Celestron 9.25

[Brinders]

Hi guys. It looks as though I'll be able to to get my dream scope in the New Year to supplement (not replace) my trusty old TAL 150P. After much soul searching, reading reviews and various forums (including good old SGL) I've decided it's got to be the Celestron 9.25, probably on the Skywatcher HEQ5 Pro mount. It will have to be stored in the garage so temperature difference from storeage to setting up outside shouldn't be too different, which leads me to ask - the carbon fibre tube or the aluminium one?

I'm hoping to do some astro photography eventually and I believe from FLO's site that the carbon fibre OTA will be more rigid and suited to astro photography but has a longer cool down time. As I say, as the OTA will be kept in the garage, I don't think that cool down time will be too much of an issue. However, looking at Celestron's catalogue, I believe the carbon fibre tube comes with a CGE/Losmandy dovetail, while the aluminium tube has the CG5/Vixen/Skywatcher dovetail. Does that mean the carbon fibre tube won't fit the Skywatcher HEQ5 Pro or will I have to buy another dovetail and if so how easy is it to fix to the tube and remove the CGE dovetail? Advise, please.

[Whippy]

I reckon your best bet would be to phone and check. I would imagine you'd be able to get either dovetail on either tube material. Carbon Fibre would be better as it's sexier and therefore better . Seriously though, I don't honestly know what the difference would be.

One thing though, you may want to consider an EQ6 for the mount as you may want to do autoguiding with your imaging gear at some point and a HEQ5 may not like all the extra weight.

Tony..

[cygnusx1]

I have a C9.25 + 66mm APO + DSLR + 2" diagonal with MEade DSI totalling close on 14kg on a side by side plate running fine on my HEQ5 Pro for imaging.

The mount is rated at 10-15 kg so i am pushing its limits esp for imaging, but i've had no problems after proper balancing and counterweighting.

If you don't/can't spend the additional £200 on the EQ6 Pro it'll do fine.

As far as which to use as guide or imager, that depends on what you want to image in terms of fov.

For autoguiding, i would say don;t use a guide f/l shorter than 1.5 -2 times the image scope f/l.

Here's a good autoguide primer i posted > http://stargazerslounge.com/index.php/topic,20532.0.html

Ian King Imaging sells a solid dula mount plate for about £120 incl postage.

HTH

[winfij]

I'm hoping to do some astro photography eventually and I believe from FLO's site that the carbon fibre OTA will be more rigid and suited to astro photography but has a longer cool down time. As I say, as the OTA will be kept in the garage, I don't think that cool down time will be too much of an issue.

The CF OTA has a higher thermal stability - it doesn't expand/contract as much with temperature changes.

This should mean that if you do high-res imaging then the focus shouldn't shift as the temp drops throughout the night, requiring less refocusing.

John

[MartinB]

The 9.25 is a mighty scope. Think seriously about the focal length of the scope - the long f/l is a major challenge for imaging and most people with SCTs use focal reducers. These are great but can cause problems with vignetting and distortion of stars at the edge of the field of view with large chip cameras such as DSLRs. Wonderful, versatile scope though

For autoguiding, i would say don;t use a guide f/l shorter than 1.5 -2 times the image scope f/l.

Actually you can go a lot shorter than that. With my ZS66 (400mm) I'm getting RMS tracking errors in RA or around 0.05 pixels. That equates around 0.4 arc seconds with my guide camera. This will therefore be able to guide a 2500mm f/l 10"LX200R without any problem. The guy who wrote the excellent article you posted is actually guiding a 2575mm scope with a 213mm guider!

[winfij]

Actually you can go a lot shorter than that. With my ZS66 (400mm) I'm getting RMS tracking errors in RA or around 0.05 pixels. That equates around 0.4 arc seconds with my guide camera. This will therefore be able to guide a 2500mm f/l 10"LX200R without any problem. The guy who wrote the excellent article you posted is actually guiding a 2575mm scope with a 213mm guider!

Absolutely - I guide my 10" LX200R (fl = 2670mm) with my SDHF-75 (fl = 500mm) and get nice round stars.

John

[cygnusx1]

Martin/ John

I guess what i meant to imply is that it depends on the resolution of your guide ccd and image equip, along with the focal length of the 2 scopes.

For example trying to get accurate guiding with my A.C9.25 + dslr with my B.66mm APO + Mead DSI is almost impossible.

The resolution of A = 0.89 arcsec/pix and B. 4.5 arcsecs/pix so by the time B observes an adjustment, A has already moved 4x as much!

edit: ive just reread his setup, hes guiding @ 7 arcsec/pix to a 0.7 arcsec/pic imager????

ok now im totally confused

[Andrew*]

Sorry guys, but this is really for a different thread.

Brinders never even touched upon the subject of autoguiding. Please keep on topic

Cheers

Andrew

[Brinders]

Thanks for the advice fellas, but the EQ6 Pro mount is out of the question. I'll be pushing myself to afford the EQ5 Pro, which from what I've read previously, is a far better mount than Celestron's own CG-5 GOTO which was the one I originally considered (and I note some guy in OZ has used successfully for deep sky imaging despite the received wisdom to the contrary). Also I hear the EQ6 is a bit of a beast weight wise - I will have to shift it from garage to garden after all and I may want to try transporting scope and mount to a dark sky location from time to time, so the EQ5 Pro it has got to be!

As to auto guiding, well that's something for the future but no doubt I'll give it a go.

I'll give FLO a bell when I'm ready to order and seek their advice about the dovetail.

Sincerely, thanks again for the advice guys and a Merry Christmas to you all.

[Whippy]

Well, whatever route you choose let us know how you get on eh?

Have a good one over the festive period!

Tony..

[jcm]

I have been considering a C9.25 or 10" Meade.

If I was getting either I would save up for the EQ6 ( mounted in obs). The HEQ5 I use at the moment can handle my present set up ( 10kg max) and produce good images - I do not think this would be the case if I went above this weight. I suppose the big advantage of the HEQ5 is its just about moveable but the EQ6 is not. My present telescope is F6 so guiding with the HEQ5 is fairly easy but putting an F10 SCT on it would make accurate guiding difficult.

PS - The HEQ5 is an ideal mount for star parties.

John

[The Warthog]

OK, here's a consideration. In Canada, If I buy the C9.25 OTA, it costs $1530, and the EQ6 costs $1499. Add taxes, and the grand total is $3456. If I buy a C9.25 on a CG5, because of the bundling practices of Celestron, the whole dog costs me $1,999, or $2,279 with taxes, for a grand savings of $1,177. This looks like a mighty powerful reason to go with the Celestron mount. Isn't it?

[MikeP]

I bought a C11 on a CG5 this year and it cost hundreds of pounds less that buying the C11 as an OTA alone. David Hinds assured me that was Celestron's policy, so I happily bought the combo and sold the CG5. I don't know if this pricing is still applicable here in the UK.

Mike

[barkis]

I have no business spending your money for you WH. but based on all the positive vibes I have been receiving from owners of the EQ6 mount, If I were starting again from base level, I would make my first purchase that mount. I would be satisfied using it to image with a camera lens of whatever size I had, until I had raked enough pennies together to buy an OTA befitting it's capability.

I don't really know if imaging has any role to play in your future plans, if not please ignore all I have said.

Ron.

[The Warthog]

I bought a C11 on a CG5 this year and it cost hundreds of pounds less that buying the C11 as an OTA alone. David Hinds assured me that was Celestron's policy, so I happily bought the combo and sold the CG5. I don't know if this pricing is still applicable here in the UK.

Mike

Yep, in the interim, before I retire, I have considerred buying the C6N on a CG-5, which costs less than the CG-5 alone, and selling my present C6N and keeping the new one. Then I will have a CG-5, and the option of buying the OTA for the 9.25, and having a versatile collection of gear.

[jcm]

Just had a look at the weight of the c9.25. I recon for observing and a bit of imaging a well balanced C9.25 on an HEQ5 would be OK. If you are going detailed astro imaging then the EQ6 is the best option.

John

[The Warthog]

Is the CG5 more nearly equivalent to the EQ5, or the HEQ5?

[Andrew*]

the CG5 is virtually identical to the EQ5. I believe there are some internal improvements though, and it comes with 2" thick legs as opposed to 1.5"...

[Brinders]

Hello again fellas, seems I've started something here. You are all giving me the same arguments and counterarguments I've been debating in my own head for the past couple of months.

I've read the Sky at Night Magazine group test of mounts from their July 2006 issue, I've also trawled the forums which appear to largely come to the same concensus as Sky at Night Magazine: the Celestron CG5 while on thicker (2 inch) tripod legs than the HEQ5 Pro (1 1/2 inches) is actually a less sturdy mount. This is because the Skywatcher mount is 4 kilos heavier and the actual mount is more substantial. The Celestron computer has the advantage of a more comprehensive database and is easier to use than the Skywatcher but the Skywatcher HEQ5 Pro is quieter when slewing than the notoriously noisy Celestron CG5 (a consideration when using it in the urban environment - I don't want to disturb the neighbours at 4 am) and the Skywatcher is more accurate and incorporates periodic error correction & supports autoguiders while the Celestron does not.

As for price, the Celestron 9.25 Advanced GOTO with the CG5 mount comes in at FLO at £1695 including VAT but not P&P (less any SGL discount I can obtain) which seems reasonable. The Celestron 9.25 OTA is £1379 while the Skywatcher HEQ5 Pro comes in at £669 (both including VAT) making a total of £2048 or just £353 more than the Celestron Advanced GTO package. I also note that imaging god Ian King promotes the Skywatcher HEQ5 mount and Celestron 9.25 as an ideal imaging package over Celestron's Advanced GTO CG5 on his retail web site. I can't help but think that the 9.25 OTA & HEQ5 Pro for the extra £353 is the way to go. As I said, the EQ6 Pro is not an option (way over my budget and too heavy). This is also a set-up that I want to last me until I retire in 9 1/2 years time (think I've sold it to myself!). Kind regards.

[MartinB]

Sound thinking Brinders. Just one thing, the Eq6 pro is ok for most able bodied men. I have an EM200 which the EQ6 is cloned from. I'm not especially strong but am easily able to hook my arm under the mount with tripod attached and carry it 20 yards to it's resting place. It isn't an issue. If you have disabilities it might be a different matter

[Brinders]

Hi Martin. No disabilities, just a budget to keep to!

[FLO]

I'm hoping to do some astro photography eventually and I believe from FLO's site that the carbon fibre OTA will be more rigid and suited to astro photography but has a longer cool down time.

Following your enquiry Brinders I have discovered that Celestron no longer offer a carbon-fibre option. It seems the Aluminium tubes faster cool-down time is considered more important than the higher dimensional stability of carbon-fibre. To be fair, once the tube has cooled only a significant change in ambient temperature would effect focus.

HTH

[Brinders]

Thanks for the info, looks like it will be the aluminium tube then. That also answers the query about the dovetail. I'll be back in touch to discuss making an order soon (see my post under the First Light Optics heading).

Sincere thanks for the prompt reply and Merry Christmas.

[Brinders]

Sound thinking Brinders. Just one thing, the Eq6 pro is ok for most able bodied men. I have an EM200 which the EQ6 is cloned from. I'm not especially strong but am easily able to hook my arm under the mount with tripod attached and carry it 20 yards to it's resting place. It isn't an issue. If you have disabilities it might be a different matter

Now Martin, why did you have to go and post that comment? I've been thinking about it ever since. I had put the EQ6 Pro mount out of contention mainly because of cost but also portability (at least from garage to garden). Then while I was trawling the internet yesterday to see if I could get a better price for the HEQ5 Pro mount than the one from Steve at FLO (I have, at Pulsar-Optical, but I haven't done anything about it yet) I came across an offer at Rother Valley Optics for the Celestron C9.25 XLT on a Skywatcher EQ6 Pro mount for £2020 (plus £20 p&p). I was hoping to limit my budget to no more than £2000, but the offer with that EQ6 Pro mount is so damned close! Only problem is I'll have nothing left for dew prevention which, from last nights session, will be essential with an SCT.

Still I have another week or so to mull things over then I must decide and buy and hang the consequences!

[MartinB]

I got the impression that the EQ6pro is harder to lug around than it actually is. It was only at Kelling this Sept that I saw that that it is actually perfectly manageable.

Sound like a great deal. You don't need a fancy dew shield (says he who currently has one on order) - just a roll of stiff plastic sheet, some velcro and a pair of scissors should have you sorted to be going on with. A dew strap is good esp on dewy nights but if you keep an eye out for the first signs of dew and have a hair dryer handy you can get by.