Re: [APML] Focus Problem with Pentax 67

[Roland Roberts <roland@astrofoto.org>]

>>>>> "dk" == D Kodama <kodama@alumni.caltech.edu> writes:

    dk> I've seen the same problem in my Pentax 67, expecially when
    dk> shooting at f/4 or faster, and especially on negative film which
    dk> I think is thinner than positive film.  I went to a vacuum back
    dk> and haven't seen any problems after that.

I should have given more detail; I was shooting E200 at f/5.6.  I was
very pleased with the framing and exposure NGC 7000 :-/  I spent the
morning looking at Hutech's vacuum back for the 67....

>>>>> "kgk" == KGKIRKLEY  <KGKIRKLEY@aol.com> writes:

    kgk> The Pentax 67 cameras can use either 120 or 220 film.  120 film
    kgk> has a paper backing along it's entire length while 220 film
    kgk> only has a leader and trailer.  220 film has twice the length.
    kgk> There is a control on the side of the camera that switches from
    kgk> 120 to 220 and this moves the pressure plate in or out, out for
    kgk> 120 and in for 220.

    kgk> You're 'gross donuts' might indicate it was set for the wrong
    kgk> film, this allowing the film to change position or buckle.

>>>>> "jd" == Joseph Dunning <josephdunning@bellsouth.net> writes:

    jd> On my camera the control on the end of the camera only changes
    jd> the frame counter. The back must be opened to move the pressure
    jd> plate between the two positions. There is a window in the center
    jd> of the back showing the pressure plate position.
 

I'll double-check the setting on the pressure-plate.  The side control
was definitely set at 120 (and still is).  I distinctly remember seeing
the setting on the pressure plate, but it's always possible I botched it
(who me?)

I think I may also purchase the IDAS LPS filter so I can do some tests
from here in Brooklyn.  It's not a cure for our grossly bright skies,
but it will let me shoot some more shots and see if I can get the
problem to go away.  Anything that lets me practice without having to
leave home is a good thing.

roland
-- 
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Roland B. Roberts, PhD                             RL Enterprises
roland@rlenter.com                            6818 Madeline Court
roland@astrofoto.org                           Brooklyn, NY 11220
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