[PlanetMan]

Lewis

If the "old" refractor you mention is the Fluorite lens refractor you were thinking of buying in another thread DO NOT touch it but seek some professional advice.

Some time ago I was thinking of buying a genuine fluorite which had what appeared to be a "dirty" lens. I sought advice from several sources and you have to be very careful. Firstly, Bintel for example, will not clean any fluorite lens due to what they describe as 'risks' with such lens. Instead, they recommended a highly specialised camera repair store in the middle of Sydney (one of the remaining few) which largely only repairs and cleans cameras. Apparently, there is a very particular and apparently expensive fluid which is safe for use on fluorite crystal. I also consulted AstroOptical and they also mentioned that some problems/degrading can arise with fluorite lens which they described to me as a "cloudy" appearance in the glass. I haven't seen what this is supposed to look like for myself but if I can offer you a little advice from my own experience - if your refractor is an original fluorite crystal lens take it to a specialist optical repair store that works with fluorite lens/optics. Fluorite is apparently much better than standard ED glass but also requires a lot more care and is comparatively more perishable.