Sorry if I put this in the wrong forum, I wasn't really sure where it belonged. (I did do a search, but I didn't find an answer to my question.) In the next week or two I want to get one of the Katz Eye focusing screens for my 350D. (I just can't seem to manually focus accurately with the stock focusing screen.) My question is: Is the OptiBrite treatment worth it? It says that it makes the view finder brighter at smaller apertures - but the lens will always be at max aperture (unless I press the DoF preview button) until the shutter opens, right? Like on my 50 f/1.4 even if I stop it down to f/22, it's still wide open until I actually take the picture. I could be wrong, but it seems like the OptiBrite treatment is only beneficial if you're using a lens that actually stops down to whatever aperture you want to use before you take the picture (which none of my lenses do). Does that make sense? If I had lenses like that I could see why I might want to get the treatment, but will it offer any advantage at all if I'm always looking through the lens at max aperture? Sorry if I didn't explain it very good, hopefully I got my point across though.