It has taken me a while to put together some images from the telescope, a Celestron 130 SLT. Since the arrival of the unit, I’ve wondered how to get neat pictures. Afocal didn’t work out, as I need additional spacer rings, and other expensive attachments. So I figured I’d go the low-tech prime-focus, using the recording media as the focal plane. I measured the diameter of the telescope’s eyepiece socket with some calipers, and took them to the local hardware store, Keystone. They have a small inventory at Keystone — just the basics, including this sink drain extension tube, for $1.79, which has a beautiful and snug fit inside the 1.25″ eyepiece socket.
I was hoping I’d be able to take off the threaded fitting, stuff the webcam in there, and thread it back on. No such luck in this case, and the next course of action is to cut off the wasted end. I did some rough calculations, and cut off all of the wider flanged piece, saving only about 1cm for a nice snug fit. Pipe cutters for copper do not work on flexible plastic, so I crudely whittled it down with a lockblade.
Looking down the tube, I noticed that the inside of the tube was reflective, which would produce some kind of ghosting. I used some discount black spraypaint I had laying around, and gave it several really light dustings down the tube. I could have done a much better job, but it seems to cut down on most of the inside reflections.
Then I popped a 25mm eyepiece into the telescope, and focused on the cell tower in the neighbors yard, a specific bolt to be exact. Then swapped the eyepiece for the tube. I held the webcam on there, fired up cheese, and tried to see something. After fiddling with it for a while, a very unscientific approach, I didn’t think this would work at all, and that I’d missed something. Eventually I realized that it was just out of focus, and I got beautiful orange leaves from the non-orange wisteria — the lack of infrared filter makes the image coloring kinda wonky.
I must have bumped the telescope, because I was no longer pointing to the cell tower. After re-aiming the telescope, I fiddled with the position of the plastic cover over the CCD element, to move the original target into the center of the webcam image. Interestingly, there’s quite a zoom effect when using such a tiny webcam because the element is so tiny, I suspect. Having piano hands, it took a while to get the thing centered enough to superglue the plastic pieces together. It popped off a couple of times, and I had to repeat the procedure until I finally got it.
I was very generous with the superglue, and made sure to wait for it to dry before applying more glue. I didn’t get too much on my fingers, though I did almost glue my hand to the USB cable. Be careful with superglue.
I was able to image Arcturus only, as the tracking was running out of batteries, and not tracking properly anymore. But I am excited about the image, after tuning out the noise it looks quite good for what it is.