On Dec 14, 2009, at 12:21 AM, Boris Liberman wrote:
Larry,
On Mon, Dec 14, 2009 at 9:37 AM, Larry Colen <[email protected]> wrote:
I think that this means that the focusing screen is not properly
calibrated.
I ran into this problem on my K20D. Rachel Katz said that with the
K20s, the
number of miscalibrated screens went way up. In my case, they had
measured
the necessary shim for the focusing screen then accidentally put
two of them
in. At least I assume that is what happened because when I took out
one of
the focusing screens it was right on.
My suggestion is to try it with several lenses, wide open and as
close as
the lens will focus to minimize depth of field. If you can, also
test it
with the lens on auto focus while you're at it.
Write which lens and auto or manual on a small card that you put in
each
shot so you can tell what is going on when you look at the pictures.
Do you suggest that I take the measurements and then send them to
Rachel Katz as an indication that I may be needing a replacement
screen?
Not screen, you may need to get another shim behind the screen. What
you may need to do is figure out if it is front or back focusing, and
by how much at what distance. Then you take out the screen, take out
the shim, measure the shim and find out what thickness shim that you
need.
Shims aren't very expensive, you may be best off getting an assortment
of them before removing your screen.
In any case, what you should do is take the measurements, with several
lenses, quantify it, then ask Rachel for her advice. I suspect that
you would run into the same problem with the stock screen, if you
could see well enough to focus it accurately.
--
Boris
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--
Larry Colen [email protected] sent from i4est
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