Celestron CG5 mount

[Johno]

Can anyone give me an opinion on the Celestron CG5-GT mount? I'm considering the C8 or C9.25 S-GT and was wondering how well it tracks and how accurate the Goto is.
As an alternative I'm thinking of putting the Celestron OTA on an EQ6 with the SynScan Goto. Any opinion on which would be the better option. The EQ6 is the more expensive option and I think I would prefer the Celestron Goto system so it leaves me wondering how good the Celestron CG5-GT is.

If you have had any experience with either system I would be grateful for your comments.
John.

[Robert_T]

Hi John, I don't have the CG5 just a plain old eQ5 with no go-to - it's essentially the same mount as the CG5 in every other respect, but obviously I can't comment on the goto function/accuracy. I find this tracks fine for planetary imaging, but doubt it would be up to long exposure stuff except perhaps at short focal lengths. I have the EQ5 setup on a pier which makes it very stable and capable of carrying the C9.25 without any trouble. The new CG5's have the 2inch steel tripod legs which are excellent and probably the next best thing to a pier.

I bought another mount for the C9.25 more recently. I considered the EQ6 with skyscan and gave it a good going over, but in the end chose the Meade LXD75 which is effectively an equivalent of the CG5 GoTo. This is a very personal thing. For me portability was paramount, I didn't want it to be a struggle to setup and take down and the EQ6 is BIG! The LXD75 handles the C9.25 nicely all the same. Again it's not a long exposure imaging setup.

Hope this helps a bit.

cheers,

[g__day]

For a list of GE goto mounts with their RRP and their tracking abilities read here:

http://www.iceinspace.com.au/forum/showthread.php?t=8135

THE CG-5 is a basic, low weight mount that can handle 8" scopes or slightly larger at a strech, but long duration astro-photography is beyond it.

[seeker372011]

I must disagree. The statement is true only if the mount is not guided.
Manually guided I have gone 5 minutes with an 8 inch and autoguided, I have gone as long as 20 minutes with an ED 80 and 5 to 6 minutes with an 8 inch Newtonian.(havent done much imaging with the 8 inch so cant say this is the limit) You must be well polar aligned though

[Miaplacidus]

Yeah, but let's face it Seek, you perform miracles with an ETX. Hardly typical.

[Johno]

Thanks everyone for your comments. The goto mounts list is very good. Looks like I have a lot of factors and compromises to reconcile.

[g__day]

Plus I'd say 4 - 6 hours is long duration, anything over 20 minutes is probably getting quiet complex. Auto-guiding will give you alot more precision of course, but are you saying add auto-guiding and a EQ-6 or CG5 are as good as say a CGE or G-11 also with auto-guiding? The extra $3,500 between a basic mount and a higher quality one should be discernible, isn't it?

[OneOfOne]

I have a C8 NGT and generally agree with the points made already about tracking. I haven't taken any shots with mine yet, but the pointing accuracy seems pretty good, even if I don't take a huge amount of care.

At first I didn't have an eyepiece with an alignment reticule and just "centered" the three alignment stars by eye. Generally most of the goto's were good enough to get the target pretty well centered.

When I bought the reticule (I got the Celestron one) it improved the goto a bit more. Most objects will be within the central quarter of the view in a 50-100x field....not bad. I just "plonk" tripod roughly pointing south.

If you REALLY want to take long exposures in the shorter term, you may want to spend a little extra and get something "better" now. As for portability, the EQ5 fits in the boot of the car (Sonata) only after I remove the head assembly, you would need a wagon of some sort to leave that in one piece.

[seeker372011]

[QUOTE=g__day]but are you saying add auto-guiding and a EQ-6 or CG5 are as good as say a CGE or G-11 also with auto-guiding? QUOTE]

Of course not..the CG5 is not in the same league..however if you can get 70 to 80 % of the performance and spend many many thousands of dollars less...that is the price-performance trade off that one can make. If money were no object then of course that puts a different perspective on the decision.

For many locations about 5 to 10 minutes is the sky fog limit so that is, in practical terms, long enough for sub frames

[g__day]

Well Sydney in Summer is cloud central, but in Winter you get quite a few nights with few clouds (just windy, light polluted and cold)! So longer duration astro-photograpthy is conceivable.

I'm interest in your thoughts of how a CG-5, LX75 and EQ6 (circa $1,200 -> $2,200 mounts) compare to a G-11 or CGE at 3 times their price with GoTo. Do you actually get 70% - 80% of their performance with auto-guiding? What is the real difference in capability and quality achieved and is this only a 20% - 30% fall off, or is it a cliff once you get into longer duration or some other more challenging task?

Anyone know or care to comment?

[Johno]

Interesting comments all around. It seems apparent that everyone agrees that the CG5 or other similarly priced mounts (including the EQ6?) are not suitable for long duration exposures but OK for visual. If I wanted solely visual use then I would probably have no hesitation in going for a fork mount but I'm thinking of doing a little bit of basic photographic stuff too (you know, some shots like that David Malin bloke takes ;-)). So what is the boundary between short and long exposures for one of these (non-guided) mounts? Obviously depends on several factors including alignment and magnification but would it be in the order of a couple of minutes or more than that? Would I have to exclude all DSOs?

[seeker372011]

I am not at all sure that everyone agrees that the CG5 or similar is not suitable for astrophotography.

However- unguided -you would be lucky with very good polar alignment to get more than 30 to 45 seconds without star trails.

Here are some random examples of images taken by myself with this mount and an ED80. There are a few more examples scattered here and there in this forum. Not the greatest images, but I believe they do demonstrate the possibility and potential.

http://www.flickr.com/photos/91784720@N00/

Check Jim Solomon's work with the same mount ..he is far more skilled than I ever will be-he uses an 8 inch Newtonian or an ED80

http://www.saratogaskies.com/index.html

Frankly its not only in the mount...look at the stupendous work Scott (tornado33 in this forum) does -he doesn't use a Losmandy or even autoguiding..and the work Tony Hitchcock (Itchy) does with an LX75 (many people write this mount off as useless, and yet he consistently produces the highest quality and award winning images ). Tony uses a very large number of relatively very short images to overcome mount limitations.

As I said before, by all means get the best mount you can afford..but all is not lost if you can't afford-or dont want to invest in- a Losmandy or a Paramount or whatever just yet.

my 10c :)

[seeker372011]

Its not cloud or the absense of cloud that is the problem it is ambient sky glow which fogs out the image. (I have gone as long as 20 minutes with this mount on exceptionally dark nights). Also by limiting the exposure for each sub- frame you reduce the risk of a plane or a stray headlight or something ruining your entire nights effort. You can always toss one 5 minute image-losing a 50 minute image would be enough to make a grown man :(

I was actually being conservative in stating that the cheaper mounts deliver 70 to 80 % of the performance--some amateurs go as far as 90 %!

Perfection is expensive-its getting that last extra bit of excellence that adds all the enormous cost. No one can deny the superiority of these top end mounts..as a sort of analogy would a Hyundai take you from point a to point b about 70 % as well as a Lexus?

[seeker372011]

For a warts and all view of the CG5 mount check out the Yahoo group

http://groups.yahoo.com/group/Celestron_AS/

also check out the FAQ in particular

[Striker]

I personaly wouldn't put a C9.25 on a EQ5 or CG-5 mount for astrophotography...once you have the C9.25 then you have to think of a guide scope plus plenty more accessories hanging off it.

I'm sure you could make it work but it definetly wouldn't be optimal....you could probably get away with it imaging planets but DSO's would be a much tuffer ask.

I had my ED80 and WO 80mm Zenithstar guide scope on the EQ5 with stainless steel legs and I wasn't happy with it's performance.

A lot is going to be determined on what Focal length your imaging at....the mounts not going to make a huge difference imaging at 600mm Focal length but if you plan on imaging at say 2300mm then I'm afraid you will be dissapointed with a CG-5 or EQ5.

My motto is your better off to big then to small.

My personal opinion

[g__day]

I ponder that more expensive mounts exist for a reason, and the owner of a less capable mount may be quick to dismiss them without sufficient understanding of their capabilities and purpose.

Ambient sky glow primarily results from sodium based street lights, and their are filters that target exactly this wavelength for under $200. And this wavelength is uncommon in stars so it shouldn't dim them!

I'd be interested in understanding when you say a cheap mount can achieve 90% of the capabilities of a far more advanced mount what you are using for your comparision and what factual data you have that clearly shows this result with some accuracy and precision. It sounds seat of the pants with no clearly agreed scale or capability set you are basing this outcome off.

Can you be more detailed in your assessment please?