Topic: The Canon EF--and everything else--spotting scope adapter project
Oh, I spose, you guys'll tell me somebody in China already MAKES one.
I wanted to do thus:
Be able to use my Canon EF mount lenses, --and anything else--as a spotting scope. Because I can adapt my favorite lenses to my Canon EF mount camera (Adaptall, etc) this means that an EF mount eyepiece mount would also accomodate any OTHER lenses I have.
I bought a REALLY cheap extension tube set off the 'bay, intending to junk it just for the lens mount. Turns out I didn't even have to modify them, and could still use them. These are the import variety, REALLY cheap thread together set like these:
I also bought this telescope adapter piece:
Here's the start of the escapade. The tube at top is a piece out of an import T adapter setup to mount a camera on a reflector telescope. I'm thinking I might need it for a barlow. It screws right onto the ebay piece I just mentioned, pictured at bottom left of the picture below. The extension ring set, torn down, is shown at left. A thick washer I screwed up on one of the Minolta mirror projects is shown, as is a cheap "erector" mirror:
The picture below shows the washer which I relieved on one side to pilot into the EF lens mount, as shown
The picture below shows the washer lying inside one of the extension tube rings. I relieved the opposite side of the washer to pilot into the minor dia. of the extension tube, and turned the OD to fit inside the threaded area.
I had to play with the reliefs somewhat so that the washer would fit inside, yet the tube ext. ring would fit OVER it, and thread up tight against the shoulder. When assembled, the EF mount, the washer, and one of the tube rings, screw up tight and hold the washer captive.
Below, we have the washer, with the ID turned to a "convienient dia" and I just chucked the eyepiece adapter in the lathe and relieved the end to form a small pilot into the washer ID. Tomorrow, I'll just drill and tap 3 small holes through the washer/ adapter to hold the two together
Below we see the washer piloted into the EF mount, the eyepiece adpapter piloted into the washer. You next take one of the extension tube rings and screw over the top of the washer, thus holding the washer in place
This is what it will look like ready for the lens, without an "erecting prism" or "erecting eyepiece." From what I've surmized from the www, my cheap mirror erector won't work, because it "adds length" between the eyepiece and lens. I BELIEVE I've learned that I can cure this, maybe with a prism instead of a mirror, and using a barlow. If not, perhaps an "erecting eyepiece." For now, it should work, if not inverted!!
Last edited by 440roadrunner (2008-09-08 04:19:29)