Mission Objective

     My primary goal modifying my C-130 Maksutov is to increase the telescope's usability and compatibilty with commonly available accesories. I would also like to improve function by limiting light scatter, increasing contrast, and reducing the cool down time. If all goes as planned this telescope should be greatly improved; not to mention beautiful, all telescopes should be pleasing to the eye.

     I am redesigning the plastic back assembly to acheive the above goal. The back of the scope needs to be simplified. I did away with the flip-mirror design in favor of a more standard 1.25" eyepiece threaded adapter. To cut costs on the prototype I have designed the threads to use the same as the C-130 so I can simply unscrew the stock eyepiece adapter on the the flip mirror, and thread it into the new back. Later models I produce may have standard sct threads, or I may include an adapter for such. The inside design is clean and simple with no complex angles to bounce light, I have also planned for an anti-reflective finish on the inside to help improve contrast. I have chosen aluminum as the material for the back, as it is light weight, easy to machine, and excellent at dispersing heat. I have not made provisions for collimating from outside of the back. I may install a crayford fine focuser and fear the collimation holes might interfere with the focuser mount holes, so I have left this feature out for now. After many hours spent drafting up plans on autocad, I have reached a design I am ready to move forward with.

Prototype Stage

The aluminum back starts it's life as a solid billet of 6061 aluminum extruded to the nominal diameter of the part. It is then cut down to the nominal thickness at the factory before being shipped. It arrives in the condition shown.

     The lathe operations are complete (thanks to my friend Wes from Accu-Right - BoatLadder.com) and the rough fit and finish is very nice. It is a much better fit than the sloppy, shameful plastic back that came with the scope. Now I just have a couple of operations to perform on the drill press to finish the millwork on the prototype. I will be drilling the three mounting holes as well as counter-boring each to accept cap screws. I will also bore three 1 inch collimation holes so I can adjust the collimation without removing the aluminum back; a much desired feature and improvement over the plastic back.

This photo shows the part after all lathe operations have been completed, just a couple of drilling operations to finish millwork.

It fits very nicely in the original case, and overall fit on the scope is super precise down to less then 30/1000ths of an inch. Thanks Wes!

     I have finished drilling the prototype and have mocked up the part on the telescope to ensure a proper fit. The telescope is now beginning to look and feel like a real optical instrument, and I am very happy with the current results. All there is left to do is send the part out for annodizing, and upon return apply the anti-reflective internal coating.

Here the part is shown with the dust covers in place.

     I got the part back from the anodizing company today and put together a before and after picture. The black anodized finish came out very nice, it has retained it's metallic appearance. I was worried it would come out overly flat, so I am happily satisfied. I have since applied the anti-reflective internal coating, and it has really taken shape. Now I must wait two weeks for the anti-reflective coating to finish outgassing so it will be safe to be in close proximity to the optics. The two week wait for curing may be an extreme measure, but having a hazey film on the scope's optics would be an extreme disaster, so this is a precaution I simply must take.

Annodizing before and after.

Here is the anti-reflective coating photographed with full on flash, notice how flat and evenly dispersed the light is.

The prototype is now complete. Below is a picture of the scope taken just before it's first light. After initial testing, there is a noticable increase in contrast, and decreased cooling time. Those benefits added with the ability to finely collimate the telescope makes all the hard effort worth while. I am still accepting pre-orders in hopes to get the production numbers up to something economically sensible.

Mission Complete.