C11-A XLT on a CG5 mount

[Lerxst]

Celestron pictures the C11-A XLT OTA on the CG5 mount on their web site, and according to some astronomy forums, the CG5 should handle almost 16kg (35lb), but is this with counterweights and all be pushing it to the extreme point where it's practically useless?

First of all and since this always comes up : No, I will not use the setup for astrophotography. It will be used only for visual observations.

And since I just got the CG5 I do not have the budget to purchase another mount either. I do realise I could go for the 9.25 instead of the C11, but I would like as much light gathering power as possible, so if the mount will take the C11 I will go for it.

[ollypenrice]

Probably at the limit and passed it for AP but since that doesn't matter...

Being on the limit will hamper high powers more than low, so factor that into the choice, I'd say. Also things like location. Are you out of the wind? These things all add up.

Olly

[Lerxst]

Yes, I forgot to add, I'm out of the wind. But you're saying high mag will suffer? Because being able to use high mag is one of the reasons I want such a big bucket...

[red dwalf]

one thing i`ve heard form folk who have had the c11 and c9.25 is that the 9.25 is not far off the c11 in visual comparrisons, plus the 9.25 is lighter of course.

[Coco]

Olly make a good point, 2800mm and a weak mount = bouncing stars, also try getting critical focus when your target is bouncing about on the eye piece, you should factor in an electronic focuser

Guy

[Coco]

one thing i`ve heard form folk who have had the c11 and c9.25 is that the 9.25 is not far off the c11 in visual comparrisons, plus the 9.25 is lighter of course.

Ive heard the same, @ 2350mm lighter tube, sharper? and all together more manageable, ive only ever owned a CPC800 which was still an amazing bit of kit, the C9.25 would be awesome..

If your bringing the OTA from inside a warm building its going to take a long time to let the 11" of glass cool down

Guy

[Lerxst]

Okay, and please bear with me since I was unable to find the answers to these questions with Google: How much difference in light gathering will that mean? What will this mean visually when observing DSO's and planets, i.e. details?

Also the star diagonal on both the C9.25 and the C11 are 1.25". I thought 2" was standard on telescopes above 8"

[dweller25]

I had a C9.25 on a CG-5 which I used around x250 on the planets. The mount just managed to hold the scope to within a couple of seconds of vibration when focussing. That may not sound a lot but it's irritating when trying to achieve critical focus on the planets.

In my opinion the C11 will be very undermounted on a CG-5 and a HEQ5 - you will need an EQ6.

BTW you can put an 8" F/6 Newt on your CG-5 which will outperform a C9.25 (23% obstruction v 36% obstruction) and is much cheaper and cools quicker.

[Lerxst]

BTW you can put an 8" F/6 Newt on your CG-5 which will outperform a C9.25 (23% obstruction v 36% obstruction) and is much cheaper and cools quicker.

Hmm, I thought a Schmidt-Cassegrain was a step up from reflectors? If not, wouldn't a 10" (providing it's not too heavy) reflector be the ultimate choice?

[Luke]

Re: C9.25 vs C11, the C11 has about 40% more light gathering power.

Some people say you get better contrast on the C9.25, but you might get a touch more colour through the C11. From what I read the C11's bigger light gathering helps on faint deep sky, but for planets, some say you get better contrast through the 9.25.

Re: can the CG5 take the weight of the C11, mixed views here, some say it is okay for visual but with some saying it might be pushing it for high power mag, some say others manage to do imaging as well just fine, it seems it's near the limit.

Review from Damien Peach here on the C9.25 if you haven't seen it:

Courses in Astrophotography

Re: reflectors vs SCT, I think one factor is that the SCT is F10 so to match the focal length you'd have to have a crazily long reflector or refractor, and if you want to speed up the scope there is the excellent focal reducer (F6.3, I think). For me the SCT is just super versatile, fantastic on planets, good on deep sky, compact for the focal length, but you pay for it in the price.

C9.25 vs C11, nice problem to have!

[Lerxst]

C9.25 vs C11, nice problem to have!

Thank you for the info. Between you and me, I am in the bizarre position that my employer will (hopefully, not 100% decided) pay for the telescope, hence the «problem».

[NickH]

The CG5 is not fit for purpose with a C11 end of story....plus the thing sounds like the back end of a 50cc scooter when slewing. Most of the people who get the C11/CG5 package flog the CG5 as new on astro buy and sell..

C11's do suffer with mirror flop on the old model (not on the Edge version).. for my money...today, it would be an EDGE HD version

[moocher]

I've had both scopes and the c9.25 was a joy to use. The c11 on the other hand!!! I'd go for the c9.25 if it was me.....

Alan

[dweller25]

Hmm, I thought a Schmidt-Cassegrain was a step up from reflectors? If not, wouldn't a 10" (providing it's not too heavy) reflector be the ultimate choice?

Yes - a 1/8th wave 10" Newt with a 20% ish obstruction will be a formidable telescope for the planets and deepsky and more than a match for a C11.

[NickH]

It's down to focal length...try getting that 10" newtonian to F50-67...which is where Pete et al are imaging Jupiter etc at

[brantuk]

The Schmitt Cass is a reflector too. Plus - if your boss is buying the scope then I want a job there lol

[Rossco72]

First off, I've never had a CG5 mount so I can't comment on that. I do have a C11 though and have used it on my EQ6 and CGE both for imaging and visually. In both these mounts there was no problem at all except for the need of an additional counterweight to achieve a good balance.

As for the scope, well the views are great, there are fantastic images on the web taken through C11 and C14 scopes. A nice feathertouch microfocuser really helped with any focusing issues and all in all it's a very nice bit of kit. Would an Edge HD version be better, i'm sure it would but then that's what you are paying that premium price for.

[NickH]

Snap, love the C11, superb scope, bit heavy, but works fine on the EQ6...my issue with it has always been the lack of mirror lock on the original, which is something they addressed on the edge HD

[michael.h.f.wilkinson]

I would think a 10" Newt would be LESS stable than the 11" SCT, simply due to its length. If you touch the scope near the focuser, the torque is higher. You also tend to get lower-frequency oscillation, which generally have longer damping times. Portability also favours the SCTs. The C9.25 (EDGE) would certainly be a neat scope, and well within the limits of the mount. At 12.5 kg, the C11 should be OK, but with counterweights, diagonal, EPs etc, it may start pushing that limit.

[ollypenrice]

The CG5 is not fit for purpose with a C11 end of story....plus the thing sounds like the back end of a 50cc scooter when slewing. Most of the people who get the C11/CG5 package flog the CG5 as new on astro buy and sell..

C11's do suffer with mirror flop on the old model (not on the Edge version).. for my money...today, it would be an EDGE HD version

You can rely on Nick! Spoken with characteristic lack of nonesense!!

Olly

[NickH]

Cheers Olly...I do like to say it like it is...

Take no prisoners...

What also always fried my head was that the CG5 with C11 was cheaper than the C11 OTA only...go figure! Thankfully I think they've resolved that now..

[ollypenrice]

What also always fried my head was that the CG5 with C11 was cheaper than the C11 OTA only...go figure! Thankfully I think they've resolved that now..

I know, it's like train tickets. One time it was cheaper to Edinburgh than Newcastle so the Geordies all bought those and got off early, till they were told they couldn't get off early. (Heh heh, keep a Geordie from his Broons??) Maybe Celestron say you are not allowed to remove the C11 from the mount if you buy them together...

Olly

[Lerxst]

Thank you all for your usefull input.

I will go for the C9.25 instead.

And bizarrely enough, my employer will pay for it. I won't bore anyone with the details, but they went very quiet when I told them exactly what I wanted. I bet they expected me to say something like a new computer or a LED TV.

Still, nice employer, don't you think?

A final question; two, actually:

1. With visual observing, what can I expect of DSO's? With my F/8 reflector, M31 is so fuzzy it's possible to see that there's something there, but not much more than a faint, grey blob.

If DSO's are my thing, which scope should I go for?

2. Will a focal reducer help on DSO's as the C9.25 is a F/10?

[NickH]

DSO's are your thing (and M31 in particular) then an F10 SCT is probably not the best choice, and not one on an average mount.. an F6.3 will help, but a wide and fast 12" to 14" goto dob would be better, F5, and more light grasp with larger aperture

if you're in to imaging DSO's then a good F5 ish refractor on a HEQ5 would serve you way better

[Merlin66]

I have the C9.25 on a NEQ6pro mount, no issues!!!

If you are considering imaging DSO etc then yes the x0.63 or a x0.5 (Optec) reducer is the way to go.

BTW the C11 allows for the Fastar f2 secondary adaptor the C9.25 does not.