A question I’ve been asked quite a few times when at public astro society events concerns the black box that is perennially attached to the side of my 200P Newtonian. I’ve also been surprised how many people, who seem otherwise fairly adept with astro kit on various astronomy forums and the like, don’t seem to know what Telrads are or how they work. A quick search has turned up very little in the way of video on the subject.
To me, the Telrad is one of the most singly wonderful and useful things that I’ve ever added to my collection of Kit.It makes alignment so much easier than it ever was with a mangifying finderscope, to the extent that I now have a guide camera attached to my finderscope permanently, and don’t use it as an actual finder at all.
I’ve made a quick video, explaining what a Telrad is, and why you want one (or something similar!).
By the way, I forget to mention in the video that the three circles are 1/2, 2 and 4 degrees when superimposed on the sky, and you can get charts that utilise Telrad circles to help you find things visually. It’s also possible to vary the brightness of the reticle via the variable on/off switch.