Quote:
Originally Posted by Ukastronomer
I use a Quark on the triplet and you do not need a filter on the front of the scope at 120mm, you are told to with oil due to heat
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That’s news to me - a telescope’s lens getting hot when exposed to the sun (not talking mirrors here).
Apart from Roland, Yuri, CFF also
Baader claims that oil-spaced lenses are great for solar observations/imaging:
[oil-spaced lenses] are great for observing the sun – even and especially with our Cool Ceramic Herschel Wedge. The oil doesn't suffer or deteriorate under long usage (UV-radiation). We do not use a classical "oil". Carl Zeiss invested a decade of research into the development of the fluid which is used for these lenses today – and they gave a 30-year-warranty, which is now fulfilled by us.
Apologies for getting off the topic
