As has been said before, there are two separate optical systems 1) lens to focussing screen and 2) screen to eye - so that the diopter adjustment does nothing to the focus of the image on the screen. Adjust it so that you can see the screen best and forget it.
The AF does NOT 'see' the same thing as the screen. When the position of the AF module (that sits under the mirror) relative to the lens is different to the position of the screen, both result in a different focussing position of the lens. So if images taken using the Autofocus appear sharp, then maybe the focussing screen is out of alignment. However, using a 1.4 lens with manual focus on a ist D screen without focussing aids is a worst case scenario. If you really want to rule out focussing errors on your side you need to use a magnifier or refconverter in the 2X position. Sven Zitat von Gonz <[EMAIL PROTECTED]>: > I need some help with my *istD. For the longest time, I've been having > problems with my pics being quite soft wide open. I thought that it was > just because the lens was wide open. I have alot of manual focus > lenses, which I use often. The problem showed up mainly with them, so I > went back to look at some of the pics more carefully, and I noticed a > pretty consistent pattern. There were areas of sharpness alright, but > not where I wanted them to be. I was consistently back-focusing. So I > did some tests. I mounted my FA* 85 1.4 on the camera, set it on a > tripod, and proceded to make some careful experiments to see if I could > put the blame where it belonged, on me or the camera. > > The setup was your typical measurebating focus test setup. I had a ruler > at an angle with a target off to the side of it where I focused. I took > pictures with and without autofocus. The result: no matter how > carefully I manually focused, the autofocus was always right on the > money, and I always back focused. I adjusted the diopter after > autofocusing to see if I could match the camera's focus point, took my > glasses off, put my glasses on, danced around the camera, but no matter, > I always back-focused. What is going on here? Doesnt the autofocus see > the same thing I do? Or is something mal-adjusted somewhere? When I > look through the viewfinder after I auto focus, it seems to be in decent > focus, but it looks pretty much the same as when I focus manually. If I > then switch to manual focus and get it out of focus and back in and take > the pic, it is back-focused! Am I going blind? >
