Author Topic: Sky Watcher EQ6 vs. Celestron CGEM  (Read 1111 times)

Eric Curry

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Sky Watcher EQ6 vs. Celestron CGEM
« on: December 24, 2017, 05:52:28 PM »
Has anyone had experience with both of these mounts, or even more especially using the SW EQ6?  I can not find any user reviews of the SW.  They look comparable with the exception that the SW has a polar alignment scope.



Phil Barela

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #1 on: December 27, 2017, 12:05:36 AM »
The CGEM also includes a polar alignment scope (as an accessory).
I haven't compared them.  I am told they are automatically very similar.

knucareaslo

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #2 on: December 29, 2017, 01:54:03 PM »
Hmmm...

Good question. Same tripod, same rated capacity, same hand controller hardware, both are motor control only, same price (polar scope excepted). A polar scope is pretty much essential for photography but you can do without for visual. The Celestron is prettier, the Sky-Watched more utilitarian.

I must say that I grew quite fond of the white HEQ5 I have. White paint makes it a tad bit more user friendly in the dark. I suspect it's a matter of preference, both are likely made in the same factory! Have fun shopping.

--Christian

Tom Doyle

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #3 on: December 30, 2017, 08:54:59 AM »
Yes, same manufacturer (Synta).
The CGEM has computer-aided All Star Polar Alignment (ASPA). You don't have to have a polar scope or even be able to see Polaris. You get greater accuracy than with a polar scope.
I am not sure whether the EQ6 has that feature. It may.

I am told that the CGEM has servo motors and the EQ6 has stepper motors. Personally, I trust servos more, but that is not from recent experience; both are probably quite reliable now.

I am also told that the CGEM hand controller and firmware are more full-featured. Can someone confirm this?
Finally, the CGEM has the 8/3 periodic error problem: Its periodic error cannot be completely corrected by PEC because there is a periodicity in it that is longer than one revolution of the worm. That is noticed only by people who measure and analyze autoguider graphs. The AVX lacks it, which is one of the advantages of the AVX (a much lighter weight mount).

David Corder

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #4 on: December 31, 2017, 10:19:23 AM »
I noticed, Michael C., that you have an 8" EdgeHD, ostensibly on an AVX GEM. How is that working for you? That OTA is the one I'm considering (currently--my interest changes daily, it seems), but was thinking of buying it on the CGEM instead in order to accommodate a heavier astrographic newt or larger refractor down the road.  The consensus seems to be that both the WS EQ6 and the CGEM are the same basic mount, so perhaps the savings of buying the OTA and the CGEM together make sense.

imasatex

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #5 on: December 31, 2017, 04:22:32 PM »
The CGEM and EQ6 are similar in some ways but quite different in others.

The hand controllers and electronics are completely different. The CGEM uses the Celestron NexStar system while the EQ6 uses SkyWatcher's SynScan controller. Both have their quirks and both have their strengths, but they are totally different animals and share no parts or common code (as far as I can tell).

Also, the CGEM uses servo motors while the EQ6 uses stepper motors. The motor driver boards are also different due to the different types of motors. Both are reliable. The EQ6 is generally quieter.

Both have polar alignment routines. Don't know which is better. Might be a wash. The EQ6 can get you to one arc-minute of the pole usually. Not sure how accurate theCGEMis, butthe ASPA seemswell-regarded.

Of the two, I prefer the EQ6 because (IMHO) its a better platform for imaging. But the CGEM generally has better goto accuracy due to its 2+4 alignment algorithm. Not an issue for me though, the EQ6 supports EQMOD which is also very accurate. There's more but I have to run so...

Mark Rivera

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #6 on: December 31, 2017, 05:42:00 PM »
I've seen this conversation multiple times on Cloudy Nights. I still love looking at what people have to say because i'm still considering both as well. I think you are in the same decision process as I am. I've ruled out the iOptron IEQ45 because it seems every forum out there from CN to Stargazers lounge, etc shows it having issues (sorry iOptron folks  ). For an under $2,000 mount I don't think you can go wrong either way. I'm no expert but with me posting similar things about my decision process i've run across the following themes:

-Both are made by Synta. The CGEM has servo motors and the EQ6 has Steppers. In the past steppers had more longevity than servos, but nowadays either is fine
-Both have trouble with the supplied altitude adjustment bolt. It's better just to buy the ADM alt bolt when you buy the mount (whichever one)
-Celestron pushes more frequent updates for the Nexstar hand controller than Skywatcher does for Synscan
-Both mounts have a multi-star alignment routine. Its just somewhat easier as in the step by step of the CGEM ASPA
-Skywatcher is trying to grow into the US market. They are very popular in Canada already. Skywatcher USA has good follow up from web inquiries (in my opinion)
-The Skywatcher is currently priced a little lower than the CelestronAlso you mentioned there being a large void of reviews for the EQ6. The Orion Atlas is exactly the same and there are lots of reviews online for the Atlas. Its the same exact mount as the EQ6, just relabeled and different colorhttp://www.telescope...379/p/24338.uts

but normally the Orion Synta rebrands are anywhere from $100-200 more expensive than Skywatcher

Roberto Betancourt

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #7 on: January 05, 2018, 04:18:50 PM »
Ok, I'm back. Other differences I can remember off-hand are:

The EQ6 comes with a polar scope and GPS unit. These are available for the CGEM as well, but they are extras and do not ship with the mount. (at least 2yrs ago they didn't, maybe they do now but I don't think so).

The counterweight shaft on the EQ6 slides into the head when not used. The CGEM counterweight shaft unscrews and is a separate part when transported. Some folks complain about the shaft on the EQ6 being too small of a diameter for the weight it carries. Its a bit springy for sure. I don't know how the base CGEM compares this way, but I do know that the CGEM-DX version has a much beefier counterweight shaft and supports the 10kg (22lb) counterweights. (The DX also has a mighty tripod, much bigger than the EQ6 and regular CGEM).

The castings for the heads are different. The EQ6 head is an older design and it also includes setting circles. The CGEM is a more modern design and does not include setting circles. In actual use, the setting circles are not needed and so are redundant on the EQ6.

The EQ6 saddles can accommodate Vixen and Losmandy dovetails. I think the CGEM only supports the larger Losmandy size - CGEM owners: please correct me if I'm wrong on this one.

The EQ6 can be (and often is) belt modded to help smooth out the tracking. I've done mine and it has improved things a lot. (PE is the same though, its just a lot smoother during the period cycle now and much easier to guide as a result). I have not heard of a belt mod for the CGEM, although there may be one out there somewhere.

Some similarities are:

I've read that both use the same worm gear and ring (hub) assembly.

Both have PEC, but the CGEM is permanent. The EQ6 is not (it needs to be trained for each session).

Both use multiple bearings on each axis, including the DEC assembly. (as opposed tosay, the AVX, which does not have full bearings on DEC or so I've heard).

Both have approximately the same payload capacity of around 40lbs. Actual max payload will vary depending on length of scope and mostly the user expectations forimaging.For visual use I have seen that they both work well up to about 40lbs. Can't say about the CGEM but the EQ6 is good for imaging up to around 25-30lbs or so (again depending on the actual scope and accessories used).

Both have a tour function built into the hand controller. The CGEM tour isbetter though, its well organized (less wasted motion) and has more items.

That's all I can think of for now. Hopefully enough to help make things even more confusing... Happy shopping!

Eric Hayes

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #8 on: January 08, 2018, 01:17:35 PM »
Quote
I noticed, Michael C., that you have an 8" EdgeHD, ostensibly on an AVX GEM. How is that working for you? That OTA is the one I'm considering (currently--my interest changes daily, it seems), but was thinking of buying it on the CGEM instead in order to accommodate a heavier astrographic newt or larger refractor down the road.  The consensus seems to be that both the WS EQ6 and the CGEM are the same basic mount, so perhaps the savings of buying the OTA and the CGEM together make sense.


I bought the AVX because a rib injury prevented me from handling anything heavier at the time. Now that I'm better, I'm evaluating a friend's CGEM and thinking of purchasing it or something in its class.

The AVX is fine for visual work, for lunar and planetary video, and for carrying my 300-mm telephoto lens without a telescope. It's not quite up to carrying my entire astrophoto setup (C8 EdgeHD, compressor, camera, guidescope, and guide camera), which weighs over 25 pounds; the symptom is that the RA tracking becomes somewhat rough at the arc-second level.
The AVX is certainly nice to have because it's so lightweight. If I owned both mounts, I would use the AVX for everything except deep-sky photography through the telescope. The CGEM would also open up the possibility of heavier telescopes later.

Note that they have different dovetails. The AVX uses a Vixen (V) dovetail and the CGEM uses a Losmandy (D) dovetail. Adapters and dual saddles are available.

coatiorachin

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #9 on: January 08, 2018, 08:54:08 PM »
Quote
Both have polar alignment routines. Don't know which is better. Might be a wash. The EQ6 can get you to one arc-minute of the pole usually. Not sure how accurate theCGEMis, butthe ASPA seemswell-regarded.

How do you know the EQ6 gets you within 1' of the pole? Subsequent drift method, or is that just what it reports?

With Celestron's ASPA, the accuracy seems to be about 5' or a little better, as confirmed by drift method or by repeating the full alignment process.
Immediately at the end of ASPA it reports zero error because it has no way of knowing otherwise.

Eric Castro

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #10 on: January 09, 2018, 08:30:08 PM »
Quote
Ok, I'm back. Other differences I can remember off-hand are:

The EQ6 comes with a polar scope and GPS unit. These are available for the CGEM as well, but they are extras and do not ship with the mount. (at least 2yrs ago they didn't, maybe they do now but I don't think so).

The counterweight shaft on the EQ6 slides into the head when not used. The CGEM counterweight shaft unscrews and is a separate part when transported. Some folks complain about the shaft on the EQ6 being too small of a diameter for the weight it carries. Its a bit springy for sure. I don't know how the base CGEM compares this way, but I do know that the CGEM-DX version has a much beefier counterweight shaft and supports the 10kg (22lb) counterweights. (The DX also has a mighty tripod, much bigger than the EQ6 and regular CGEM).

The castings for the heads are different. The EQ6 head is an older design and it also includes setting circles. The CGEM is a more modern design and does not include setting circles. In actual use, the setting circles are not needed and so are redundant on the EQ6.

The EQ6 saddles can accommodate Vixen and Losmandy dovetails. I think the CGEM only supports the larger Losmandy size - CGEM owners: please correct me if I'm wrong on this one.

The EQ6 can be (and often is) belt modded to help smooth out the tracking. I've done mine and it has improved things a lot. (PE is the same though, its just a lot smoother during the period cycle now and much easier to guide as a result). I have not heard of a belt mod for the CGEM, although there may be one out there somewhere.

Some similarities are:

I've read that both use the same worm gear and ring (hub) assembly.

Both have PEC, but the CGEM is permanent. The EQ6 is not (it needs to be trained for each session).

Both use multiple bearings on each axis, including the DEC assembly. (as opposed tosay, the AVX, which does not have full bearings on DEC or so I've heard).

Both have approximately the same payload capacity of around 40lbs. Actual max payload will vary depending on length of scope and mostly the user expectations forimaging.For visual use I have seen that they both work well up to about 40lbs. Can't say about the CGEM but the EQ6 is good for imaging up to around 25-30lbs or so (again depending on the actual scope and accessories used).

Both have a tour function built into the hand controller. The CGEM tour isbetter though, its well organized (less wasted motion) and has more items.

That's all I can think of for now. Hopefully enough to help make things even more confusing... Happy shopping!

The GPS module is only available with the EQ6 in Canada. The one supplied by Skywatcher USA does not include the module

Joe Mallard

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #11 on: January 09, 2018, 10:43:49 PM »
Quote
The counterweight shaft on the EQ6 slides into the head when not used. The CGEM counterweight shaft unscrews and is a separate part when transported. Some folks complain about the shaft on the EQ6 being too small of a diameter for the weight it carries. Its a bit springy for sure. I don't know how the base CGEM compares this way, but I do know that the CGEM-DX version has a much beefier counterweight shaft and supports the 10kg (22lb) counterweights. (The DX also has a mighty tripod, much bigger than the EQ6 and regular CGEM).

The EQ6 saddles can accommodate Vixen and Losmandy dovetails. I think the CGEM only supports the larger Losmandy size - CGEM owners: please correct me if I'm wrong on this one.

The EQ6 can be (and often is) belt modded to help smooth out the tracking. I've done mine and it has improved things a lot. (PE is the same though, its just a lot smoother during the period cycle now and much easier to guide as a result). I have not heard of a belt mod for the CGEM, although there may be one out there somewhere.

Both have PEC, but the CGEM is permanent. The EQ6 is not (it needs to be trained for each session).

By those criteria the CGEM is looking better, especially if people have doubts about the counterweight bar on the EQ6.

Lack of permanent PEC on the EQ6 is a show-stopper for me.

Also, the belt mod suggests that the original drive isn't as smooth as the servos in the CGEM.

You're right about the dovetail sizes. ADM makes replacement saddles that take both sizes of dovetail in the same saddle.

loraderclot

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #12 on: January 11, 2018, 02:51:16 AM »
The belt mod for the EQ6 is for eliminating backlash and period error in the intermediate gears between the motor and the worm assembly. (aka the spur gears).

The steppers themselves are quite smooth since the step size is very small. I'm pretty sure the CGEM also has intermediate gears between the motor and wormand as such it will likely have the sameperformance as an un-modded EQ6 in that respect.

The lack of PPEC on the EQ6 is mostly a non-issue for me since the guider takes care of PE quite nicely. PPEC would be nice though and I do wish it had it, if only to cut back on number of pulses needed to keep the guiding on target.

Of the two, I preferred the EQ6 as an imaging platform. I tested a CGEM-DX awhile back because I wanted a mount with a higher payload than the EQ6.In the end the EQ6 performed (tracked) better, even when overloaded. So the CGEM-DX went back and I belt modded the EQ6 instead. It works very well now for my lighter scope. To accommodate my heavier scopes I ended up with an EQ8 -But that's a lot more money so may not be the right decision for everyone.

If I were strictly visual though, I'd probably run a CGEM mostly because the hand controller has more features, is more accurate and has a better tour.

Another alternative is the AZ-EQ6. Its already belt driven and has a number of other improvements over the original EQ6. But that's another thread altogether...

grateganir

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #13 on: January 11, 2018, 06:27:31 AM »
Quote
How do you know the EQ6 gets you within 1' of the pole? Subsequent drift method, or is that just what it reports?

With Celestron's ASPA, the accuracy seems to be about 5' or a little better, as confirmed by drift method or by repeating the full alignment process.
Immediately at the end of ASPA it reports zero error because it has no way of knowing otherwise.

Subsequent drift alignment with PHD2. Usually it takes 2 or 3 iterations of the PA process to get to this. (sometime more).

Lately I've been just using the polar scope and going right to PHD though. No point in doing the PA routine from the hand controller since the PHD routine is quite nice and my polar scope is aligned pretty good. Also, when I run EQMOD I bypassthe hand controller so can't use its PA routine anyway.

EDIT: Yes, I've seen both the EQ6 and EQ8 report zero error as well. But PHD knows better. Also, I've found that the reported PA error depends on the alignment stars selected. If you do the PA based on a 2 stars alignment, then check against 2 different stars, you get a different error value. So, I generally only trust it down to1 arc-minute or so and let PHD do the rest.

knigabretta

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Re: Sky Watcher EQ6 vs. Celestron CGEM
« Reply #14 on: January 11, 2018, 08:07:14 AM »
Quote
The GPS module is only available with the EQ6 in Canada. The one supplied by Skywatcher USA does not include the module


That's unfortunate. The GPS is pretty expensive as an option, even up here if one needs a replacement.