On Jun 15, 2008, at 11:54 AM, Boris Liberman wrote: >> Focusing screens with split image focusing aids are very sensitive to >> being exactly on the lens optical axis for clean imaging with the >> focusing aid. > > I just got a reply from Rachael Katz herself. Boy, that was fast, > and it > is Sunday! > > It turns out that if I move my eye to the left and to the right > ever so > slightly (never thought of this direction) - it helps to bring the > darkening to become symmetrical (both top and bottom portions of the > split screen) and screen is indeed usable at least at f/8 in moderate > tungsten light. I just tried it right now. > > My understanding is that I did everything properly up to the > production > tolerances. > > Most probably, I will simply have to use the screen extensively in > order > to get used to it. > > Nonetheless, I couldn't focus my A 50/1.2 at f/1.2 and be sure of the > precision of the focus before I bought the screen. So undoubtedly > it was > worth it.
Yes indeed: alignment with the optical axis of the viewfinder system is very critical with some lenses, moving your eye around to find the 'sweet' spot is a good tactic. Rachael is right: use it a while. I'm sure it will work out to be fine for your needs. :-) Godfrey -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
