(The information listed below is excepted from my upcoming book, The DAM Book, to be published late summer by O'Reilly.)
Adobe, and specifically Thomas Knoll, has done an excellent job of creating Auto settings to apply in Camera Raw. They are not optimum for all images however. Situations where you want to disable auto include:
+ Images with lots of 255 255 255 white in them. In general, Auto will try to recover these highlights, to keep large parts of the image area from blowing out to white, so they won't look right in Auto.
+ Images, like stage photographs, with lots of very dark areas that you would like to keep as dark areas.
+ Images that have been exposure bracketed. Auto will largely remove the differences between these frames, making it difficult to determine which is the best exposure.
Solution: Make a "No Auto" setting in Camera Raw, save it, and apply it in Bridge when you know you don't want Auto exposure correction. (If you know that you never want Auto, then save it as the Camera Default.) Select all the files for which Auto is not beneficial, and go to Edit>Apply Camera Raw Settings, and choose the No Auto setting. Here's what the procedure looks like:
Making the No Auto Setting in Camera Raw:
Step 1: Open an image in Camera Raw

Step 2. Uncheck the Auto boxed over the exposure Sliders

Step 3. Use the Flyout menu (that triangle in the circle) next to the Settings pulldown to Save this setting as "No Auto"
Step 4. Quit Camera Raw (with or without saving the image)
Using the No Auto Setting from Bridge:
Step 1. Select the Images you don't want to Auto correct

Step 2. Go to Edit>Apply Camera Raw Settings>No Auto. Auto will now be turned off for the selected images.
Back to the Bridge Page