Zeiss Jena focusing telescopes

[Piter_]

Hi.
Photo projection objectives of Zeiss Jena are made for projection distance of 125mm.
Below are listed different focusing attachments.
Circled in red.

Screenshot_2022-09-04-00-14-50-612_com.paperpile~2.jpg (69.96 KiB) Viewed 893 times

My question is how they can use the same camera connection tube from above if length of focusing attachment differs between different types.
Anyone can comment?
Thanks.

[blekenbleu]

Based on experience with Nikon and AO/Reichert, those parts are not merely tubes,
there at least beam splitters (e.g. half-mirrors or prisms),
and perhaps (as in e.g. Nikon type T and UW trinocular heads) some lenses.

[Piter_]

Ok.
I think it has to do with a glass plate shift of focus.
I have to compare one with a beam splitter and one with a sliding mirror.

glass_plate.png (22.79 KiB) Viewed 858 times

formula_plate_shift.png (2.82 KiB) Viewed 858 times