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Ben Langlotz

Adapting telescope to large-mount Arri IIC

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I’m preparing something of a museum display of a rare Questar Cinema Model based on a Questar telescope and an Arriflex 35mm IIC camera, and need advice about properly configuring the camera.

The desired setup is depicted in this Questar Advertisement. 

It was created by the late cinematographer David Quaid with Questar, and as a Questar collector I obtained his example from his daughter.  I have since obtained an Arriflex IIC for mounting on display, and perhaps even using.  I have two challenges:

  1. The scope came with a flanged Arriflex mounting plate that adapts to the standard camera threads to connect to the telescope, as seen in the photo below.  This has a 69mm outer flange diameter.  The camera has a larger mount that receives an 83mm diameter flanged body cap plate marked “Panavision.”  This mount is centered on the film frame, not setup for a turret as I best understand it.  I simply need to know a source on either a mount that adapted from a male 83mm flanged plate to C mount (or P mount) camera lens threads (I forget with, easy to adapt), or to modify this or another body cap plate for threads.  Because both camera and scope are supported, this does not need to be a robust connection.

  2. The camera needs a 1.5” base to elevate the optical axis into alignment with the axis of the scope.  The camera has a handgrip motor that is mounted with a 0.75” thick bottom plate to the motor can extend upward for a flat bottom camera.  The Questar Cinema models are depicted with a 1.5” motor/base that does the job - presumably the system was designed for these.  Some are labeled “Cine 60”.  Others are depicted with a different motor base.  Getting the terminology for these motor bases correct would aid my eBay searches, as well as that for the lower profile one I might sell on Ebay to fund the alternative.

IMG_1605a.jpg

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The telescope mount looks like it might be Mitchell BNCR, while the camera is possibly Panavision‘s PV 65. Is the bore 83mm in diameter?

It‘s a pretty unusual mount on an Arriflex 35, where did you pick that up?

The camera base that adapts the motor to the side is called a flatbase, Cine 60 made a lot of them. 

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The camera mount looks identical to the one on my 2C. It's a BNCR conversion.

IMG_3563.JPG

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This is a helpful start.

I'm finding that there are no adapters that go the other way (from the male BNCR flange to a conventional thread for) while everyone seems to need adapters for BNCR lenses, and not for cameras.  Maybe the solution is to obtain or use the existing body cap plate and drill and tap it.

How about the idea of un-converting the camera back to a conventional lens mount?  Are there easy parts lying around, or is this a major and pricey effort for a hobbyist suggesting I should sell the camera and try to find one that suits without modification?

The flat base info is good.  I also wonder whether I might find a thicker vintage one and sell the modern one.

Thanks for the help so far.

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If the camera is BNCR mount (which looks likely) it should have a throat diameter of 68mm.

If the scope mount is simply Arri PL you could look for a PL mount Arriflex, which should be easy enough to find though probably more expensive because it's the most commonly used contemporary mount. (Converting it to PL yourself will not be simple as the BNCR throat diameter is much larger.)

But the scope mount looks a bit different to PL in that it has holes in the flanges, rather than cut-outs. The outer diameter of PL flanges can vary a little, but usually they are under 68.5mm. Many camera  PL mounts have lock rings that won't accept 69mm flanges, so you may need to machine down the outer flange edges.

If it is PL, the throat of the scope mount (which would be the outer diameter of the shiny ring protruding slightly from the mount) should be 54mm. The original ad is from 1971, which was more than a decade before the PL mount was introduced, so either this is something else or it was modified to PL later.

Finding a BNCR mount to fit the scope is the other option, but may be tricky. You could ring around some older rental houses or repair/resell places like Visual Products or places that modify old lenses like TLS or P&S Technik and ask if they have any old BNCR mounts you could have. 

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