GSO 10" RC white or carbon fibre?????

[clive milne]

If it was my money, the priority would be for an ascom compliant focuser.

[brian nordstrom (As avatar)]

Originally Posted by Adsyadsman

This is a very interesting thread as I've been asking myself the same question - steel vs cf?
So the consensus is cf is better for less thermal expansion, but in the real world environment, say if I was to leave the scope outside for a couple of hours before use to equalise with the ambient temperature, and considering the temperature during the night hours will only drop say 10 degrees max, what effect would this have on the focus of a steel vs cf scope? Would it really throw out focus that much? And if so, even with a cf tube, would you still need to tweak the focus slightly anyway?
Reason Im asking is, if you still need to tweak the focus of a scope with cf tube, even though its less, wouldn't getting a cheaper steel tube kit with motor focus be a better option as then you could almost guarantee (electronic/software glitches aside) your imaging session would be more hassle free?

Just to add, I was thinking of a fast scope like a f4 newt that I understand would exacerbate the issue. I'll start another thread on this, but wanted to ask anyones real life experiences with the GSO f4 8" cf newt vs the SW twin.

Just my boggle?

Thanks also to all you experienced and knowledgeable bunch out there for sharing your wealth of wisdom with us, really helps to enjoy astronomy further.

That may be true in Adelaide where you live (10 degree temp change ) but what about the people living in Tassie or the bottom of the south island of NZ ? 10 degrees is nothing to them , more like 20 ?
CF is the material of choice for most , f they can afford the extra$$$ .
Brian.

[Paul Haese]

Just going off my own experience with the GSO RC8, cooling is fast and focus is well held. I found that I only had to refocus every 4 hours of so when imaging with that scope. With the RC12 I have had to refocus every 40 minutes or less to maintain good focus.

[clive milne]

Originally Posted by Adsyadsman

Just to add, I was thinking of a fast scope like a f4 newt that I understand would exacerbate the issue.

Whilst it is true that fast telescopes are more sensitive to focus position, it is also true that fast instruments have shorter tubes with less focus drift due to thermal expansion.

[Marke (Mark)]

With the $700 difference i paid i got a feathertouch with temp compensation focus control

[Adsyadsman (Adam)]

Thanks for you input guys.
Paul, your RC's, were they the alum tubes or CF's?

[Capricorn1(Tom)]

Irespective of the expansion rates of the different materials, you will be fixed by the losmandy plates top and bottom. Would agree if the materials were similar that is the plates were CF, top and bottom.
I think its a marketing ploy----the only advantage is the weight component.

[MrB (Simon)]

Originally Posted by Capricorn1(Tom)

----the only advantage is the weight component.

... and it looks mint

[Adsyadsman (Adam)]

Good points about the mounting plates.
I guess if you wanted a steel tube to look as schmick you could wrap it with cf vinyl wrap or even a custom paint job some flames or a GT stripe?

But seriously, if you guys with cf tubes ar still needing to tweak focus slightly thoughout the night albeit only once or twice, maybe saving coin on a steel tube being spent on a robofocuser might be a viable alternative

But, from what I've read, looks like most steel tubes, especially for DSO imaging still needs some reinforcing around the focuser due to image train weights affecting collimation...

[allan gould]

Originally Posted by Adsyadsman

Good points about the mounting plates.

But, from what I've read, looks like most steel tubes, especially for DSO imaging still needs some reinforcing around the focuser due to image train weights affecting collimation...

this point was made in post #8 and re-inforcing has never been done on GSO RC. I think you are confusing this with those that have Newtonian scopes and since their focusers are off axis they need reinforcing due to lateral stresses.

Depending on the temperature drops during the night my Metal tube 10" GSO RC only needs one tweak generally an hour after starting imaging and I bet thAts about par for the CF tubes as well. I spent my money on a better focuser.

[Adsyadsman (Adam)]

Originally Posted by Paul Haese

Just going off my own experience with the GSO RC8, cooling is fast and focus is well held. I found that I only had to refocus every 4 hours of so when imaging with that scope. With the RC12 I have had to refocus every 40 minutes or less to maintain good focus.

Originally Posted by allan gould

this point was made in post #8 and re-inforcing has never been done on GSO RC. I think you are confusing this with those that have Newtonian scopes and since their focusers are off axis they need reinforcing due to lateral stresses.

Depending on the temperature drops during the night my Metal tube 10" GSO RC only needs one tweak generally an hour after starting imaging and I bet thAts about par for the CF tubes as well. I spent my money on a better focuser.

Sorry Allan, I was referring to newt scopes requiring reinforcing due to the focuser hanging off the side of the tube. My bad