Because your eye is trying to focus on the image too. Then you have two different systems working against each other. The trick is to focus you eye on something distant then grab the first snap into focus on the ground glass. Try it, it works.
There is another technique where you focus on the ground glass surface. You can fiddle to your hearts content if you can do that properly, but it is a skill that takes a while to learn. I was never good at it unless I had a scribe line to hold my eye focus which is why I like the grid screen. The snap focus one can be learned by most folks with a few minutes practice. Tom C wrote: > To each his own then. The intimation made (not by you) that people do not > know *how* to focus without a focusing aid though is absurd. > > It's obvious that when it appears that it's in focus it probably is. As far > as readjusting focus after one thinks they are there... what does it hurt > graywolf? If one achieved focus in the first place, then moved off and back > on just to confirm, then it's just as likely they achieved critical focus > the second time as well. > > Tom C. > >> From: Godfrey DiGiorgi <[EMAIL PROTECTED]> >> Reply-To: Pentax-Discuss Mail List <pdml@pdml.net> >> To: Pentax-Discuss Mail List <pdml@pdml.net> >> Subject: Re: Katz Eye Split prism screen >> Date: Wed, 24 Oct 2007 10:00:48 -0700 >> >> On Oct 24, 2007, at 9:37 AM, graywolf wrote: >> >>> Just to give the other point of view, I hate split image focusing >>> devices. To me >>> they are annoying, right in the middle of the picture where I want >>> to see what I >>> am looking at, and they are not as accurate as you guys seem to >>> think they are. >>> Plain ground glass with grid is my choice. It is interesting how >>> many folks do >>> not trust their eye. >>> >>> In my opinion that is because they do not know how to focus a >>> ground glass >>> image. The trick is to trust that first instant when the imagae >>> snaps into >>> focus. If you start fiddling the focus back and forth your eye has >>> time to try >>> to adjust itself, and you will never get right. I have always found >>> that I get a >>> higher percentage of properly focused images that way than I do >>> with autofocus. >>> That method has a couple of other advantages; it is very quick, and >>> you can >>> focus anywhere on the screen. >> I've replaced split image rangefinder focusing screens with a plain >> matte focusing screen in virtually every SLR I've owned since 1968 >> for exactly the same reason. I don't even like too many scribe >> markings near the center of the focusing screen, they get in the way. >> >> Godfrey > > > -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
