|Quoting megatop412 (Reply 4):|
Charlie I think those are 'mirror' lenses, I think I read that they basically need an incredible amount of light to deliver decent images. Not sure about the sharpness but pretty sure not sharp enough for here
Nope; Not mirror lenses at all; I haven't played with telescopes all my life not to know the difference between mirror lens and an ordinary refracting lens; what they are are is elcheapo junquo, made in Madagascar by termites, in the hope that if they advertise them enough, some poor kid that doesn't know any better will waste his money and buy one.
Not that the old mirror lenses were very much better; using mirrors works just fine on astronomical telescopes, but telescopes have a completely different job to do, from camera lenses. They found out over a hundred years ago that when you reached 36 to 40 inches of aperture, that it was as big as you could go with a refracting telescope; since that time, the technology involved in mirror making has allowed reflecting telescopes to just keep on getting bigger and bigger.
Mirror lenses for cameras are completely impractical for a whole bunch of reasons; you have no way of controlling the aperture for one thing; the only way you can control exposure is by varying the shutter speed; it spite of all of their inherent problems, Nikon dabbled around with them for years and never made enough to cover all of their R&D expenses.
Almost all young kids get interested in telescopes at a very early age, so even reputable telescope makers like Meade and Celestron build a "beginners" line of 3" and 4 inch scopes that aren't worth bringing home; in the meantime, thousands of young kids buy this crap, never get enough performance out of it to even satisfy a kid, so they end up getting discouraged, deciding that astronomy is "for the birds", which is really sad. A few years back, eBay was a great place to buy stuff, and also to get rid of stuff; it still is up to a point, but over the last 3 or 4 years, it's become a haven for shysters selling cheapo junk from the third world, and you can't find anything any more for all of their cheapo advertising.