Dear Frank,
The exact focal length with the "standard" Meade or Celestron "f.6.3" focal reducers, is 2,370mm. This is taken from using the standard Celestron 1.25" visual back. The resulting f/ratio is f/6.88. However, the FURTHER you are back from the focal reducer, the longer the focal length (and the more coma being introduced) but they are less senstive to distance than the Optec focal reducers and this is why we prefer them. We have run our C14 with filter wheels and flip mirrors using them up to f/7.2, without any problems with CCD chip sizes up to a ST-10.
Trust this helps you.
If you have any Celeston C14 questions, please feel free to ask me - Grove Creek has the 2nd C14 ever made by Celestron and it has undergone a lot of modifications and different configirations. We have a movie on YouTube about our C14. Just go to
www.youtube.com and search for "C14 Grove Creek". More details about our C14 is at:
www.gco.org.au/scopes/
Our C14 has recently been moved out of our fork mount to a Astro-Physics GTO-1200 mount. The previous fork mount had a Agro Navis and DEC & RA stepping motor tracking system that I built and designed. The fork, motors, controller, Agro Navis and encoders are now all packed away, where we may possibly sell it in the future. The fork only had a PEC of 9.75^sec peak-to-peak, which was very good for its time - 1972.
Steven Williams,
Managing Astronomer
Grove Creek Observatory
www.gco.org.au
Quote:
I still don't know what I should say about the focal length: The C14 is an F11 so when I put the the 6.3 focal reducer on does it make it 6.3 or 7.3 ?
????
anyways,
i've had a quick try of 1 min shots at F11 and cant wait to try that seriously, that'll be a focal length of 3.5 meters and promises to reveal nice stuff a few small and fuzzies I want to image
gotta work out balancing/guiding etc first
i'll keep everyone posted
cheers
frank
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