Boris,
I understand that soft focus lenses, on some systems,
will not "come to focus" within the limits of the AF
program.
I've read of a number of problems with infinity focus
which have had to do with critical mirror alignment
and bumper wear. Seems these aspects tend to reveal
themselves at the long end of focus. Can't guess why.
Have you gone to manual focus and tried backing off
and otherwise fiddling with the focus?
Jack
--- Boris Liberman <[EMAIL PROTECTED]> wrote:
> Hi!
>
> Some time ago, which unfortunately, I cannot
> pinpoint with any
> accuracy, my F 85/2.8 has developed a very strange
> problem. Most
> recently it has manifested again on my *istD, and
> finally it forced me
> to seek for help.
>
> The problem is with infinity focus. By the way, yes,
> this lens allows
> autofocus, and it works, both on *istD, and on MZ-6.
>
> So, the problem is like this. When pointed to
> infinity the lens would
> come to focus mechanically. So I would see that
> whatever I am shooting
> is in focus. The motor would stop, so the AF stops
> hunting. However,
> focus confirmation indicator would start blinking,
> as if the lens
> cannot be brought to focus. Furthermore, in *istD,
> the center AF
> indicator would blink in read, as if it sees the
> focus. Ultimately, I
> wouldn't be able to release the shutter because AF
> confirmation does
> not confirm.
>
> I tried different apertures from f/2.8 to f/5.6 (the
> range where
> aperture is fully mechanic). Same outcome. If I try
> to focus just a
> tad closer than infinity - voila - proper focus,
> nothing fancy.
>
> The first time I encountered this, I cleaned up AF
> coupling of my
> MZ-6. But *istD seems to have stronger motor and its
> AF coupling is
> clean.
>
> What gives? What to do? One of the main reasons that
> I bought this
> lens was indeed AF. To focus manually soft focus
> lens is beyond my
> eye-vision :(.
>
> Thanks in advance.
>
> --
> Boris
>
>
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