----- Original Message -----
From: <chatanooga@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, December 12, 2005 6:56 AM
Subject: [rollei_list] Re: 2.8FX shutter cock and film
advance 'synchronisation'
thanks carlos. The behaviour as you describe is definitely
how it should be
- ie foolproof. Shucks!
I just made a test on an MX Automat using a dummy spool
and card to fool the film feeler. The crank stroke needed to
cock the shutter is quite short compared to the stroke
needed to wind film at the beginning of the roll, about
enough to get the crank pointing straight forward. The
shutter is locked out until the crank is returned to its
neutral position but once there the shutter will fire.
Because of the metering arrangement the crank stroke varies
throughout the roll, becoming shorter as more film is wound
up on the take up spool. So, its necessary that the shutter
cocking function be complete with a little less than the
minimum crank stroke ever needed for winding film. So,
especially near the biginning of a roll, its possible to
wind the film only partially and still fire the shutter and
move the counter. The crank must be moved to the limit of
its movement for each frame. I didn't measure how much film
is moved when the crank is moved just enough to cock the
shutter but it may be short enough to cause overlaped
frames, at least in some parts of the roll.
A way of checking this is to sacrifice a roll of film to
use as a test tool. In older Rolleis its possible to fool
the camera that the back is closed when a button or lever
actuated by the back is held in. Once this is done one can
observe the winding and mark the frames with a pencil to
check the amount of movement. I suggest doing this before
sending the camera off to be serviced to make sure there
actually is a problem and that your camera works the same
way as the one I checked.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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