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hickeydp
member
Reged: 06/14/09
Posts: 91
Loc: Ireland
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Looking for advice as usual...
I'm thinking about purchasing one of these mounts for AP but am unfamiliar with both. The CGE is second hand so will be around the same price for a new CGEM (plus a little I would imagine). It will be throwing around up to 40 pounds.
Interested to hear your opinions...
BTW, the CGEM has a capacity of 40 pounds, what is the capacity of the CGE?
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Clear skies
Damien
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Meade LX200 10 Classic (Deforked on an EQ6)
Meade LXD75 6N AT
Celestron Orange Tube C8 (81)
Celestron C6 (RIP) CG5
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gary-sue69
super member
Reged: 07/19/07
Posts: 177
Loc: Maybee MI.
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go with the cge 60 pounds
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CPC 1100 GPS Schmidt-Cassegrain (StarBright XLT)
Explore Scientific 127 Air-Spaced Triplet APO
Mallincam Color Hyper Plus
CGE Computerized Mount
Orion Awesome Autoguider Refractor Package
Starry Night BlueStar Adapter
Orion Star Target Constellation & Celestial Object Finder
Starry Night Pro Plus 6.2
StarShoot Solar System Color Imager III
Orion StarShoot II DeepSpace CCD Camera
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Luigi
Post Laureate
Reged: 07/03/07
Posts: 4947
Loc: MA
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The CGE is the next class up from a CGEM and will perform better.
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17.5" f/5 Dob. IM-715 MCT. 120ED. Lunt 60mm Ha.
Zeiss, Leica, Fujinon, Nikon, Pentax, Bushnell bins
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mclewis1
Thread Killer
Reged: 02/25/06
Posts: 3961
Loc: New Brunswick, Canada
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CGE vs. CGEM
50% more capacity, heavier bearings and 1.25" cw shaft
Heavier tripod (2.5" legs)
Less ability to image past the meridian ... the CGE hardware gets in the way sooner (there are bumpers preventing damage if you drive them together)
Home position switches - the hardware dictates where home is
Same hand controller (HC), same functions if you upgrade to the latest firmware (www.nexstarsite.com for info) ... make sure the CGE HC is an upgradable model (at least v4.1x firmware) otherwise you'll likely have to buy a new HC.
On a used CGE I'd check very carefully for runaway slew problems caused by the RA and DEC cables. This is a known area of concern on all CGEs, the fix before any hardware problems with the RJ45 sockets shows up is to replace the cables with more flexible ones - look up "Marty cables" from VPI here on CN. If the sockets have become a problem (multiple new cables have been used and the problems still occasionally show up) then some additional measures are required to re establish a solid connection between the shell on the connector and the socket .. this can be as simple as some foil added in the socket or may require re soldering the connector wires.
Assuming you are ok with the overall weight of the CGE and with 40lbs of imaging gear I'd go with the CGE if you can verify that it's a good used model. I'd replace the RA and DEC cables with the "Marty" VPI cables (they are very inexpensive) and spend some time adjusting and lubing the RA worm to remove any backlash. Oh and make sure you get enough counterweights ... the single 25lb one is not going to be enough ... the CWs for the CGE are the same as those used on the Losmandy G11.
The Yahoo Group CGE uncensored is a great source of background info on the mount.
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Mark
C11, C6, APM/TMB115, and AT80ED - Tandem mount CGE and CG-5A, WO EZ-Touch and AT Voyager
25x100s and 8x56s, T-Mount Light, Mark 1 eyeballs - Modded 350D, DSI-P, SPC900, Mallincam
Just because you can doesn't necessarily mean that you should
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jason_milani
Carpal Tunnel
Reged: 09/03/04
Posts: 1737
Loc: Northeast Ohio
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What Mark said. 
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Celestron C-14
Celestron C-8
Celestron C-5
Orion/Vixen ED114SS APO
William Optics Megrez 72mm ED
Celestron CGE mount
Discmount DM-4
Mallincam Hyper Color Plus
Baader UV/IR Modded Canon 40D
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CounterWeight
Pooh-Bah
Reged: 10/05/08
Posts: 1305
Loc: PDX chronoplast
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Although I don't have a CGEM I do have a CGE and will say following from experience... in addition to what others have said here...
The allen wrench adjustments doing a PA are a royal pain, definately do-able, but just an all around PITA.
With 23lbs and over SCT or refractor, the PA will move when tightening the various tension knobs and screws, so you need to do this carefully, it's darn near an art form. 40lbs and above the (seems to me) the 2 half moon uprights that hold the mount to the pier are not sufficient and there is some slop and again an art for to tighten the two tension hex's for this withought getting significant drift. (This this the 40+lbs heeled over on the cal star, Polaris or otherwise) After 9 months of this I'll say it can be done but a good PA can take much more time than you think need be because of the above mentioned.
I think my TEC APO160ED taxes this thing to the limit even though it is essentially same weight as a TOA 130.
With legs extended to max the OTA will still smack the mount legs easily using my 160 and the SSP v2, and on some nights an some objects makes near meridian imaging impossible - so a pier extension may be required depending on your OTA length...
The RA and DEC interconnect cables are one problem, and so are their 'female' connectors (I'll be posting about this later today)
The limit switches can also cause problems in both the RA assy (two here) and DEc assy (thankfully only one)
CGE Tripod...
Clamps for tripod legs are inadeguate and if you extend the legs I recommend adding some inexpensive pipe clamps to the necessary list, (after levelling the mount)attach to smaller diameter leg when extended just beneath exit from larger, tighten securely. This in addition to tightening the T-handle clamps on the legs.
Make sure the CGE mount has the metal lower spreader plate and NOT the plastic one which can fail (catastrophically).
Make sure the leg clamps on the spreader arms are secure otherwise will 'ride up' from intended position just above leg extensions..
Lasly here - the power connector, if you can find a right angle adaptor (I think shoestring used to sell one) beware - I did break mine.
OK, thats all just hardware stuff.
As far as the mount performance and accuracy once aligned and PA'd - performance is fantastic! Centering on the chip not unusual  for AP work. I've gone 12 minute guided no problem! (unfortunately my LP is a huge problem) For a night of visual observing, you are set.
Going 420/480 second exposures all night no problem, see my image gallery for some results.
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- 
CGE (Frankenmount mod.)
Onyx 80ED, Tak FS-128 #02058, TEC APO160ED #030
CCD: Orion SSPDSCIv2, SSI3, SSAG
diags, ep's, tubes, filters, Binocs
My CN Image Gallery
Experience is a difficult teacher, it gives the test first, and gives the lesson later
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hickeydp
member
Reged: 06/14/09
Posts: 91
Loc: Ireland
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... beginning to think I should add, or Losmandy G11 to the options
thanks for all your input, much appreciated
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Clear skies
Damien
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Meade LX200 10 Classic (Deforked on an EQ6)
Meade LXD75 6N AT
Celestron Orange Tube C8 (81)
Celestron C6 (RIP) CG5
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Ian Robinson
Pooh-Bah
Reged: 01/29/09
Posts: 1166
Loc: Gateshead.NSW Nth Coast,Austra...
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Go for the more capable GEM (that will be the secondhand CGE).It's a no brainer when the choice is G11 , CGEM or CGE.
My choice was similar about 12 months ago, I decided to take a quantum leap up and bought a Vixen New Atlux (I got great deal that brought this mount into a range I was prepared to pay, the near parity of tbe $AU witn the $US at the time helped too).
Don't limit yourself to american brandnames.
Edited by Ian Robinson (08/06/09 05:58 AM)
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Alph
sage
Reged: 11/23/06
Posts: 261
Loc: Melmac
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Quote:
.. beginning to think I should add, or Losmandy G11 to the options
Good thinking. It is more portable (lighter) than the CGE and it has a lower and smoother PEC. If you are not located in the US, don't buy Celestron mounts. Self-Servicibility is a big problem with Celestron mounts.
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Taylor
professor emeritus
Reged: 07/10/05
Posts: 558
Loc: Federal Way, WA
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Doesn't the Vixen SXD has a similar payload capacity to the CGEM?
Vixen's are known for low periodic error compared to Celestron's, which is great for Astrophotography.
Another good bet is the Atlux like someone else mentioned here.
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Some OTAs, a mount, some eyepieces, and some cameras
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mclewis1
Thread Killer
Reged: 02/25/06
Posts: 3961
Loc: New Brunswick, Canada
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Quote:
Doesn't the Vixen SXD has a similar payload capacity to the CGEM?
Um, no it doesn't. The published payload is 50lbs which includes the counterweights. The SXD equipment only capacity is something like 30lbs or so ... half that of the CGE.
Quote:
Vixen's are known for low periodic error compared to Celestron's, which is great for Astrophotography.
Really? Where is that published ... and I don't mean one particular mount but an average of what the mounts generally really deliver. If you want to compare individual mounts I know of a few CGEs that show raw PEs of well under 10 arc/s peak to peak and when corrected with PEC down around 2 arc/s. In general out of the box CGEs will usually be somewhere between 10-20 arc/s (anecdotal data gathered from 10-15 users over the past couple of years and this generally correlates well with what is posted here and on Yahoo/groups).
Another good bet is the Atlux like someone else mentioned here.
Yes it's a nice mount, but not quite a CGE. It's on quite a bit smaller tripod and has only 2/3rds the carrying capacity of the CGE (75lbs total including counterweights).
The CGE can carry 60-65lbs of equipment for visual work so it's total carrying capacity (measured like Vixen does) is over 100lbs.
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Mark
C11, C6, APM/TMB115, and AT80ED - Tandem mount CGE and CG-5A, WO EZ-Touch and AT Voyager
25x100s and 8x56s, T-Mount Light, Mark 1 eyeballs - Modded 350D, DSI-P, SPC900, Mallincam
Just because you can doesn't necessarily mean that you should
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Taylor
professor emeritus
Reged: 07/10/05
Posts: 558
Loc: Federal Way, WA
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Quote:
Um, no it doesn't. The published payload is 50lbs which includes the counterweights. The SXD equipment only capacity is something like 30lbs or so ... half that of the CGE.
Um, of course the SXD has half the capacity of the CGE, notice in my post I only mentioned the CGEM. SXD is ~30 lbs, and most image with the CGEM at 35 lbs, some go for 40 lbs, keyword is similar.
Now relax, I'm not knocking Celestron's, why would I? I am buying a CGEM next week. They're excellent mounts.
Of course the CGE is going to have very low PE, its a high end mount with that purpose in its design. With a little tweaking/guiding I'd expect it to have <4arcs peak to peak, its a great mount.
The CGEM however is manufactured in China, most likely in the same factory as all other EQ6 based mounts, and has raw PE similar to them, in the order of 50-60 arcs peak to peak. Granted, they have excellent software that allows anyone to guide it out with PhD, PEMPro, etc.
See the last graph, the CGEM PE can almost be completely guided out, making it completely suitable.
Quote:
Really? Where is that published ... and I don't mean one particular mount but an average of what the mounts generally really deliver. If you want to compare individual mounts I know of a few CGEs that show raw PEs of well under 10 arc/s peak to peak and when corrected with PEC down around 2 arc/s. In general out of the box CGEs will usually be somewhere between 10-20 arc/s (anecdotal data gathered from 10-15 users over the past couple of years and this generally correlates well with what is posted here and on Yahoo/groups).
Another good bet is the Atlux like someone else mentioned here.
Here ya go:
Vixen's:
GP-DX, SSPC2k v2.40, no PEC, no guiding, 10 minutes, ~20arcs peak to peak:
SXD from an owner on Yahoo Sphinx group:
Atlux, revision 4.04v18, no PEC, no guiding, ~16-17arcs peak to peak:
CGE, 2005 revision, don't know software on it, ~26-27 arcs peak to peak:
Raw EQ6 w/ no computer (CGEM based on these components), >40arcs peak to peak:
And here, to prove any mount's error can be guided out using PhD, CGEM showing <5arcs peak to peak, excellent:
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Some OTAs, a mount, some eyepieces, and some cameras
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hydroman3
newbie
Reged: 08/06/09
Posts: 1
Loc: Western MA
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I've also found the furnished allen wrenches to be nearly impossible to use. Go to Sears or any good tool store and get a set of T handle allen wrenches. They are straight about 6 or so inches long with a T handle on one end to grip with your hand. They work great for making PA adjustments.
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Alph
sage
Reged: 11/23/06
Posts: 261
Loc: Melmac
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Quote:
out of the box CGEs
Yeah right. Any suggestions how to reduce CGE PEC - marty cables?
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Ian Robinson
Pooh-Bah
Reged: 01/29/09
Posts: 1166
Loc: Gateshead.NSW Nth Coast,Austra...
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Quote:
Quote:
Um, no it doesn't. The published payload is 50lbs which includes the counterweights. The SXD equipment only capacity is something like 30lbs or so ... half that of the CGE.
etc etc
One of biggest reasons I bought my New Atlux was the very low PE c/f other "similar" level mounts. For wide field imaging I expect once I've tuned the PEC , I'll be able to get away without autoguiding without getting noticeably eggy stars + it has better performance in other areas too as wall as better capacity.
PE less than 1/2 that of a tuned (upgraded I believe) CGE is nothing to thumb your nose at.
Was a very close thing for me , I was ready to buy a CGE until I got a great offer for one of the first New Atluxs coming to Australia (so I got an Atlux instead).
Losmandy mounts weren't in the same ball park no matter how they are "enhanced" aftermarket.... and I didn't want to ship an Losmandy GEM back to the USA to be "enhanced" / tuned .... kinda defeats the purpose of buying the mount here (in Oz).
(And I've wanted an Atlux for many years based on the rave reviews I seen of it over many years... ).
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mclewis1
Thread Killer
Reged: 02/25/06
Posts: 3961
Loc: New Brunswick, Canada
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Quote:
Um, of course the SXD has half the capacity of the CGE, notice in my post I only mentioned the CGEM. SXD is ~30 lbs, and most image with the CGEM at 35 lbs, some go for 40 lbs, keyword is similar.
Taylor ... my appologies, but for some strange reason your post (and a few others) originally had ? characters in place of a few regular characters on my PC, one of which was the M in CGEM ... going back and looking at the posts they now look fine. Very strange. I also didn't notice that when I quoted your post that the characters showed up normally.
Quote:
See the last graph, the CGEM PE can almost be completely guided out, making it completely suitable.
I agree, and this is generally the same for most of today's mounts regardless of who makes them. Advances in autoguiding today are making most mounts look great and giving folks lots of less expensive options for imaging.
I had a feeling that you'd quote that French site, that's why I made the comment about individual mounts. It is exceptionally difficult to get an accurate understanding of what the average PE will be for most mounts today, with most of the information available being from only a few examples measured. Plus even when you do get to see some data there are other variables to consider, such as how the PE is measured or changes between the various types of measurement software, and how the results are displayed. The mounts themselves even change over time as the manufacturers make production changes, this can be seen in the CGE graph ... it's a pre 2006 model and the CGE's shipped since tend to show a somewhat smoother PE (again anecdotal info based on comments from Yahoo/Groups). Then there are all the tweaks and upgrades that can be done to a mount, sometimes those will be disclosed, sometimes not. Therefore with all the variables it can get a bit dangerous making statements about one mount being better than another based upon PE measurements from only a few examples.
There have unfortunately been some other folks around here who've consistently thrown rocks at CGEs and I get a little defensive when I see some of those generalizations.
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Mark
C11, C6, APM/TMB115, and AT80ED - Tandem mount CGE and CG-5A, WO EZ-Touch and AT Voyager
25x100s and 8x56s, T-Mount Light, Mark 1 eyeballs - Modded 350D, DSI-P, SPC900, Mallincam
Just because you can doesn't necessarily mean that you should
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freestar8n
sage
Reged: 10/12/07
Posts: 301
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I never really understood this focus on PE. The dominant periodic terms tend to be large but slow, and are largely removed after applying PEC. If you aren't autoguding you should use PEC, so the relevant measure isn't just PE, but the residual error after applying PEC. If you *are* autoguiding, I still recommend using PEC and the relevant thing is all the terms left over that are above, say 1", and how fast they move - not how big they are. Many of those terms are either too fast or not commensurate with the worm period and cannot be removed by PEC.
Celestron mounts can use the free PECTool to average multiple PE cycles and upload them to the mount. For my cge, this works well to remove the fundamental and harmonics. I average 8-10 worm periods while autoguiding to record the PEC curves. After applying PEC, I chase the residual stuff with 1 second guide corrections.
I use an early cge with its original worm/wheel and even the original ra/dec. cables. It has never been sent for service, but I have overhauled and tuned it myself using helpful guides in CN and elsewhere. Examples of my images with this old thing at 0.5-0.8" per pixel with C11 are here.
Frank
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David Pavlich
Postmaster
Reged: 05/18/05
Posts: 8687
Loc: Mandeville, LA USA 30.22 X 90....
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Quote:
Quote:
out of the box CGEs
Yeah right. Any suggestions how to reduce CGE PEC - marty cables?
Send it to Doc Clay.
David
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Proud Member; PAS NOLA,
"If we knew what we were doing, it wouldn't be called research..."
A. Einstein
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Alph
sage
Reged: 11/23/06
Posts: 261
Loc: Melmac
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Quote:
Send it to Doc Clay
Thank you, but no, thank you. How is he going to do that, any details, facts, before and after PEC curves? Show me hard evidence that his service can substantially reduce PEC. Don’t tell me ‘it worked for me’. PEC is built into the worm. Does Doc Clay rebuild the worm? Adjusting worm – gear gap is a trivial task. Lapping the worm and gears by slewing is also a very simple task. These ‘cures’ might make the PEC curve a bit smoother. It will not be a dramatic change though. Been there, done it.
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Taylor
professor emeritus
Reged: 07/10/05
Posts: 558
Loc: Federal Way, WA
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To Damien,
What optical tube and cameras/guide are you mounting on it?
Do you have equipment that warrants a 60lb CGE or would 40lb CGEM suffice?
If your budget is for a new CGEM and you would only need the 40 lb capacity, that would probably be your best bet as long as Celestron warranty service is good in the UK. I've seen several people sending theirs back for repair after they bought it. Or if there is a reputable dealer near you that is willing to let you open one up and make sure it is satisfactory before you take it home.
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Some OTAs, a mount, some eyepieces, and some cameras
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