Larry, as far as I recall, the Katz Eye focusing screens (according to
Rachael Katz herself) on K-7 (*) typically required 0.2 or 0.25 mm shims
instead of the stock one. I think that mine was calibrated by 0.2 mm shim.
I should point out that the service I received from Rachael was truly
amazing as she helped me all the way through. I have this e-mail
exchange archived and it is more than 25 e-mails worth.
Having said that, I do remember clearly that just a single attempt was
enough.
On 6/6/2012 04:19, Larry Colen wrote:
I'd love to be able to plug 12" distance, 3/64" front focus, and
whatever the shim thickness is into a formula, and get the correct
shim thickness on the first try. I suspect that what I'll have to do
is measure the shim, change the shim to the next thinner, try the
same setup, and then interpolate between the two to get the proper
thickness.
I doubt such a formula would exist. You see, the problem as far as I
understand is that manufacturing process is inherently imprecise and
these imprecisions are quantifiable only in statistical terms...
Oh, and by the way, the shims I got from Katz Eye Optics were marked by
their respective thickness - no need to measure. Nor do I have an
equipment that can provide accuracy of 0.1 mm anyway...
So I humbly suggest you do it by trial and error. I reckon you might be
able to look up the thickness of the stock and Katz Eye screens on the
web and measure the thickness of your specific screen (should it be not
Katz Eye). Then you would be able to figure out the shim thickness based
on the assumption that 0.2 or 0.25 mm is a reasonable starting point.
HTH.
Boris
(*) I can only hope that the situation with K-5 is the same as that with
K-7, as I hope that this kind of production tooling wasn't changed
between the two cameras.
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