Is there any difference if you just don't process it before conversion and do all the processing to the TIFF after converting with photoshop? Do you lose anything by going this route? Thanks for any thoughts,
From everything I have read it is best to do as much processing as possible before converting to a TIFF. I use Phase One DSLR for RAW processing. I adjust brightness, contrast, levels, curves, and color in that program then I convert to 16 bit tiff. I don't know enough to explain why this is better, but I know the pros all do it this way.
Once I have a 16 bit tiff I stay in 16 bit for as long as possible in PS. Then I convert to 8 bit and make a few more minor adjustments.
RAW and TIFF are equals in terms of image quality, as both are uncompressed formats that can handle the same exact amounts and types of pixel data, utilizing the same bit depths and color profiles.
The key differences are the order of values in the data that gets saved, and what types of tricks they use in the headers to tell specific software special things. In RAW files, the headers are about how the camera was set, or what it may have done to compensate for what it thought was an incorrect exposure. A RAW reader will interpret all that data, and give you a rendering that's probably as close as the camera manufacturer thinks it needs to get in order to draw a correct representation. At that point, using your RAW reader to make exposure edits, or changing to TIFFs for use with Photoshop (which can do tons of things that RAW readers alone cannot do) is really your choice. As long as you aren't changing bit depth or color profiles in the conversion, you won't lose any data.
Because the file types are basically technical equals of each other, the real issue becomes what type of media you're displaying your stuff on, and the quirky things it might do while trying to display your chosen file format.