Celestron 925?

[fatwoul]

I currently have an old Vixen refractor on an equally ancient Polaris mount (and a tripod that is actually rusty!).

I am looking for a new scope for the summer. I want something that will be a good all-rounder, but primarily for DSOs. My main interest is imaging, but I would still like to be able to do visual observing too.

My budget is up to £2,500.

I am currently considering a Celestron 925, either on the CG-5GT or CGEM mounts. My research so far has told me that this scope is a respectable jack-of-all-trades, but you guys would know better than I.

I'd also like to be able to mount my Vixen onto the new mount, with the new telescope. It's possible that, as my interest continues, I would want to move to a larger scope. These are my two main reasons for considering the CGEM, which I understand is a little more substantial, and more capable of supporting additional weight in the future.

So, based on everything I've said, do my choices seem sensible? Are there any considerations I should include? Should I scrap the Celestron idea altogether and look elsewhere?

I also have a retailer in mind, who I have read good things about, but I won't mention names because I'm not sure if it's polite to do so here.

Any advice would be greatly appreciated.

Thanks everyone.

[russ]

The scope is certainly a good choice. I've used one quite a bit and it's superb. The one i used was initially on a CG5 and i certainly would not recommend that. Wobbly is the best way to describe it. But once the scope was transferred to a Losmandy G11 it was a dream to use. As i imagine it would be on the CGEM. That C9.25 now sits dorment (has done for a few years) because the owner prefers his Tak refractors. What a waste!

[GuillermoBarrancos]

The scope is certainly a good choice. I've used one quite a bit and it's superb. The one i used was initially on a CG5 and i certainly would not recommend that. Wobbly is the best way to describe it. But once the scope was transferred to a Losmandy G11 it was a dream to use. As i imagine it would be on the CGEM. That C9.25 now sits dorment (has done for a few years) because the owner prefers his Tak refractors. What a waste!

The new Advanced CG-5 GT mount is a heavy beast tho and should be easily able to handle the C9.25.

But the question is, if he wants to put up the Vixen refractor alongside the C9.25 at the same time. And how big and heavy this refractor is.

If it's a big heavy refractor, then a heavier mount will be needed and a CGEM would be a better choice.

Seeing he has a 2500 budget. I guess going for the CGEM would be a no brainer anyway.

[russ]

The 2" steel leg CG5 should cope a lot better but i think with a dual scope setup in mind, the CGEM would be a better bet.

[Rossco72]

For the cost of a new CGEM you might just be able to pick up a used CGE if you look around hard enough. In fact for your budget you should be able to get a used CGE and a good condition used C9.25", possibly from the same seller!!

Just a thought, if you are looking for new though then my thoughts would be towards the CGEM.

[fatwoul]

Thanks, guys.

You're right, I omitted to mention what size the vixen is. It's a 102, I think, although all the stickers are long gone. Optically the scope seems fairly decent, and to be fair the mount is capable of doing a reasonable job for observing. Unfortunately, I think its astrophotography days are over, and it is definitely not up to holding a second tube, particularly a medium sized SCT.

[ollypenrice]

Lots of talk about wieght, here, which is fair enough, but what has not been discussed is the very high degree of tracking accuracy required to image with a scope of that focal length. In my opinion reliable tracking at these focal lengths is certainly not budget mount territory. I Would not risk splashing on out on the scope unless I were going to mount it on a G11, Tak EM200, AP Mach One or better. You might get the the tracking accuracy, but is 'might' good enough? You risk finding that after buying the SCT you needed to spend a hell of a lot more on a really workable mount.

We have 2 EQ6 mounts and I have never wanted to take them beyond a metre. If you want them to guide in a really accurate way for long Ha subs (for instance) then the comfort zone of budget mounts stops there. At shorter focal lengths they are very reliable. This would inform my choice of OTA.

Other SCT issues; you need a reducer. If you go for the Edge version it seems a reducer is available now or will be soon, but check first. This is on my list of scopes, so I'm not against them.

You need a proper focuser, a 2 speed Crayford or similar. I will never go near moving mirrors for imaging again!

Long focal length means very limited choice of targets. I'd be getting one just for the galaxy season and little else. The SCT would be good visually (I have used one and been well impressed) but give me a 5 inch refractor any day as a scope for nebulae and clusters as well as just the little galaxies and planetaries which will be your quarry in the SCT.

Olly

[MartinB]

Similar thoughts to Olly but just to add that the 9.25 is a superb instrument for solar system imaging. It also has the potential to be a great DSO imager but there are quite a few issues to address as Olly has pointed out -

challenging focal length - not just a problem with tracking but also seeing conditions

focus changes with temperature

field curvature

image shift with the standard focuser

mirror flop makes an external guide scope unreliable

All these problems can be overcome with a bit, actually a lot, of patience and perseverence.

On the other hand. You could get yourself a DMK planetary camera and double it up as a fun DSO camera using a Meade 3.3 reducer doing unguided imaging. A great way to start!

[kris h]

Hey fatwoul

im saving up for a cgem mount with a 8 inch scope it will cost me under £ 2000 but ive seen a celestron edge hd 8 inch for £2300 with a cgem mount from orion telescope binoculars.

kris h

[fatwoul]

Thanks Olly and Martin. Good advice in terms of quality, and I am aware of the fantastic equipment produced by Takahashi, Losmandy, etc, but I'm sure you would agree that those mounts lie far outside my £2500 budget, long before I've even put a telescope on top of them!

Right now, I'm just looking for a respectable all-rounder to get me back into astronomy and astrophotography. I still have the Vixen, which is an 80M, by the way, now I am home and have actually been able to measure it (apparently I suffer from a common male problem of things not being as big as I imagine them to be!)

EDIT: In fact, the Vixen wouldn't be the heaviest additional item I'd want to mount with my new telescope. Weighing 5.5lbs, it would come second to my 200-400mm, which is a little over 7lbs. Typically, I use my D3 on that lens for much wider field stuff, and a D300 on the back of the Vixen for narrower stuff

[GuillermoBarrancos]

Just check Paulobao's Pics on this forum.

He makes some really stunning DSO pictures with a C9.25 + focal reducer. And so are there many others on the net.

The C9.25 was a tad above my budget. So I went for the C8 in the end.

I just bought the Baader Hyperion 8mm eyepiece.

A QHY6 CCD and Celestron 0.63 focal reducer are next on my saving list.

After that I have to make the hard decision to go either for an Off-Axis guider or save up and go for a small scope for guiding.

[beetlejuice]

The C9.25 is a great scope but suffers as all SCT's do from relatively poor contrast and field curvature, though the latter is less than on other SCT's as Celestron designed it as a photographic scope from the beginning. I mount mine on an EQ6 Pro via a Losmandy dovetail and it's rock solid. The CG5 is adequate for visual but useless for photography with a C9.25 on it, but I do use it occasionally as it's a lot lighter to transport. I bought my EQ6 new and the C9.25 secondhand but mint. Total cost, by the time I'd added a few goodies, was around £2K, well below your budget, and worth every penny.

[fatwoul]

OK, so let's say I forget buying a kit telescope like the CGE925 and decide to build my rig from the ground up.

Which would you say would be more suitable for astrophotog between the CGEM and the EQ6 Pro SynScan?