RE: [APML] OT: AP Oil Spaced Lenses

["John Gleason" <dvj@earthlink.net>]

Chuck, 

My 7" f/7 is gel spaced not oil spaced. The gel used is from the fiber
optics industry.  I can see changes in the gel when there is thermal shock
to the cell during cool down.  The cell is sealed, but there does not
appear to be a manifold to compensate for contraction or expansion of the
lens elements.  Roland told me so.  The 6" f/7.1 that I also own (7 years
old) is oil spaced as per Roland.  This appears in early 90's AP
literature. 

jg




> [Original Message]
> From: Chuck Vaughn <aa6g@aa6g.org>
> To: <astro-photo@seds.org>
> Date: 6/21/00 9:53:26 AM
> Subject: [APML] OT: AP Oil Spaced Lenses
>
> Hi List,
> 
> Several times it has been mentioned that Astro Physics is using oil
> spaced lenses in the current telescopes. In a recent private conversation
> I've had reason to question this. I have not seen anything on AP's web
page
> saying they do this. It's also been pointed out to me that oil spacing
would 
> require a seal to keep the oil from leaking. There's no evidence of seals
> in AP lens cells. So my question is this: Does anyone have first-hand
> knowledge that AP is oil spacing their lenses? In other words, has Roland
> told you so in a private conversation, has he put it in print somewhere
> or have you disassembled a lens and found it to be oil spaced?
> 
> Thanks,
> 
> Chuck <aa6g@aa6g.org>
> 
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--- John Gleason
--- dvj@earthlink.net
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