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aligning a c-mount som berthiot zoom


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#1 ishan vernallis

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Posted 26 September 2007 - 12:46 PM

I recently purchased a C mount 17-85 som berthiot dog leg zoom to use on a non-reflex bolex rex16.

The problem is that when the lens is screwed in all the way,
it does not mount in a manner so that the dog leg viewfinder can be attached to the lens.

I've seen pictures of how this lens is supposed to fit onto the camera,
but this one sets the viewfinder mount so that the dog leg
would be running through the bottom of the camera body.

Does this mean that the lens mount is way out of whack and needs to be collimated?

Where does one get the calipers...
(or whatever they are actually called)
the two point wrenches,
that enable one to turn the c-mount threads and other parts
of a lens. It seems like if I could just screw/unscrew the cmount further/less into the lens
that all would be well.


Any Ideas?
Thanks!
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#2 Jean-Louis Seguin

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Posted 26 September 2007 - 02:53 PM

I recently purchased a C mount 17-85 som berthiot dog leg zoom to use on a non-reflex bolex rex16.

The problem is that when the lens is screwed in all the way,
it does not mount in a manner so that the dog leg viewfinder can be attached to the lens.

I've seen pictures of how this lens is supposed to fit onto the camera,
but this one sets the viewfinder mount so that the dog leg
would be running through the bottom of the camera body.

Does this mean that the lens mount is way out of whack and needs to be collimated?

Where does one get the calipers...
(or whatever they are actually called)
the two point wrenches,
that enable one to turn the c-mount threads and other parts
of a lens. It seems like if I could just screw/unscrew the cmount further/less into the lens
that all would be well.
Any Ideas?
Thanks!




You have to rotate the thread C-mount ring until the alignment is just right. Berthiot made a special tool that fits into the two little notches in the ring but if you don't have the tool, I'd suggest using a block of hard rubber to turn the ring. I've seen people use pliers but it's too easy to slip and scratch up the rear of the lens. When adjusted right, the zoom stick should be pointed straight down.

Jean-Louis
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#3 Lou Nar

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Posted 16 April 2009 - 10:54 PM

I'm glad I found this posting, I had a similar alignment problem. The rubber block trick worked like a charm.
Thanks JL!
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Rig Wheels Passport

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Wooden Camera

New Pro Video - New and Used Equipment

FJS International, LLC

rebotnix Technologies

Gamma Ray Digital Inc

Technodolly

Metropolis Post

Tai Audio

Visual Products

CineTape

Paralinx LLC