Celestron C8 or C9.25

[David JM]

*cough*

http://starizona.com/acb/HyperStar-3-Lens---925-Celestron-P3206C773.aspx

James

I was going on this "The 9.25-inch optrics are not compatible with Starizona's Hyperstar but Celestron's f/6.3 focal reducer can be used." from a non-FLO shop, it says on the link you give:

"What telescopes are compatible?

Only new, factory-equipped Fastar-compatible 9.25" SCT telescopes have a removable secondary mirror assembly, allowing the use of the HyperStar C9.25 lens. Older 9.25" SCTs are NOT compatible, nor can they be converted."

So I would guess that the C9.25 is the non removable sort.

[David JM]

Your supposed to be helping by bank account !!!

Buying kit is a sin. Give your money to me and I will save your soul by purchasing kit and creating a shortage so that others be not tempted by worship of the night sky [and the sun with a solar filter].

I will be tarnishing my soul, but if everyone gives their scope money to me they will not be swearing at the clouds any more and will live happier lives. And you can spend any remaining money on After 8s

To donate call 1-800-give-me-your-scope-cash...

[JamesF]

I was going on this "The 9.25-inch optrics are not compatible with Starizona's Hyperstar but Celestron's f/6.3 focal reducer can be used." from a non-FLO shop, it says on the link you give:

"What telescopes are compatible?

Only new, factory-equipped Fastar-compatible 9.25" SCT telescopes have a removable secondary mirror assembly, allowing the use of the HyperStar C9.25 lens. Older 9.25" SCTs are NOT compatible, nor can they be converted."

So I would guess that the C9.25 is the non removable sort.

My understanding is thus:

All Fastar C9.25s are compatible. For pre-Fastar models, some of the Celestron SCT models have a conversion kit that allows the secondary to be removed and the Hyperstar to be fitted. There is no kit available for the non-Fastar C9.25 however.

To the best of my knowledge, all current models from the C6 up are Fastar-compatible so if you're buying new it wouldn't be an issue. If you were buying second-hand and specifically wanted to be able to use something like the Hyperstar camera then you'd need to check.

James

[asteele3]

I got my c8 and Heq5 yesterday. If you're not planning on taking the scope anywhere then the 9.25 might be better but for the sake of saving a few hundred quid then I'd get the c8 based on the weight as it's so much lighter than the 9.25!

[ollypenrice]

The Hyperstar isn't a 'bit' faster than the fastest refractor, it is nearly 4 times as fast!

The diffraction issue can be tackled in one or maybe two ways. Greg Parker made a cross of (I think) cable ties so that three unecessary spikes are created to match the one created by the cables. I asked if he thought that routing the cables in a curve would kill the spike and he thought it probably would. If you then moved it sometimes between frames I suspect the aretfacts would vanish under Sigma. With lots of short F2 exposures Sigma is going to be powerful.

I'm not really advocating the Hyperstar. I can see the attraction and I've seen good results. However, if I were to buy an F2 system I'd like to buy one designed and engineered from the ground up and fitted with a focuser that was intended to handle a micron-thin focal plane. My fear would be that fettling would eat into imaging time.

Olly

[peteftm]

Back to the mount , if you do away with the tripod and use a steel pier that would sturdy things up a bit.If it is planetary imaging your wanting to do then i'd go for the C9.25

[asteele3]

I ditto what peter said.

Of course for planetary imaging I'd get the best scope available 14'' would be good but most of us can't afford it!

The 8'' is a good scope, nice size and more portable. If you got the 9.25 and the Heq5 then be willing to spend £2,000. Whereas the c8 and the Heq5 would knock that down to £1,600.

[JamesF]

It has been said that the C11 and C14 are only really better than the C9.25 when the seeing is absolutely perfect. What counts as "best" in this case might therefore not mean "what has the largest aperture", though I imagine living up a mountain in Hawaii might help

James

[Viv]

Guys - thank you all.

So much to think about & consider, think the Hyperstar is completely out of the question for now.

Would rather be investing in a permanent base, so I can keep the imaging going overnight.

Then see what it gives.

[x6gas]

It has been said that the C11 and C14 are only really better than the C9.25 when the seeing is absolutely perfect. What counts as "best" in this case might therefore not mean "what has the largest aperture", though I imagine living up a mountain in Hawaii might help

James

Plenty of people get better planetary imaging results with their C9.25s than I've got (so far) with my HD11, but that's mostly down to the skills of the person rather than the kit!

Interesting that the 9.25 is reckoned to be more tolerant of collimation errors by virtue of the less demanding focal ratio of the secondary...