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Reflector telescope using Walmart mirrors $130. This telescope has visible mirrors and is good for students to learn how a reflector telescope works.
The F number, 3.6, is very low. This gives a short tube and wider field of view but low magnification. This telescope's large mirror and low F number make it better for star clusters and nebulae (the M objects, Messier catalog) but not good for planets. With a 2x Barlow and 20mm eyepiece, the Moon is pretty nice, about 60% of the Moon is visible at once.
Photos during telescope build-up are below.
The concave, F3.6 mirror, 8" diameter, needs this hole reinforcement in the center to aid in alignment. This target doesn't take away from viewing because it falls in the shadow of the diagonal mirror up above. The "mirror cell" is cereal-box cardboard.
A plumb bob helps locate the optical center of the telescope, up at the eyepiece structure.
Looking in from the side, seeing the 8" mirror by reflection in the diagonal.
The eyepiece-mount structure showing the template which locates the centerline of the mirror.
The 300 yard tall antenna mast, about two miles away. By eye, it looks a lot better than by smart-phone photo. This was taken just after the first alignment of the optics, Aug 19 4PM. The next step is to look at the moon and planets, if they look OK then I can order good eyepieces, Barlow lens, laser collimator, 1.25" focuser. It takes a lot of reading on Internet to decide eyepiece focal lengths and 1.25" or 2" focuser. Eyepieces can be 25mm and about 15mm, and a 2x Barlow gives equivalent of 12.5mm and 7.5mm. 25mm is the largest for the F3.6 mirror, SkyandTelescope site on Internet says max is 7xF ratio = 25.2mm. Another Internet source says max magnification for this telescope is 200X, which would be with eyepiece focal length 3.8mm, probably not a good image or not good eye relief below 7mm.
A nice 20mm eyepiece and 2" focuser are in the telescope, now. Alignment is not the best and star images are not great. But the best use of this F3.7 telescope is nebula and star clusters, where focus is not the critical thing. It is worthwhile purchasing a Barlow lens to go 2x on magnification, but I don't want to spend $200 on a finder, just yet.
As the construction on the "optical tube assembly," OTA, finishes up, I can turn attention to pointing the telescope. Alternatives to traditional mounts are interesting. A web site offers the calculations to translate time and RA/Declination to altitude/azimuth, and Python can do that.
With Barlow workable (not sure an improvement yet), go on to alt-azimuth "mount." The C clamps are clamping sections of the telescoping strut.
The pivot for the altitude is just blocks that the front legs ride in.
The telescope mount has received some improvements. Altitude adjust with telescoping strut is more convenient with new C clamps, and LEDs are added so you can see the controls when you are under a dark sky.
Other LEDs for convenience when under a dark sky. The altitude protractor is prominent. Sometime, the azimuth compass, and boat compass, will arrive.
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