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CCD to Mount Flange Distance Questions

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#1 mattflastro

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Posted 07 May 2013 - 08:47 AM

Most video (and astro video) cams being derived from surveillance cameras are using either a C or CS lens mount.
The specifications for CCD sensor to mount flange distance for C and CS mounts are clear.
However, it appears (after measuring different camera models from different manufacturers) that even if cameras use C/CS lens mounts, the flange to CCD distance varies quite a bit from the mount specifications.
This creates a lot of problems, starting with lenses that don't come to focus and ending with not knowing what accessories could or couldn't be used with the camera , what spacers to use with various scopes, field flatteners etc.
Is there a database , website, or even individual manufacturer models specifications that show the _actual_ CCD to flange distance for the most commonly used astro video cameras ? Mallincams , Stellacams, Watec, Gstar, Mintron, Orion , Samsung 435, 2000, 4000 ?

#2 ccs_hello

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Posted 08 May 2013 - 06:52 AM

Matt,

in general, videocam vendor should adhere either to C-mount or CS-mount spec. including "flange-back distance" spec. If not, many complains or returns will show.

The mfgs sometime put an adjustment knob (drives a helical screw) to allow moving the CCD sensor module back and forth. Sometimes it is used to match with (cheap) lens not designed to spec.

I doubt there is a database collecting the manufacturing tolerance or goof-ups. In my book, it's just C or CS. (Factory native mode does not count, e.g., Samsung has a native one which always need a ring to bring it to spec.) No more and no less. If doesn't work, add shim, extender, change the mount type, or change the lens.

P.S. adding a focal reducer changes the focal plane distance (moves further in.)

Clear Skies!

ccs_hello

#3 mclewis1

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Posted 08 May 2013 - 09:44 AM

C-Mount - 17.52mm
CS-Mount - 12.52mm

Older Mallincam video cameras (AFAIK < serial# 369) - 15.8mm
Newer Mallincam video cameras - 12.5mm (this is referred to by Rock as "CCD forward" position)






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