Re: [APML] co-efficient of expansion for 10" SCT

[Duncan Munro <dmunro@sfu.ca>]

Alan , thanks. Doc G and Michael Hart measured a focus change of  .15mm 
per .6deg C. with an 10" F10 OTA, so this is about the same as my 
results when you consider the reduced magnifcation factor of the f6.3 OTA.


cheers

Duncan

Alan Voetsch wrote:

>Hey Duncan,
>
> Doc G. is probably the guy most likely to have done this. You could
>try posting your question on MAPUG to see if he, or someone else has an
>answer for you. I do remember that he had even gone as far as measuring
>contraction/expansion OTA potentials from the nearby heat of a human
>body on a cold night.
>
>Alan
>
>--- Duncan Munro <dmunro@sfu.ca> wrote:
>  
>
>>Has anyone calculated the co-efficient of expansion for a 10" SCT?   
>>I've done some rough  testing with my 10" F6.3 OTA and I'm getting
>>about 
>>.15mm per deg C.  Does this sound plausible?
>>    
>>
>
>
>
>SCT Astrophotography: http://www.pbase.com/avoetsch/astrophotography
>FS-102 G-11/Gemini: http://www.pbase.com/avoetsch12952/tak_fs102
>& http://www.pbase.com/avoetsch12952/fs102
>& http://www.pbase.com/avoetsch12952/takpf
>
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