I am very nearly 52 years old and I understand the double mirror system with no problem just from watching this video, however I am also an armature astronomer and am familiar with collimation having collimatied telescopes in the past.

Excellent information I never thought there was such a major difference between glass and plastic. I am going to double check my day pack right now.

Thanks for sharing your knowledge with public.

defiantly good info Mors, thanks for sharing your knowledge..... ....billyjoe

Thanks Mors, I always carry a small one but thankfully have never needed to use it outside of teaching. I think mine was a glass one from Cabelas. Any idea when more of your e booklets will be online @ Karamat I've been trying to be patient this last year since I first heard Mors mention it. Thanks again for another great video.

At 2:08 you showed a small plate glass mirror that you said "has a special sighting system, that we'll talk about", but I don't think you have got to it. You discussed the double-sided mirror system later, but I think what you were showing was a retroreflective mesh system, like a commercial Coghlan's mirror or a military MIL-M-18371E mirror. Is there another video where you discuss this type?

Thanks for that important lesson! I always carry my mirrored compass for the eye, facial and dental issues. But my signal mirrors are plastic. Time to look for a glass signal mirror. Are there any brands you recommend?

What is the name of that TV mirror? Thank You.