Here is my first video tutorial covering compositing 32bit Linear OpenEXR multichannel files in photoshop, without altering the values and blowing out the images when stepping down to 16bit or 8 bit modes.
I hope it helps, as Photoshop is not really geared towards working with 32bit images, if you are rendering out linear images from your 3D package this is useful.
(DISCLAIMER – Download and install at your own risk)
Download the Linear RGB ICC profile used in this video here –http://bit.ly/sxn6gI
How to create your own Linear ICC profile –http://fnordware.blogspot.com/2008/05/making-linear-icc-profile.html