[rollei_list] Re: Rolleiflex 2.8C Film Frame
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 29 May 2008 09:56:16 -0700
----- Original Message -----
From: "ERoustom" <eroustom@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, May 29, 2008 5:35 AM
Subject: [rollei_list] Rolleiflex 2.8C Film Frame
A Rolleiflex technical querry for a change. : )
I've been thinking a bit about the problem (discussed many
times already) of over exposure in a line along the top
of the frame.
Example here:
http://www.flickr.com/photos/elroustom/2422405163/
I was looking at the two vertical rails on either side of
the frame, that the film is pressed against, and noting
how much higher they are than the two horizontal limits
of the frame. I can understand the need to recess these
to avoid scratching the film as it winds past, but I
wonder if they are too low? Does anyone have a 2.8C and a
later model that does not exhibit this "Bug"? And can you
compare the difference in height between the vertical
rails and the horizontal ends around the film frame?
Illustration of question here:
http://www.flickr.com/photos/elroustom/2533890102/
Cheers,
E.
Its normal for there to be a slight gap. Lay a straight
edge one of the rails (the long way) so it extends over the
rollers. The top roller should be just about even with the
rail, the lower roller will have a larger gap. I am not sure
why its arranged this way but it may be related to the
difference in the angle the film makes with the take up
spool vs: the feeler roller.
The back plate does not really press the film against
the rails, rather it forms a channel for the film to run
through. The back is positioned by four "feet" at the edges
which contact reference surfaces just outside of the film
rails. Depending on the model when the plate is moved the
the 35mm position either the feet are moved to another set
of reference surfaces or there is a second set of feet that
contacts the same reference surface.
If my understanding of this system is correct the
tendency of the film to bow towards the back of the camera
keeps it relatively flat against the back plate. Since the
back plate is evidently what establishes the film plane it
must move for 35mm film to accomodate the difference in
thickness of the film plus paper of 120 vs: the thickness of
the film alone for 35mm plus the difference in thickness of
the stock.
Since the film is not pressed against the rollers there
is a small gap though which light can be reflected by the
rollers from the film gate to the space between frames or to
the next frame.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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