----- Original Message -----
From: <chatanooga@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, June 05, 2006 6:35 AM
Subject: [rollei_list] rollei focus adjustment questions
> Listers
> I've pretty much convinced myself that my 2.8FX tends to
> focus about 3cm in
> front when nominally foucussed at 1m. I've verified this
> after noticing
> quite a few f2.8/ f4 type closeups didnt seem to be
> optimally sharp. I did a
> few angled-ruler type tests and shot several frames in
> quick succesion at
> the same focus to average out any film flatness issues. I
> see small shifts
> but the focus error is consistently in the front.
> Assuming the error is due to some fixed mechanical offset
> between the taking
> and viewing lense I'm wondering is this going to have a
> pro-rata effect at
> larger distances (for the same wide aperture)? My
> suspicion is it won't but
> would be interested to hear from someone less
> optically-challenged..! And
> suppose I put a Rolleinar on..........
> I would guess the 3cm I mentioned is equivalent to a very
> small film-plane
> offset - is such a small tweak possible (for the service
> centre, etc)?
> rgds
> Chat
>
To check this you need a piece of ground glass that will
fit against the inner rails and inbetween the outer rails of
the film gate. Because the film runs in a channel between
the inner rails and the back plate this may not be the exact
position of the film but will be pretty close. Use a high
power magnifier of good quality to check that the image is
in focus on this test GG when it is in focus on the finder
GG. The subject can be at any distance. The magnifier should
be about 10X minimum. If the focus is off the finder lens
must be adjusted. This is not a trivial job because it
requires removing the cover from the lens board. I suggest
making the test and if you find the focus is off send the
camera to one of the better Rolleiflex techs.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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