I was hoping I would be able to post this image proudly stating: "Look how close you can get to a Samyang 135mm for just $30" . However, that is clearly not the case. The aberrations are so severe that the data was basically unsalvageable. (And for those curious I used an aperture mask to bring it to f4 hoping to prevent odd star shapes with the blades) Regardless, a lot of the fun for me is in the journey of the project and not necessarily the final result.  In this case I had quite a good time putting this all together.

This had originally started when I sold my DSLR and was stuck with a cheap 50mm auto-focus lens.  I wanted to figure out a way to attach that to my ASI533MC AND be able to control the focus motor and aperture. You can see some details of that here. I felt that the image  I managed to get with that $50 lens was pretty good and since I'm always looking for a project I thought I would try converting an even cheaper vintage lens to auto control and see what happens.

The lens I bought was a Tamron 135mm f2.8 made in the late 70s, it was $30 shipped from ebay.   The reviews for terrestrial use seemed pretty good especially considering the cost. 

Over the years I've accumulated a small machine shop in my basement with a CNC controlled mill and lathe, however I got my first 3D printer about 8 years ago and it suddenly seemed that every problem or idea I had was just a few clicks away.  If I could 3D print a telescope, I would. Essentially every accessory on this rig is 3d printed.  The scope rings for the camera, the ring gear for the focuser, the stepper motor mount,  an adapter to turn a 2.5 pound dumbbell plate into a counterweight, the vixen dovetail plate was 3d printed before I bought an aluminum one. For anyone curious about making their own auto-focuser,  I use the excellent myFocuserPro2 project for all of my telescopes which allows me to build an entire solution for less than $15.

Anyway, it was fun but I doubt I'll be using this lens again.  I used this for my first dual rig imaging sessions which was an adventure in itself. Perhaps a story for another time.