to be re-answered in different way in different places without much explanation why. Or maybe it was just me. I definitely would buy it again, though.

[beej]

Thanks for that Steve.