Owners of Celestron C8 SGT on a German E Q mount your help needed.

[Dennis G]

Owing to a sudden change in health, I need to purchase a scope I can handle and transport in a small vehicle at a reasonable cost. My main interest is imaging. The Celestron C8 SGT on a German Equatorial mount interests me, but I'd like to find some one who has this scope and who is willing to give me their opinion of its ability to track accurately and its stability. If some one out there would kindly reply to the above questions and these below, it would be greatly appreciated:
How difficult is it to assemble and pull down?
What power supply is required? Voltage etc.
Can the finder scope be fitted with a 90 degree prism instead of the straight view?

[asterisk]

Hi Dennis

I have a Celestron C8 and a CG5 AS-GT mount (although I now have the C8 on an EQ6 mount instead - see later).
Not difficult at all - counterweights, counterweight bar, mount, tripod, OTA

12v at a minimum of 2 amps - jump starter packs are suitable, although for sustained long-term use I would recommend a deep-cycle battery

Yes - comes with a 6 x 30 - I would recommend replacing that with a wider field of view finderscope and/or laser pointer/red dot finder. The initial accuracy of the controller can be well off the mark until at least 2 alignment stars and 2 calibration stars are included.

Now we have moved into a completely different area.
For visual use, the CG5 mount is quite capable. Imaging - DSLR or CCD? Guidescope with autoguiding? Adding a wide field guidescope to the C8 with all the associated cameras and dew stuff starts to overload the CG5 and it is not as good as a mount such as the EQ6 for imaging.

Please ask if you have any further questions.

Cheers

[sheeny]

G'Day Dennis,

I second Geoff's comments.

I replaced my finderscope with a 9x50 right angle finder from Bintel when I set mine up in the observatory. I used to use my tripod at full height and the standard finder was OK... now on a lower pier, the right angle finder is a must (as it would be if you want to use the tripod in a low position).

This rig's suitability for imaging depends on the type of imaging you want to do. It's fine for lunar and planetary imaging with a web cam, and I've found it to be OK for piggybacking a DSLR for wide field shots (but you may need an extra counterweight).

I would think you would be disappointed with performance for long focal length long exposure stuff (DSOs) unless you have a camera with a built in guiding chip, or can master an off axis guider. I think the mount will struggle with the addition of a guide scope.

Al.

[Dennis G]

Thanks Al and Geoff. Now I've made contact with you both I'll add a few details why my questions. I have a 10 inch dob My Light Bucket, which I built with eq platform, its been described in equipment section IIS. I've been imaging the moon and planets using DMK imager and had hoped to have similar success with the proposed Celestron on deep sky objects ?
I survived a heart attack last year and now require an easier assembled and transported scope with quality in mind. As much as I'd like to own an Altz mounting scope such as the Meade 8 inch, living in the South West Aust, freight kills eastern states purchases. Andrews advertises Celestron C8 SGT, the mount type is not mentioned . I'll have to check . It will need to be the EQ 6 to satisfy me.
Do reply with any advice. you may feel to my advantage. I'm 82, but not too old to accept advice.

[sheeny]

Sounds to me like a C8 XLT OTA with an EQ6 mount is more the way to go than the C8 SGT (which is the C8 on a CG5 mount).

Have you thought about the C9.25? It's a little bigger than the C8, but by all reports the optics seem superb. If the extra cost and/or weight of the C9.25 isn't a problem, that'd be my recommendation.:thumbsup: Make sure you get XLT coatings. If you have an option for the carbon fibre tube, that's good for stability of focus over varying temperature.

One other thought to keep in mind - focussing. On the CG5 I found the vibration while focussing very annoying and made focussing difficult. I'm reasonably sure the source of the flexibility is the aluminium dovetail bar on the OTA but there could've been a component from the mount. All that ceased to be a problem when I fitted a Celestron Motofocus - JMI also make the same sort of thing. Other people have used all sorts of other focus solutions too.;)

Al.

[asterisk]

Dennis, the Celestron C8 SGT advertised is on a CG5 mount. As I said, good for visual, touch and go for imaging - depends on what else you add to the mount. As Al states, with the CG5, "the vibration while focussing" is bloody annoying - I have a Featherlite microfocusser fitted to my C8 and making the last adjustments is a pain in the neck - focus, wait for vibrations to stop, refocus, wait, etc ...

I still have the same aluminium dovetail on the C8, but the vibrations have gone with the EQ6 mount. You write "It will need to be the EQ 6 to satisfy me". The EQ6 is not a light mount - will you be able to handle it? I have seen discussions where the EQ6 is classed as a mount for leaving on a pier - I carry mine around, but I am yet to turn 60.

Al's suggestion re the "carbon fibre tube" may be good for reducing weight, but the mirror will still add to the overall weight with a 9.25".

If you are after a Celestron Motofocus, I have one I am not using.

If in doubt about whose advice to follow, Al has been observing far longer than I - I have personal knowledge of my travails with the setup you first mentioned, but Al has much more experience overall.

Cheers

[Dennis G]

I appreciate the advice that you both have provided. Since writing I have had 4 days in the middle wheat belt and until we had a weather change, what I'd have given to have had my scope with me. You could reach up and touch the stars!
Back to a few thoughts I've given to this scope purchase, that require answers. With my self made 10 inch dob, I have concentrated on recording the moon and planets, first with a Toucam colour imager and later with a mono DMK24, direct to a laptop and processed the results in Registax and Photoshop. Using this equipment (I'm not conversant with tracking a star etc with an added scope) The EQ plaform and its hand held control is self made and if I'm able to get the South celestrial Pole spot on I can hold the object reasonably stationary for 700 frames with the controller by speeding up or slowing down a little at a time.
Question: Using the Celestron 8 inch on the EQ5 (They don't supply a EQ6) and the DMK imager recording into the laptop, can I expect to capture the Orion Nebula for an example? Deep Sky capture?
The focus disapointment you both mention. I have a JIM style focuser on my Dob and to prevent shake I built a remote control, (Shown on IIS) which works well, but whether it will work on the Celestron I have no idea. If it is able to be attached, it focuses both course and fine without any vibration.
Question:You both write of a carbin fibre tube? Are these available as a standard unit?
Question: The Go To facility, you may term this, when the telescope EQ mount is being powered to compensate the earths rotation, while recording for half to a minute, does it require constant manual control or putting it another way , is it stable?
The cost of the Meade has made it difficult and it looks as if the Celestron on the German EQ 5 will have to satisfy me. I'd appreciate your reply.

[Dennis G]

A question I missed to ask. What is the difference between a EQ 5 and a CG5 mount or put another way what is a CG5 mount.

[Chippy]

Hi Dennis,

The CG5 mount is fairly similar to a Synta/Skywatcher HEQ5Pro. Same weight rating, and both goto mounts. Celestron do actually offer a mount which is comparable with the EQ6Pro now as well. It's called the CGEM mount, and Andrews have them listed at the bottom of the CAT section. Quite a bit more expensive than the SGT (CG5) version of course.

It is worth mentioning that there are at least 3 versions of CG5 mount floating around, and the newest version of these is more stable than older versions (and has 2" tripod legs). I would actually be surprised if you couldn't do some reasonable imaging with a C8 on one of these newer CG5's - but I have no experience.

The tracking on these mounts is very good generally, if your alignment setup is good. I would expect subs of a minute or 2 would be quite achievable without guiding - but again no experience.

I don't know if the C8 is available in CF. The 9.25 certainly is, but you will pay more.

[asterisk]

The easiest first. CG5 is a GEM from Celestron which is not a sturdy as the EQ6 GEM made by Synta (yes, I know Synta now also makes Celestron gear). The EQ6 is able to carry more weight with less problems than the CG5.


I have not used the imager you mention. My DSLR images of M42 on the CG5 were nowhere near as stable as on the EQ6.


Yes. Andrews have a GSO RC-8" SDX...A$2499.00 - a bit dearer than your standard 8" SCT, but lighter and theoretically better optics.


The GOTO part is for finding the target, and if the mount is set up properly, is reasonably accurate on both mounts. To achieve tracking of the target over longer periods, then drift-alignment is vital to ensure the RA axis is aligned correctly. Manual control is generally not necessary. Many people (me included) use autoguiding to ensure the target stays in place.

Motorised focusser - The one you built for your Dob probably will not work on the SCT - smaller and different focusser.

Cheers

[sheeny]

Isn't that always the way!;)


Yes... but the longest single exposure you can take will be limited by the accuracy of your polar alignment, and the speed the mount tracks at unguided unless you add a guide scope etc. M42 is pretty bright as DSOs go so you can take unguided images of up to several seconds at prime focus if your alignment is good, but for longer shots you will really need to guide.

If you really want to do deep sky stuff, I would recommend the EQ6 to give you the stability you need to run a guide scope as well. The CG-5 will disappoint under that sort of load.

I know the carbon fibre tube is available in the C9.25 and larger scopes. I suggest you ask the supplier if they can get the C8 in carbon fibre and then weigh up the cost difference.

It is pretty stable. The problem with goto drives is that though they are pretty constant, they may vary in speed slightly with temperature, or your alignment will probably not be perfect, or atmospheric refraction will change the rate of apparent motion of the object as it rises or falls in the sky, so guiding is used to correct for these differences between the observed heavens and the drive's speed.



I'm not sure if the CG5 is equivalent to the EQ4 or EQ5. Someone correct me here if I'm wrong, but I think I've read somewhere that the CG5 is equivalent to an EQ4:shrug:, but I'm relying on memory here so I'm on shaky ground:P.

It sounds like, from your description of your interests in DSOs that the EQ6 would be my first recommendation for a mount, and a HEQ5 as next best, then maybe an EQ5, followed by the CG5.

Al.

[asterisk]

Damn - I knew I left something out! Well summarised Al.:):)

[Chippy]

As I mentioned, the new CG5 with 2" legs is improved. Better than EQ5 I believe.

[sheeny]

Thanks. I stand Corrected!

Al.

[Chippy]

Well I'm only going on what I read, not direct experience. So take that FWIW.

[asterisk]

Sorry Nick - I have the new CG5 with the 2" legs. I also have a new EQ6 and the legs are the same as the CG5 - the only difference is the plate for the mount and the azimuth adjustment peg.

The tripod legs, being the same in both, do not contribute to the stability and load carrying capacity of the mount. The EQ6 is the more stable mount of the two.

Cheers

[Chippy]

Nothing to be sorry about - but of course the EQ6 is more stable. Its rated for 20+ kg. The new CG5 is rated at about 13.5kg (similar to HEQ5Pro - which is what I said). EQ5 is about 10kg. The old CG5 was rated about the same as EQ5 I believe. The 2" legs do make a difference if you read peoples comments (extra weight = extra stability for starters). I don't think anyone ever suggested the CG5 was like an EQ6 though...?? Certainly not me!

[Dennis G]

Thanks guys for your replies, there's more to it than what one reads in the ads. But I cannot buy a C8, there are none in stock, so now its become necessary to change direction. I have to give weight a serious consideration. The Celstron tube is now only made in aluminium and weighs 10 kiloes One supplier quotes 17 kilos for the Meade LX90 8 inch and another qotes it at 12.5 kiloes either is a load to lift to chest height to assemble and the cost shoots up an extra 1200 dollars plus another 200 odd dollrs for a wedge, which adds more weight, the reason I chose the Celstron. Saxon advertises an 8 inch F12.5 Maksutov-Cassegrain optic tube for $1398 , the go to mount is extra. Is this type of scope any better or worse than a Schmidt -Cassegrain? The picture of the go to drive mount looks light on.
Who sells QE 6 mounts?
German Eq drive photographs always show the scope in what I'd term a vertical position and the balance shaft and weight facing downward. Assuming one sets the Go To drive to find an object close to the horizon. Would the scope and balace arm move close to the horizontal?

Do these Celestron Scopes come with rechargable internal batteries or can exturnal power be plugged in?

[asterisk]

Hi Dennis

Have you tried Andrews Communications? http://www.andrewscom.com.au/index.htm. They may be in outer Sydney, but they ship all over Australia. The only concern is if you have a problem, they are not local. They have OTAs, EQ6 mounts.

Yes - not a problem if everything is balanced



If you are looking at the CG5 mount, no internal power - must be external 12v at 2amps at least. Some of the other Celestron mounts do have internal batteries, but rechargeable batteries do not have enough voltage.

Too many answers depending on whom you ask. An 8" Mak would certainly weigh more than an equivalent SCT.

[Dennis G]

Many thanks to you all for your assistance. I've received the speci of the Meade LXD 75 8 inch on a good looking EQ German mount from Astro Optical supplies. If you have time to look it up and comment I'd appreciate it. The brief speci UHTC (?)
Aperture 203 mm. FL 2000 mm. F 10. Accessories Highlight Autostar. 8x5 finder scope. Images (?) and I assume from the speci it is a Go To.