A little while ago I purchased an AE 12" F:5/20 Cassegrain telescope with an 3" diameter secondary mirror which I plan to use for lunar and planetary imaging.
The owner sold it in the Newtonian mode and had forgotten the primary-secondary optimum mirror separation for this particular telescope.
I plan to renovate the OTA by using carbon fiber tubes to replace the original 6 aluminum tubes that form the skeleton OTA. Also I will add a modern focuser.
Does any member still have a similar telescope or can recall the mirror separations?
I have contacted Martin Mobberley who once had a 14" similar telescope. However, the separation came already set upon delivery and needed no additional thought.
As Martin suggested I could plate solve images to determine the plate scale making any necessary adjustments until I obtain the expected F:20 focal length.
Hopefully, any owners past or present may already have the information to give me a head start.
Best wishes,
Eric
Hi,
with further assistance from Martin and ES Reid ( maker of mirrors for AE) together with using the Cassegrain equations and comparing to the existing Newtonian set up the problem has been resolved. Answer being 45" with a little tweaking when compared to images if necessary.
Thanks if you took some time to give this your attention.
regards,
Eric
Sounds a really interesting and worthwhile project, Eric. I hope you'll document it and share how you get on with members.
Good luck!
Jeremy