Looking at the difference in thermal expansion, even if you have two dirty big dove tails top and bottom, you will see the expansion. Even at 1200mm my skywatcher expands in what terms i cannot tell you exactly but it brings my fwhm from say 2.5 up to 3.5 over the span of a hour and a half, now i can tell you that is a big difference in clarity.
CF tubes are generally a lot lighter even with the epoxy resin and differential materials.
Good imaging practice you should be assessing your focus every hour or so, now with auto focusing this is very easy to do, you don't even have to slew off to a different part of the sky. Though everybody has their own way at the end of the night.
Oops !
Thanks - Yes, you're correct, its about 0.3mm thats a bit bigger !
300 microns is going to put most scopes out of their CFZ !
Messed up my microns to mm instead of m conversion !
There is still a need for paper sometimes - it leaves a nice audit trail of your mental process that a PC calculator doesnt !
However I think that with focussing between subs or filter changes this should be the least of the GSO problems.
Mind you some of the other firms are producing tubes in aluminum. deep sky instruments being one I can find, but only for 10" scopes. Time will tell though.
Gday Paul,
The DSI 10" scopes are definatly not made from aluminum, the OTA's are a phenolic tube. My old 10" GSO Aluminum scope was a real pain with the shifting temps here in perth (and hence it took some effort to keep focus) without the use of electronic focusing capabilities.
Allan, you can give it a try I suppose but be mindful of the wind factor. This is way longer than an SCT of similar size. It is actually a bit longer than the C14. That makes for a longer lever arm and hence the concern. It might be a good excuse to upgrade the mount.
Paul
I'm now in a quandary as I've weighed the Meade 10" SCT, guided scope camera etc and at the moment it comes in at 26 kg on the Losmandy mount. This is with the metal dew shield and the length and diameter are close to the 12" GSO RC that you have, but obviously a little smaller.
All this is in the observatory and thus shielded from wind etc (Sirius dome). At the moment I'm guiding at a FL of 2500 mm with absolutely no motor stalls or strain on the mount when slewing.
At 22kg for the GSO RC I'm thinking I might be ale to get away with it but seriously it would only remain as an observatory scope. I'll be interested to see how things go and your experiences.
Allan
Allan, if you want one just get it. Mike Sidonio is riding that monster on his NJP so just give it a shot and if it does not work either buy a new mount or sell the scope.
Just investigating some flex of the rear assembly at present. Might be some loose screws but when I slew the scope and look through a cats eye collimating cheshire I see some flex in the reflections. The center spot might not be correct either but I am just going to investigate this a bit better. More later.
This will eb an intersting thread...good luck Paul, if it's any where as good as the RC8, it should be a good scope. Well done on getting the financial support too
Allan, if you want one just get it. Mike Sidonio is riding that monster on his NJP so just give it a shot and if it does not work either buy a new mount or sell the scope.
The NJP is no G11 it is a very capable solid mount considerably ahead of it's specs even. I have it loaded up to the hilt and it just ploughs along like an exocet missile ...not sure if the G11 could handle what I have on the NJP
Who knows mike the G11 isn't a slouch either some would say the same about a puny EQ6... but its happily trudging along with 24kgs plopped up on top with the CW to boot. Good luck with the 12" Paul, Aperture is definitely a boon and well worth the effort.
Thanks for that. I wonder if he'll make a custom reducer for the CDK with less backfocus requirements.
The ASA letterhead doesn't inspire confidence although as far as I know Phillip Keller does quality gear.
I imagine it is also a very expensive corrector. I didn't see any mention of price - very European, but I would estimate
US$1200 to US$2,000. A bit much for a AUD$3500 scope. I wonder if a simple Tak 4 inch flattener would work. As far as I can tell
scopes don't seem to be too fussy with flatteners and much more fussy about reducers.
I'll be trying the Tak flattener anyway, since it work pretty well with the RC8". Yes I would not be spending 1200 on a flattener, and certainly not on something that costs twice that amount.
For anyone reading this after the fact this thread won't make much sense now. This is what was said before they both edited thier posts:
Quote:
Thats for Newts James. Although I think Keller does make flatteners for RCs on order.
Greg.
Quote:
I'll be trying the Tak flattener anyway, since it work pretty well with the RC8". Yes I would not be spending 1200 on a flattener, much less a reducer.
I'll be trying the Tak flattener anyway, since it work pretty well with the RC8". Yes I would not be spending 1200 on a flattener, and certainly not on something that costs twice that amount.
That's probably about the price it is. You wouldn't buy it for something like an RC8 or even a RC12, but if you had a much larger scope that made the purchasing of such a flattener economical and it was designed for your scope, I suppose you'd fork out for it.
Forking out $1200 or more for a flattener to fit a $2000-$3000 scope is a bit much
Original version:
"Yes I would not be spending 1200 on a flattener, much less a reducer."
New Version:
"Yes I would not be spending 1200 on a flattener, and certainly not on something that costs twice that amount. "
