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RH-50 70mm film back
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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Sat May 22, 2010 6:07 pm    Post subject: Reply with quote

My guess would be "convention". You won't be able to get a true 7cm frame out of 70mm film, and a 6.5cm x7 image would be painful when sent to the wedding lab. They would have to buy a special mask, charge you more, etc. etc.

I also think running the holder vertically would be mechanically problematic for everything but the Super Graphic.
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MarinB



Joined: 04 Jul 2013
Posts: 3

PostPosted: Thu Jul 04, 2013 5:34 pm    Post subject: Graflex RH-50 back modification to 56x112mm (61x125mm?) Reply with quote

How difficult would it be to modify a RH-50 back to 6x12 format? I would think you just need to file the window to maximum possible width (about 12 cm - but how much exactly?). Is the film flatness compromised by the absence of two pin rollers or should they be repositioned? Has someone on the forum done this already?
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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Thu Jul 04, 2013 5:52 pm    Post subject: Reply with quote

Well the pin rollers were added to the roll film holders because of a flatness problem, though when you space them 12+ centimeters apart, I think they are pretty much useless.

The bigger problem you'll have to overcome is the spacing. The gearing is still for 6x9, and Shooting frames 2, 4, 6... Might work, but you'd be waisting film (18+cm vs 12+cm).
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MarinB



Joined: 04 Jul 2013
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PostPosted: Fri Jul 05, 2013 10:06 am    Post subject: Reply with quote

Les, are you 100% sure the gearing is for 6x9? RH-50 is a 6x7 format back. A fellow from the UK, Colin Turner (who hasn't yet responded to my messages) had such a modification done by a mechanics shop. His results can be seen here: http://www.flickr.com/photos/57818412@N00/5430614132/
Though gaps between frames are irregular, the average looks less than 18 cm. He seems to be simply winding it twice.
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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Fri Jul 05, 2013 11:18 am    Post subject: Reply with quote

You are right, th RH-50 is 6x7 and not 6x9. My bad.
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MarinB



Joined: 04 Jul 2013
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PostPosted: Thu Aug 15, 2013 5:52 pm    Post subject: Reply with quote

How difficult would it be to re-gear or change the gearing in this back from 8cm to 12cm?
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europanorama



Joined: 17 Oct 2014
Posts: 3
Location: BASEL

PostPosted: Sat Oct 18, 2014 11:03 am    Post subject: Mount-versions-Restrictions or not Reply with quote

Les wrote:
I need to add a caveat to that. All of the colored lever handled roll backs can interchange shells and inserts providing the neg size is the same.

But the last version of the back, the ones that say Singer/Graflex and have either a thin chrome or thin black lever similar to a 35mm camera have a raised bump on the light trap of the insert that will not allow it to mate with an older RH shell of any size. That is of course until you file the bump down. The bump was designed to 'encourage' photographers to buy new holders rather than use the older ones.

I have this RH50:
Graflex General Precision with the 4pin-frame.
removed it is for 4x5
Its the version with yellow filmtransport lever labelled +g.
since its not chrome nor black mentioned above this bump("restrictor" which i name it) is not present. So i can add the 6x7-or 6x9 graflex insert. filmframe is 57x68mm.
I have an identical one in 4x5-version only(no 4pin-frame).
inside cartridge-chamber foam should be replaced.
I know the 4pin-version can be mounted onto RB67 without the rotating back. Does RB mean rotating/revolving back then? I also have the RB-70-back with vaccum.
Is there a site explaining all these mounts. Graflex, Graflex, RB. International 4x5.
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