Making a webcam to Cheshire eyepiece adapter.

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Friday: I turned an adapter from the unknown white plastic bought locally. First I bored all the way through to 28mm+ to make  the camera a snug fit. 

Then I reversed the material in the lathe and carefully checked for concentricity. The larger bore for the body of the Orion Cheshire eyepiece could then be bored out.

The adapter was very simple to turn out of plastic using a ceramic tool. The step in the bore between the diameters required for the webcam and the Cheshire eyepiece can be seen here

By inserting the Cheshire and then the camera they could be brought face to face. Or separated slightly to alter the sharpness of the cross-hairs and field of view.

I connected the camera to the computer and took a snap of the result with the open Cheshire pointing towards a window. The image right shows the result.

The plastic was easy to turn and much softer than brass or aluminium. Making it an ideal material for a snug, sliding fit for the camera and Cheshire without causing cosmetic damage. Nor did I need locking screws.

Finally I had to bore a 25mm hole in the side of the adapter. This was to act as a light port for the reflective 45 Cheshire window. The nearest size I had was a 26mm woodworking spade bit. Which suited the job perfectly. It was important to maintain the pressure on the drill press to avoid the pilot hole becoming too large too soon. Some slight deepening of the bore in the lathe and the two windows coincided nicely.

The next stage is to try the collimation assistance set-up on the telescope.  More to follow soon:

All the plans of mice and men.. The image on the laptop was easily transferred to the tablet but was too dim on both screens. A snap taken of the laptop screen appears alongside. The inner ring shows the Cheshire and its cross are concentric. However, the reflections coming back from the lens did not show up well enough to be useful.

A quick peek through the Cheshire with the MkI eyeball easily showed the scattered spots of light from the misalignment I had just caused by adjustment. The batteries of the small, diode torch I was using to illuminate the Cheshire were a bit flat. So it was much dimmer than usual. It fitted nicely in the side hole of the adapter but just needed to be much brighter. I'll take a better image in daylight tomorrow. I had to paint out the flash on this one.

I should try new batteries. If that fails I shall use my much brighter LED front cycle light to see if that helps. I'm now wondering if the camera is dimming the view because of the bright cross in the center. Black paint on the cross-wires might help but would thicken them even more. Painting the back of the cross might also be difficult.

How important is the wire cross anyway other than for initial alignment? I can check the alignment of the Cheshire from the objective end. It's considerable length makes it easy to see any misalignment. Only its non-standard [nominal 1.25"] diameter is causing problems. I checked repeatedly when I was looking through the objective earlier. Just to see if I was doing something wrong when I couldn't see the reflections from the lens on the screen. I had to change to a better 2":1.25" compression band adapter to straighten things up.  

Click on any window for an enlargement.

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