Prototype of a Newtonian astrograph

We sometimes receive telescopes from the factory that have completely bent secondary mirror spiders that we can't repair. Over time, we've accumulated a few that are too good to throw away.

So one evening we sat down and thought about what we could construct with them. Suddenly, the idea of ​​an astrograph came up.

The initial tests, using a camera on a photo tripod in front of the Newtonian telescope, looked very promising, so we decided to build a prototype. The goal was to make it simple to implement.
 

The first components are shown here: instead of the secondary mirror mount, a new 2-inch mount for the eyepiece drive. We chose the TS Heli 2 here because it has an M48 thread on the eyepiece side and doesn't rotate during focusing.

For coma correction, we chose the MPCC Mark III from Baader.

From the MPCC, we have a backfocus of 55 mm, which is adjusted using a 16.5 mm M42m-M48f adapter and a 21 mm M42m-M42f adapter. For the tests, we used a ZWO ASI1600 MC with a 17.5 mm backfocus.
 

The images are sharp right up to the corners of the ASI1600MC, and no coma is visible.

Because the shape of the spiders was specially designed, typical spikes are not visible, but the stars are slightly more bloated.

The tests still need to be validated in the real sky; so far, we have only been able to conduct the tests using an artificial star.
 

(Sorry about the weird lighting, it's the lighting on the board, not the camera.)

Now it's time to get this into production... To be continued...