John,
I went in the direction similar to what you suggest. So far my findings are:
1. FA 50/1.4 is spot on AF with central sensor. Same front focus issue
in MF mode.
2. FA 77/1.8 is spot on w.r.t. AF and similar front focus issue in MF.
3. On K10D I cannot determine if I have any MF issues. K10D also has
Katz Eye screen.
I've contacted Rachael Katz and she suggested that modern AF Pentax
cameras have wider tolerances w.r.t. manual focusing assembly precision.
I intend to contact Pentax Israel and ask if they would be willing to
try to calibrate the screen (using special shims). As far as I
understand all that has to be done is slight change of the screen
position inside the camera. Depending of what Pentax Israel response
would be, I should decide my next step.
In principle I could try to focus a bit beyond the point of focus as
present position of the focusing screen indicates. The problem of course
is that it is somewhat hit and miss game and that it changes from lens
to lens. I've been spoiled with relatively precise MF of my K10D using
similar Katz Eye screen so that I am a bit frustrated, but at least I
seem to have a plan.
Last but not least, the responsiveness and willingness to help of Rachel
Katz is to be commended by highest praise. Truly amazing service.
Thanks!
Boris
On 12/17/2009 7:45 PM, John Sessoms wrote:
You eliminated what I hoped might be an easy answer, so I think your
next step is to determine whether it affects all of your lenses or just
the one.
I think you next should determine if the FA50/1.4 has the same front
focus problem. Also whether it's a problem in auto focus as well as
manual focus.
Possible outcomes:
1. It's only the A50/1.2.
2. It's the A50/1.2 & FA50/1.4, but only in manual focus.
3. It's both lenses in all modes.
I don't know which you'll get, but it seems to me they would point to
three different problems:
1. the lens
2. the screen
3. something else (I don't see how the screen would affect auto focus).
Of course, I was wrong before.
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