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CG-5 and C11 the good the bad and the ugly

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#1 dr.who

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Posted 28 September 2012 - 11:12 PM

Title says it all.

I have both and decided to run it them through their paces tonight. *BLEEP* night to do it from a viewing perspective what with the moon almost full and up and a bunch of water in the sky and os on and so forth but you take what you can get <shrug> and i haven't been under sky since last week so I was Jonesing :vomit:.

Bottom line... It's doable. *BUT* not recommended. Reason being is twofold. First is vibration. Second is that at certain angles and positions the motors really really strain. To the point where they start to run away a bit.

On the subject of the first reason, I am fitted with an Orion Skyview Pro 16" pier extension for the CG5, and had vibration pads under it so there was quite a bit of weight and vibration mitigation but there still was noticeable vibration each time I touched the focuser that would take about a second to settle. I was on a solid surface driveway though.

On the subject of the second reason I did have it balanced pretty well and a bit East heavy but at certain positions near zenith the motors would start to strain and at a couple of points even gave a runaway sound. So to me that would mean that I was a bit off on the balance but it was still an issue.

So I would say C 9.25 max on it with a C 8 being a better choice. Anything bigger and it's time to go to the CGEM or bigger. Sure you can do it but then again you can also slap yourself in the face really really hard... :D

Hope this helps someone trying to make this kind of decision. Still a great mount. Still a great product. Still highly recommend it. But just not with a C11.

#2 rmollise

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Posted 29 September 2012 - 08:10 AM

Dang those Bleepy nights. :lol:

I've used this combo for numerous years--a buddy has it and loves it.

We've never had any trouble with motors "straining" or starting to run away "a bit," whatever that means. The CG5 C11 combo has always been bang on with its go-tos with good tracking.

Some suggestions: First, put vibration supression pads under the tripod leg tips. Running this combo without them on a paved surface is asking for trouble. Also, I can't see how using a pier extension would help anything.

Also keep the rig balanced. That's important, not so much because the motors might be damaged or something, but to keep the go-to accurate.

One important thing my mate did to his CG5 was to install a large, strong tripod spreader/tray. These can be bought or made fairly easily and really do help.

;)

#3 jgraham

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Posted 29 September 2012 - 08:22 AM

I've mounted some very heavy loads on my LXD75 over the years and this mount has similar characteristics to the CG-5. As the weight increases ballance becomes very important as does the moment of inertia.

#4 dr.who

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Posted 29 September 2012 - 11:01 AM

Cheers guys.

I did have the vibration pads under there per your recommendation Rod. Still had a good bit of jiggle. I went with the pier because it kept the legs fully retracted (and because I use the ES 127 with it) and because it puts a bit more weight on the tripod end. The more I think about it the more I think it may have been a less than perfect balance situation.

The other thing I realized is that the focuser on the OTA is a bit stiff. So I am going to run it up and down a bit to see if I can redistribute the grease. Either that or replace it with a Feathertouch.

I will try again and try for much better balance and report back.

#5 dr.who

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Posted 29 September 2012 - 04:47 PM

Upon reflection "run away motor" was the wrong choice of words. What I was trying to describe was a straining motor. As it approached zenith it would race up to a high pitched whine that reminded me of a geared motor trying to maintain a rate of revolution but failing and having it spin faster.

In actuality I think it was a case of the motor straining with the load.

#6 Tom Andrews

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Posted 04 October 2012 - 10:32 PM

Upon reflection "run away motor" was the wrong choice of words. What I was trying to describe was a straining motor. As it approached zenith it would race up to a high pitched whine that reminded me of a geared motor trying to maintain a rate of revolution but failing and having it spin faster.

In actuality I think it was a case of the motor straining with the load.


Sounds like balancing to me as well. I've been using that setup for 3 years now and no problems. There are vibrations which would be a frustration for those who are used to none. For me, it's completely usable.

#7 JS999R

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Posted 05 October 2012 - 02:43 AM

I've been using my CG5GT with two 6" refractors weighing in at about 25-26 lbs. I have the Orion pier extension. For visual use the mount is capable, except for a couple times, my GoTos and tracking has been very good. However, I really think the combination isn't the ideal match up, the CGEM mount would offer a better margin of performance since my total weight certainly pushes the mount's limit. It always sounds like the mount is straining. Maybe its not according to Celestron offering for sale the C11 CG5GT combo and in that case the C11 alone weighs in even more than what I have. The OTA is listed at 27.5 lbs, add to that a big 2" EP and your approaching 30 lbs. With a weight limit of 35 lbs and assuming this is accurate, I personally think even my set up is too heavy for the mount.

The pier extension really helped because as stated there is no need to extend the legs. I did it once to look over a backyard obstruction and the subsequent vibrations were hard to accept, not even close to being OK. I installed the pier for another reason, one refractor was so long it came into contact with the tripod legs while near zenith. The pier prevented this from happening again.

The current set up works, but eventually I would like to move up to a CGEM, I think that is a much better fit. I wonder as well with the heavy weight how this will play on the longevity of the mount over time.

I agree with the OP's assessment.

#8 dr.who

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Posted 15 October 2012 - 12:51 PM

There is an old Irish saying (well actually I think it's Italian but since I am Irish it's now an Irish one ;) ) that goes "Better a red face now than a white face later!"... And boy is my face red right now! :lol:

I was mulling over why the C11 on a CG5 combo worked for others but not for me and, being an Engineer aka an** retentive and obsessive ADD, decided that the only way to resolve the issue was to test it again! Turns out that my initial report was not... ah... correct... :lol:

It all came down to balance. I realized that the first time out I had balanced the scope without taking the front cover off and without the full EP train installed which means that my balance was actually off. I realized this because when I went to balance it last night I did the same thing but realized it and RE-BALANCED it correctly this time! :lol:

With proper balance the GOTO's were progressively better on the alignment starting out with Vega (the first star and yes I know at near zenith but it was what the CG5 wanted and it was an easy starting point ;) ) a good 5-6 degrees out of the finder (I also mounted my laser pointer[1] on the OTA so I could better move the scope to where I wanted via Mark I Mod 0 eyeball) but after that Algenib was within the finder scope but on the outside, then Mirach was about halfway from the edge, and Alkaid was darn near center as was Kocab. And I on the last two I was able to leave the 12mm reticule EP in the diagonal instead of having to go between the 40mm and the 12.

After that the actual GOTO's were pretty good. I think it was more a factor that I rushed the alignment and didn't get the alignment stars "perfectly" in the reticule using the up/right method like I usually do. But everything I pointed at was within the 1/4 to 1/2 way point from edge to dead center in an 11mm 82* ES EP.

Sadly of course the C11 even with 30+ minutes under the Cat Cooler, being outside for over an hour, and everything else still had mushy views and everything I looked at really was better (slightly fuzzy) under the 18mm 82* ES and more fuzzy but tolerable with the 14mm ES 82*. I did get a good (as in size) view of the Cat's Eye and saw a blue color to it and Andromeda was bigger but still a fuzz ball so there was some fun. I also did a few splits on Delta Boo and Psi Boo. The C11 worked really well for this and I was able to see the doubles with at least a mm of separation in the 18mm ep. I am new to the whole double star splitting game so please understand that for me it was pretty cool just to see them and I wasn't worried about airy disk etc...

Vibration on a hard surface without anti vibration pads was murder and I really need to invest in a feathertouch or crayford focuser since the stock focuser it a real PITA to use with all the bouncing that occurs.

I also had a bit of a scare in that my son came out and said "What is that burning smell?" followed up with "it smells like beans" to my inquiry about what kind of burning smell... I didn't smell it but was worried that I may have been burning out motors since the mount did strain a bit moving the OTA around though all in all it did a Yeoman's job of slinging that BUFF (Big Ugly Fat F***) OTA around. ;)

So bottom line thumbs up to a C11 on a CG5 with vibration pads for visual only! So much so that I am giving serious thought to purchasing another one so that I can setup the ES 127 on one and the C11 on the other instead of the CGEM. It would be faster, lighter, and easier to move around that way so for outreach and just my own viewing where I set them both up, align them, then set the Cat to the side with the cooler installed for the better part of an hour and a half and view with the 127 until the big gun is properly dressed and trained out to receive visitors.

[1] :graduate: Pro Tip: If you loose the set screw and ring to turn the button on your laser that comes with the Orion (and I assume others) laser pointer holder never fear. A 1/2" hose clamp properly tensioned so that it will just slip on and off the button thus turning it on and off by sliding it up and down the neck is a simple $0.85 cent replacement for a, I am sure, $20,000 (based on prices for astronomy gear) replacement part.

#9 jchoy46

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Posted 16 October 2012 - 06:30 AM

thanks now im tempted again to reconsider deforking my lx200r and using it on my cg5. My only concern is will I still be able to do AP (as bad as I do already).

#10 dr.who

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Posted 16 October 2012 - 12:33 PM

Depending on the size of the LX200 I would say no to the AP on the CG5 with the LX200r. If it is an 8" SCT or bigger for sure no.

#11 rmollise

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Posted 16 October 2012 - 02:48 PM

Depending on the size of the LX200 I would say no to the AP on the CG5 with the LX200r. If it is an 8" SCT or bigger for sure no.


Not really. I have done considerable imaging with an 8-inch SCT on the CG5 with good results... ;)

#12 dr.who

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Posted 16 October 2012 - 03:10 PM

With all due respect Rod, you are one of the Senior Demi Gods of Astronomy and thus could probably make Hubble quality photos with a Celestron Firstscope! :lol:

Seriously though you are one of the one's who "wrote the book" on the subject and I have a great deal of respect for you. So... An 8" on there? Wow! That is pretty darn slick! I did the weight calc added in the extra kit and thought it would be a push... Good to know!

#13 rmollise

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Posted 16 October 2012 - 05:27 PM

I am HARDLY a demi-god when it comes to imaging. More like a Murphy-plagued Gilligan. :lol:

#14 dr.who

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Posted 16 October 2012 - 11:28 PM

...

#15 jchoy46

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Posted 17 October 2012 - 06:19 AM

its a 10 inch and i thought rod could do his sorcery and make magic happen. lol

#16 dr.who

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Posted 17 October 2012 - 10:21 AM

Cheers. The worst you can do is try it and see. It's still a banging good mount regardless and you could always use it for visual and then swap it out with a smaller refractor for AP...

As to Rod... As I understand it Casa del Rod is where dreams come true and the magic happens! :lol: Sorry Rod but I do have to give you a bit of the razz because you are pretty darn famous and all.

#17 rmollise

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Posted 17 October 2012 - 11:45 AM

Sorry Rod but I do have to give you a bit of the razz because you are pretty darn famous and all.


If I'm so famous, why ain't I rich?! :scratchhead: :lol:

#18 jchoy46

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Posted 17 October 2012 - 03:32 PM

prolly cause you keep buying new equipment....

#19 rmollise

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Posted 18 October 2012 - 06:43 AM

I wish! :lol:






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