T-2 BBHS® Mirror Diagonal

These informations might help you with your project https://www.baader-planetarium.com/en/blog/optical-tube-lengths-of-2-clicklock-and-bbhs-mirror-diagonals/

Yes, both nosepiece and eyepiece clamp work fine with this star diagonal. The spacer rings are not necessary. They fulfill two purposes: 1) They increase the optical length and are used for finetuning the distances especially for photography 2) They fit between two T-2-parts which are screwed together and make it easier to unscrew them. If you screw two metal parts together and e.g. the temperature changes, it can be hard to seperate them again. With these plastic spacers, it is easier to unscrew them again. But this is only interesting if you change the parts quite often and not if you want them to stay together.

The Baader T-2 BBHS ® Mirror Diagonal is not designed to be collimated. Technically, it is possible with the Baader 2" BBHS ® Mirror Diagonal.

Unfortunately we have only just now noticed, that a colleague has answered this question incorrectly. When removing the male T-2 thread, you will reveal a female M36.4 thread on the mirror housing instead of a female T-2 thread. This is the adapter that is used in this mirror: https://www.baader-planetarium.com/en/baader-adapter-m36.4--t-2-(t-2-part-03).html

Yes, you can remove the male T-2-thread to get access to a female T-2-thread.

We recommend the BBHS mirror diagonals generally for apochromatic refractors. The prisms are preferably used when there is a short backfocus or other reasons that might speak against a mirror.

The optical length is the length which it adds to the light path. In this case, the threads do not contribute because the "dissappear" when you place the star diagonal between two T-threads. The optical length is not always identical to the mechanical length, because the lenses in some parts change the focus point. It gives always the movement of the focus point when the part is used as intended.