Originally posted by little laker I wonder if that's just a Pentax thing.
No. I first saw the issue described in detail by either an Olympus user:
Manual Focus with AF DSLRs
But I've also seen it discussed with respect to Nikon and Canon. Baiscally, it's a question of whether the focus screen is optimized for use with "kit" lenses or whether it is optimized for faster lenses. Focus screens on pretty much any entry level camera would be likely to be optimized for entry level lenses. And it totally makes sense that the Katz-Eye would be optimized for faster lens.
Here's a simple test for someone who has a fast lens and the Katz-Eye but is *not* having problems; I'd be curious to hear what folks say. Open the lens up wide, aim at a newspaper at a 45 degree angle, focus anywhere you like, and make a mental note of how many lines of text appear to be in acceptably sharp focus. Actually, best to note both the first and the last such line. Then take the picture and examine it and see if the results match. They definitely don't with the stock screen. With my A50/1.7, there are lines of text at both ends of the focus range that I can read clearly in the viewfinder but are hopelessly out of focus in the actual picture.
An even simpler test would be to simply pont at the target and do a DOF preview to see if anything changes. Wide open, nothing should of course. But each time you stop down, you should see more of the image coming in to focus in the DOF preview. What I see with my A50/1.7 is no discernible difference at all stopping down to f/2.0 or f/2.4 - not even in brightness. Stopping down to f/2.8, I do at least see a very slight dimming, but if there's any change at all in DOF, it's minimal. not until f/3.5 can I say there is a difference I'd have a chance of identifying reliably in a blind test (ie, where I didn't know which was supposed to have the greater DOF).
Originally posted by RiceHigh I would still suggest that you should insist for a replacement from Pentax so that at least the *standard screen* by Pentax should work just fine, before you go further adjustment or customization for the MF and AF.
Have we actually established there is a problem when using the standard screen? If the problem is just in the shimming of the Katz-Eye - as seems perfectly likely - it may well be there that is nothing wrong with the stock screen placement. Unfortunately, for the reasons I am describing, that's harder to test than it seems at first - but not impossible. You just need to really pay attention to the whole zone of acceptable focus in the viewfinder and image to see if they are actually *off* in the sense of something being *in focus* in the picture that wasn't in the viewfinder, or if it's just a matter of not everything that was in focus in the viewfinder being in focus in the picture, which unfortunately is absolutely unavoidable with the stock screen.