Flat focus base with screws for 3 inch focus lens, for DIY | Starlight

If you build your own telescope or if your professional Dobson has a square cage, there is often no ready-made adapter for your focus lens. This flat focus lens base for a 3 inch focus lens from Starlight Instruments is screwed onto a flat surface, after which the focus lens is mounted on it.

With the screws, you attach the focus lens to the light path. This is the case with self-assembly and with Dobson telescopes important, because the focus lens must be placed directly opposite the viewfinder.

Make sure the surface is solid and really flat before you start drilling. After assembling, line the focus unit with a laser, like the High-accuracy laser for 1.25 and 2 inch, And only then can you align the mirrors. How to do that step by step can be read in our explanation about collimation.

If you have a 2 inch focus lens, then there is one flat mounting base for 2 inch.