Re: 35mm in 120 cameras (was: wide angle Bronica filmback

[Clive Warren <Clive.Warren@xxxxxxxxxxxxx>]

At 5:47 pm +0000 1/12/97, Willem-Jan Markerink wrote:

>On  1 Dec 97 at 15:12, Clive Warren wrote:
>
>> Brilliant!  Would you care to share your technique with us?  I will be
>> using a Koni Rapid Omega 6x7 rangefinder so can happily use the opaque IR
>> filter.  The focussing dial is actually marked for IR.  I was thinking
>> about modifying a couple of 120 reels to provide "guides" to keep the film
>> straight both when re-rolling and winding on.  Of the two methods I have
>> developed conceptually, one requires the 120 paper to be cut in 35mm
>> strips.......
>
>One big question is whether you really need the paper backing.
>Remember, you can't load or unload HIE in daylight anyway, so that
>argument is out (although it wouldn't surprise me if 35mm HIE tucked
>in 120 format backing would be perfectly shielded against all
>daylight, unlike in a 35mm cartridge....).
>
>I also assume there won't be a film counter on the back door.
>
>This leaves us with the potential of scratching the back of the film
>(no problem in a 35mm camera though), insufficient film plate
>pressure/film flatness problems, and insufficient film transport
>because of the thinner layers of film (btw, does any mechanical
>transport take into account the *number* of exposures for the exact
>amount of transport? The last shot on a roll requires less rotations
>of the take-up spool than the first shot, simply because the
>additional layers result in a larger diameter on the spool.
>

The paper should provide a little bit more protection for the back of the
film, and all pressure plates are not without cutouts/indentations.....

Film plate pressure and flatness are both dealt with adequately by the
Koni-Omega system, which actually moves the pressure plate forwards as the
shutter is released.  As the numbers of exposures increase, the wind on
lever allows less and less movement to take into account the larger
diameter of the take-up spool.




All the best,

              Clive   http://clive.bel-epa.com


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