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I just received my $27 split screen focus screen from Hong Kong today, and despite my usual fumble-fingeredness managed to install it without difficulty in probably no more than a minute. I purchased the little kit, which includes a couple of finger cots and two tweezers, one metal and one plastic, from ebay seller terence_camera. I placed the order on 12/10, and received it today, 12/26. I thought I would report my early impressions. First of all, the image in the viewfinder is not quite as bright as with the original Pentax screen, but it really isn't reduced enough to be a problem. Secondly, I've always kept my K10D set on center focus, and the red focus indicator shows up dead in the center of the ring unlike a report I read on this forum about one person's experience with the Katz eye. My slowest lens is my Bigma at 500mm which is f6.7, and there's no problem with the center prism area blacking out at this aperture. Interestingly, my camera's auto-focus seems to be dead-on with the focus screen. When the lens auto-focuses the two halves of the image seen in the prism are perfectly aligned. If there has been any significant change in the camera's auto-exposure, I've not yet detected it, although, as stated above, I just received it, and my experience so far is quite limited. I should point out that all my lenses are auto-focusing, so why, you ask, did I purchase this in the first place. My main reason was to be able to accurately focus the lens manually in conditions where there was not enough light for it to focus automatically. In this respect I may have wasted my money, because I can't improve manually on the camera's auto performance in low light. I plan on leaving the new screen in the camera at least for the time being, because I see no down-side to it. Am I unhappy with the purchase? No, not really, because it was the only way I could answer my question with certainty. Would I spend over $100 for Katz eye? No way, because I really find it difficult to believe that it would function significantly better than this Hong Kong special. Bottom line: for anyone using manually focusing lenses I think this is a definite improvement over the OEM Pentax screen and a perfectly acceptable, much less expensive alternative to the Katz eye. I hasten to point out that I have no experience whatsoever with the Katz eye, but really find it hard to believe that it would out-perform by any realistic degree this little cheapo.
Yours FWIW
CN