[APML] Bill Mattil Focus

[warhen@mindspring.com]

Hi Bill, Just to rehash what the true experts have said, f4 is indeed tougher to focus. Barring film creep or imperfect optics, perfect focus across the entire frame is achievable.

Unlike my F2, it sounds like your screen is exactly parfocal with the film plane. Even w/ a Hartmann mask and a 20x microsope, precisely focused on the screen's bottom was off.

That being said, I'd second the advice and stick with what works, perhaps with a higher powered loupe.

Let me add that for me, the Mitsuboshi from Hutech gives me absolute perfection every time. It is quite diferent from the usual knife edge, providing an unusual but foolproof pattern.

Feel free to contact me directly for further discussion.

Warren  

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