I purchased a K10D along with the 16-45 f4 lens 4 months ago. I purchased the Pentax because I have been a Pentax user since the late 60s and have heaps of Pentax lenses in both screw and K mount. Few are auto focus because I am a MF kind of guy.
Focusing with these older lenses has been difficult to the point that I just zone-focused them or left them home and relied solely on the zoom. I started to do some resolution testing and found that the in-focus indicator was rather general rather that spot on. Trying to determine sharp focus in the finder is difficult even when using my focus magnifier-M.
I had read several threads about focusing screens from China as well as the Katz-eye screen available from
Katz Eye™ Optics - Custom Focusing Screens I elected to go with the later and ordered a screen without the OptiBrite but with the "rule of thirds" and "8x10" frame markings. It arrived yesterday and I installed it this morning.
The first thing I did was check the focusing accuracy and found it to be spot on. I then went about retesting some lenses using USAF charts. The difference between resolution between the first tests and those using the new screen were remarkable.
After being pleased with the results, I checked the metering with old K-mount using the "green button" and Av with the old Takumars. In both cases, I found the metering to be much closer that with the original screen. For what ever reason, this new screen has really impressed me and I feel that it has added to the flexibility of the system and ease of use. I am very happy.
Cheers,
Bob Rapp