Film-Tech Forum ARCHIVE: XCN lamphouse with 35 and 70mm

This is topic XCN lamphouse with 35 and 70mm in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Schaffer (Member # 1204) on 01-19-2007, 04:04 PM:

Quick question: I have a Xetron XCN 4k console here with a Century JJ projector head for 35 and 70mm. In addition to the classic lamp focus assembly, the lamphouse has an adjustment to move the entire xenon block incl. reflector forward and backward. It says what the working distance for this reflctor is in the manual, but it doesn't say how to adjust between 35 and 70mm. I can't remember right now, does the reflector have to be all the way forward for 70mm and all the way back for 35mm (because it's more focused then on the narrower aperture)?
I guess the working distance given in the manual is for 35mm because that is more common. I am not there right now, but I will measure it later when I go back to the location.

Posted by Louis Bornwasser (Member # 3063) on 01-19-2007, 04:35 PM:

You are 100% correct. Full forward is about right for 70mm. Louis

Posted by John Walsh (Member # 168) on 01-20-2007, 10:58 AM:

The 4K and higher reflectors are about 15 inches diameter. This is the actual reflective area; the overall diameter with the front flange is about 16 inches.

The distance from the rear flange to the aperture for 'standard' 35mm projection is 31.75 inches. For 'standard' 70mm it's 30.10 inches.

I think some early reflectors did not have a rear flange, but I'm not sure. If yours does not, subtract 0.54 inch from the above. The manual gives a distance that implies 'no flange', so I would guess it was not updated when the flange was added. Which, sorry to say, makes it a bad manual.