A simple secondary mirror holder for a diagonal mirror with a minor axis of 4 cm or more.
I designed this secondary mirror holder for my dobson telescope building project using a 203 mm diameter primary mirror and a secondary mirror with 70 mm of minor axis.
This simple diagonal mirror holder has the basic 3 screws at 120 degrees to tune the tilt of the secondary mirror. Rotation and translation back and forward the telescope tube is achieved thanks to the M4 screw.
It is a simple but efficient design.
I finally ended up painting the mirror mount flat black and I also did a small knob to easily tune the distance back and forward the telescope.
Updated the photos with the painted mount, nicer to look at the finished one!
I added the base part designed for M5 spider vanes for those who prefer a more robust spider vane even if it is not that necessary.
* 3 x cap head screws M3x45mm
* 3 x nuts M3
* 1 x pan head screw M4x65mm
* 1 x flat washer M4
* 3 x nuts M4
* 1 x wing nut M4 or normal M4 nut
* 1 spring
* Threaded rod M4 (for the spider vane)