First post on this forum, just wanted to share a diy filter holder to put inside of the Russian lens Tair3.
A cls ccd filter on the front lens(72mm) cost a lot, so I decided to use a 42mm Astronomik(no filter mount) and model a "inside lens" holder for it.
When using a aps-c camera, the filter holder(and the 3 screws) is not visible. No vignetting.
I haven't tested with a full frame.
Files are available here:
Can be filament printed or abs like resin.
I will test it as soon as the weather allow it