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RE: [Rollei] Right back for 220 TLR?



> I've not seen it stated for Rollei, but it makes sense.  Cameras
> which switch the pressure plate for 120 or 220 do so to compensate
> for the difference in thickness of the two due to the lack of backing
> paper on 220.
>
> Bob

Hi Bob,

I've always been curious about this, and never really spent the time to
investigate it (except for our previous discussion on the vacuum back on the
RTS III).

It's a given that the film, whether 120 or 220 is typically (...except when
using a vacuum system) registered against the front side of the film channel
closest to the lense (typically on some machined rails)...and, at least in
my 120 cameras the pressure plate presses against "stops" that maintain a
fixed distance between the pressure plate and the front rails, making a
"channel" for the film to slide through without any "binding".  35mm does
this same thing.

But...does the 220 setting not use the stops, or have different stops,
therefore changing the film channel size, and without stops, the pressure
plate does in fact press the film against the front rails, causing some
binding?  Do some cameras have a second set of stops that are used when the
pressure plate is moved over to the 220 setting?

My Fuji GS645, which is switchable between 120 and 220...has stops for the
120 setting, but none for the 220 setting.  That would mean no "extra" space
in the film channel only enough for the film, that the film has constant
pressure on it between the pressure plate and the front rails.  This is
unlike 35mm, which maintains free space in the film channel, at least in my
Contax and Leica cameras, and 35mm film doesn't have backing paper either.

My Pentacon TL does support both 120 and 220, but does not have any
different pressure plate setting.  Also, on the Hasselblad list, there was a
discussion that the pressure plate and the case etc. are all the same for 12
or 24 backs, the only difference is the advance/counter mechanism...and if
Hasselblad believes there is no need for a difference, I am curious why
others believe there is.

Does anyone have any more information or thoughts on this?

Austin

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