Re:better explanation (Score 1)

Actually, that's not true.. That's the whole point of those.. well, definately not ht whole point.. but a big one.. the lenses cost thousands, if not millions, to manufacture.. they have to be essentially FLAWLESS.. They also must not be affected by unavoidable effects such as gravity... when you're talking about nanometers, the bow on the lens caused by gravity is very large.