Other people, including photographers, don't see this version of you. They see a version that you are rarely privy to, and that can seem wildly foreign to our ingrained sensibilities. As Slate explains , it's a bit like how people hate their own voices on tape, doubly so because we know that those foreign, goofball intonations represent that way that everyone else hears us. In photos, we see ourselves in various states of motion, in different contortions and from uncaring, neutral perspectives. Lenses may distort, sure, but in a powerful way, these uncomfortable photographs are closer to reality than our carefully images in the mirror.
Telescopes and other precision instruments use front silvered or first surface mirrors , where the reflecting surface is placed on the front (or first) surface of the glass (this eliminates reflection from glass surface ordinary back mirrors have). Some of them use silver, but most are aluminium, which is more reflective at short wavelengths than silver. All of these coatings are easily damaged and require special handling. They reflect 90% to 95% of the incident light when new. The coatings are typically applied by vacuum deposition . A protective overcoat is usually applied before the mirror is removed from the vacuum, because the coating otherwise begins to corrode as soon as it is exposed to oxygen and humidity in the air. Front silvered mirrors have to be resurfaced occasionally to keep their quality. There are optical mirrors such as mangin mirrors that are second surface mirrors (reflective coating on the rear surface) as part of their optical designs, usually to correct optical aberrations .