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Old 23-05-2019, 09:21 PM
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Peter Ward
Galaxy hitchhiking guide

Peter Ward is offline
 
Join Date: Dec 2007
Location: The Shire
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Quote:
Originally Posted by Stefan Buda View Post
I need to make a camera adapter to mount a QSI683 on a CDK250 but the information I have does not make sense to me.
Can someone please explain to me how a filter or a window makes the required adapter shorter? Please read the small print about the back focus being reduced by the thickness of the glass/3.
Hey Stefan. It's because the focal plane of a converging light cone falls short by the stated amount with a plano element in front of a sensor.

The thicker the filter, the more the converging cone is refracted.

Yes, the refractive index of the filter also makes a difference, but likely an order of magnitude smaller.

Hope that sheds some light
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