I'd like to learn more about this, I was laying in bed last night thinking of how a telescope lens is made......how long it takes, the polishing and stuff....What about cameras? And why are some like say a Carl Zeiss lens that Sony touts so good, etc.?

Wow.. so many factors, so much math.. grin I've taken about 3 optics classes and still couldn't tell you anything very specific about lens-making.. I've mostly learned the theory and math behind how they work. So, basics: lenses can be made with pretty much any refractive material (it's why a round bowl filled with water can be a fire hazard if it's in direct sunlight or why your eyes work when they're 90% water). From what I know from school though, most lenses are made from glass materials with formulas specific to the manufacturer. The reason because glass is mostly predictable as far as structure goes during manufacture (although a chemist would be able to tell you more about this - I only took as far as basic organic chemistry, myself). Polishing, from the little "field trip" we took to the National Research Centre back in college, seemed to be mostly made with sandblasting and water (for large mirrors and lenses) all the way down to very fine, high-power lasers (for very small pieces, i.e. fiber optics systems). Lasers in general are used to measure the lenses' properties, at least on the prototype, too. As to why some are better than others.. I'd say that most of the time it's because they're better suited for the job than others. While one lens may have less physical aberration (shape 'interference'), it might have more chromatic aberrations (color 'interference'), etc etc. So one lens for regular camera use might be excellent over another that sucks, while the situation is the exact opposite for, say, communications (shape reproduction is highly important in the former, while the latter might be more interested in the duration of the pulse of light itself). The whole manufacturing process is also a big factor, and the batch itself (you can get lemons in anything). Also, experience from the manufacturer helps a lot (math only takes you so far - the physical world tends to be quite different). So, anyway, I'm probably useless to you, but your post seemed lonely. :) - darkpen

Thanks, darkpen. Learned a lot about lenses, and something more about you, from your post.

It just struck me when I woke up this morning - if you really want to know more, you should ask in the sci.physics.optics newsgroup. A lot of the people who hang out on those sci.* are chemists and physicists, and you might even find someone who works (or studies) specifically in lenses. Even amateur astronomy newsgroups might be of help, too, as some of them make their own telescopes from custom mirrors and lenses. - darkpen

Hi all, I assume that astronomers just buy the best lenses or what ever is the best they can afford. Makeing mirrors is a thing of material science perhaps a materials engineer. Although I do know a classmate which later worked at Corning in NY. I'm sure she studied glass. So she should know something. Basically polishing a mirror and I assume a glass lense to get it right is a work of art and is in general a real big time drag!!! It's why Johan Keppler put up with Tycho Brach. Anyone who has polished silverware knows that there are better things to do. If you have ever polished plastic you have an even better idea. Now imagine doing that to a hard material like glass AND be precise while you are at it. Carl Zeiss lenses are supposedly hot stuff. I've read that some nice camera manufacturors use the Zeiss lense. Plus it's Swiss so it's gotta be good right!! I think the one Sony camera with the huge ( 4 inch ) lense is alright optically but the others...I'm not to sure. My personal experience is that my Kodak point and shoot is in focus more often than the Sony. BUT my Sony does not have a Carl Zeiss lense. ( IT also has a 10X zoom ) So if I take the manual picture right I should be happy. Darkpen-Yeah optics courses in physics I don't think will teach you about making lenses. Unless lense manufacture is performed in the lab Glass structure really was not covered in my chemistry courses and I have about five years worth of chemistry. Glass is mentioned a tad in the first year, second year, and final year. Mostly because it is a crystaline, slow moving liquid, has pores, and also a means to an end. But I polished plenty of plastic smooth in a design and industry course about plastics!!!! Does that count? SYYD-I think though that the factories have figured all that kind of stuff out already so lense making occurs pretty quick. There's probably some automated lense polisher thingie out there which does itall automatically. BUT if you really want to try it out on your own I have some plastic polishing grit paste and ultra fine ( 2000 grits per inch ) sand papaer I can mail to you!!!! Or you can probably use a nail polising, buffing, board. Bsteph

Hey, polishing plastic by hand is a feat in itself (at the very least in patience! :P), so you get extra points for that. :) - darkpen