7189Re: [William-Optics] Re: Air-spaced versus oil-spaced lens elements?
- Jan 23, 2006The lens designer I know uses a synthetic oil with a refractive index carefully matched to the glass. Protected from oxygen between the glass elements he doesn't think that deterioration over time is much of a problem. But even if after half a century an oil-spaced lens needed servicing it seems like a good compromise to me. Another myth is that they'll leak oil. Truth is that the cohesion forces of such a thin film of oil prevent this from happening even under pressure. Sealing the edges is largely unnecesary but they do it anyway. Is your f/15 a nice achromat? I'd relish a look through it.......
Rick Jack <jack11973@...> wrote:Hi,How does the oil hold up to time and elements? I know some oils used in microscope optics discolor and reduce light transmission. I've been using a 6" f15 air spaced objective for years without a hitch.Regards,Rick
Robin Retzlaff <robinretzlaff@...> wrote:Glad to help. Hopefully we'll get opinions from others and mix it up a bit.
rfrisk <rfrisk@...> wrote:
Great Scott, Robin - you just addressed about 99% of my questions in
one post!! My reason for purchasing this scope is casual planetary
observation and serious DSO observation and imaging. I have been
strongly favoring the WO FLT-110 and appreciate the heads up for
Tom's review. I really appreciate you taking the time to reply with
such an informative response. It helped me out more than you know.
--- In William-Optics@yahoogroups.com, Robin Retzlaff
> We could try and start a discussion of this issue here if you
want. FWIW I'll share with you some of my gleanings and hope for
someone more knowledgeable to post........
>The curvature radiuses of the mating surfaces in an oil-spaced
design must be .....
>The main thermal problem with air-spaced lenses are the .....
>The amazing Flt-110, by the way has all the advantages of an oil-
spaced design and with its......
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