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Message: <blockquote data-quote="Binastro" data-source="post: 3477238" data-attributes="member: 111403">Thank you very much for the interesting information, maico.I was offered 6 Zoomar 180mm f/1.3 motion picture lenses at about £650 a time many years ago.I wasn't interested in even one.But he had an incomplete one at £25 in its trunk, which I bought.I managed to get all sorts of adaptors from someone else for next to nothing for Contarex etc etc and Minolta.I put it on my Minolta and although the ring was missing I could operate it with say a pencil.Although it was a half frame 35mm camera lens, it worked absolutely fine at full aperture. The field was curved, but flat on half frame or movie format. On full frame 35mm the edges were soft but most of centre sharp at f/1.3.It was fast, although I can't say it was easy to hand hold. I usually balanced it on something.The seller was not happy when I showed him the photos I took with what he thought was a non functioning lens.They also made a 240mm f/1.2 Zoomar/Kilfitt, I think, for medium format. It is big.There were Kilfitt adaptors I think for all sorts of movie and film cameras.I have, though, seen much bigger lenses such as 14 inch f/0.75 weighing I think 350 lbs. Mounted on a truck.The top makers have developed strategies for using Calcium fluorite, probably by coating straight away, although coating is probably very difficult in this case. Then sealing the element in so no moisture gets in.By controlling things carefully they probably don't get many failures now, although they probably did early on.I would not choose a crystal lens scope if I was in a tropical jungle environment. Eventually nature has its way and moisture gets in.But I take the point that most Kowa scopes are fine, although I suppose any problems are immediately dealt with by Kowa, a top maker of exotic optics.P.S.I think the calcium fluorite has problems with laser light and deep UV, but I don't know the details.Quartz is used in things like some of the Questars, I think.P.P.S.Those early Canon 300mm f/2.8 were often sold off at £100 or less because of the serious degradation of the calcium fluorite element.</blockquote>

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