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CGEM vs Atlas EQ-G . . . on the brink . . .

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#1 dawziecat

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Posted 01 November 2010 - 05:40 AM

Getting close to order time . . . VERY close!

Orion is selling the Atlas GoTo for $1249. For how long I don't know. Wouldn't want to miss the sale.

BUT . . . I still have a couple of concerns.

1/ The CGEM can be polar aligned without access to Polaris.
Can the Atlas?
2/ I have a Losmondy type dovetail. Think I will need a new saddle plate like this one.
3/ I will be mounting a C11. Will I need an extra counterweight. It comes with two 11 pounders.

Any advice from Atlas or CGEM owners much appreciated. Reasons for turning this sale down and ponying up $1399 for a CGEM instead would also be appreciated.

#2 mtibor

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Posted 01 November 2010 - 06:28 AM

I just recently got my used Atlas,for polar-alignment you will need Polaris in order to get the polar-alignment done.Don't know anything about the CGEM,but it seems to me the Atlas owners are happy with the mount.I know I am:)
I'm not sure what is the weight of your C11,my 10"Newt is about 30lb.Right now I'm using 32lb.of weight and I can just barely balance it out...

Tibor,

#3 Patrick

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Posted 01 November 2010 - 06:40 AM

Wow, that's a great price for a new Atlas! I think the Celestron All Star Polar Alignment (ASPA) routine is exclusive to Celestron scopes. I took a look at EQMOD which is a third party open source application for driving an Atlas, and didn't see any similar routine for polar aligning an Atlas. There may be some shortcuts for doing it, but the ASPA routine is pretty hard to beat. Others may have more insight on the Atlas than I.

Lots of folks use the Atlas successfully for AP and they have to get their mounts polar aligned somehow. I personally wouldn't buy a mount without the ASPA routine simply because I don't like taking 45 minutes to polar align. It can be quite tiresome.

If the ASPA software sold separately, I'd willing pay $150 for it. :smirk: (How's that for an endorsement?) :grin:

Patrick

#4 RTLR 12

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Posted 01 November 2010 - 06:48 AM

I have had my CGEM for a year now and have had no trouble with it at all. The 'All Star' Alignment is soooooooo much easier than using a polar scope. It's fast and accurate and no realignment needed afterwards. I have no experience with the Atlas, but have heard the only real difference is in the software.
As for you questions;

#1: Yes (just answered that one)
#2: You don't need to change the saddle on the CGEM. It comes with the Losmandy style. (saves $90 to $150)
#3: You will need 2 17lb counterweights.

Stan

#5 rmollise

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Posted 01 November 2010 - 07:01 AM

Getting close to order time . . . VERY close!

Orion is selling the Atlas GoTo for $1249. For how long I don't know. Wouldn't want to miss the sale.

BUT . . . I still have a couple of concerns.

1/ The CGEM can be polar aligned without access to Polaris.
Can the Atlas?
2/ I have a Losmondy type dovetail.


1. There is no built-in polar alignment software in the Atlas or in EQMOD (though it does have a utility to help you with the polar scope). It's polar scope all the way. There are ways to align without Polaris (as in a drift alignment), but some may be rather time consuming.

2. Yes, if you want to mount a Losmandy D equipped scope on the Atlas, you will need a new saddle plate.

3. Yeah, you may need a third weight.

#6 bardo

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Posted 01 November 2010 - 07:34 AM

i dont own one (yet) but im almost certain eqmod for the atlas can walk you through the same process the cgem does. that is if you're going to have a laptop with you.

im going to get a new one sometime in the next few months. but im holding out right now to see some more hard testing on the IEQ45. if it has the PE thats being reported i'll probablly go with that...might be something for you to consider as well.

but if i had to have one now it would be no question about the atlas. its tried and true, solid as a rock in QC and it has eqmod. which has so many goodies.

#7 dawziecat

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Posted 01 November 2010 - 07:36 AM

Many thanks for the timely replies. After due consideration, I find my enthusiasm for the Atlas waning somewhat even considering the sale price.
Aligning without access to Polaris would be very helpful to me as a pesky spruce tree has grown very large and denied me access from about the only site I have left.
No extra saddle cost to accommodate the Losmondy plate is a bonus.
Think I'll go with CGEM and an extra counterweight.

#8 David Pavlich

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Posted 01 November 2010 - 07:51 AM

If you're using this for visual only, you have no need to polar align other than starting with the scope pointing north and that can be done using a compass.

However, for imaging, polar aligning is essential. So....there's something else to consider.

David

#9 mtibor

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Posted 01 November 2010 - 11:27 AM

"I personally wouldn't buy a mount without the ASPA routine simply because I don't like taking 45 minutes to polar align. It can be quite tiresome."

I'm not sure what you talking about here Patrick,the Atlas don't have the so called"ASPA"but once the mount is setup and pointed to north,I do the polar alignment in about 5-6 minutes,using just the "2 star alignment"after that I fire up PHD,and I'm ready to go.Never did "drift align"either.Keep in mind I'm new to the Atlas,just got it(used)a few weeks ago.When you talking 45 minutes for polar alignment,well in 45 minutes I'm done with PA,PHD calibration,and probably another 20 minutes shots are bagged already...
And yes,with the "2 star alignment"I'm guiding" long exposures.I don't really do long-long exposures because the LP and the fast scope I have,but the other night just for the hell of it I let the Atlas go for 10 minutes @1200mm FL
the shot came back perfect as far as the "roundness of the stars"
And I don't have EQMOD or anything,just a plain old ATLAS!
Tibor,

#10 j.w.white

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Posted 01 November 2010 - 01:23 PM

AstroPlanner has a function that is very much like Celestron's ASPA called Iterative Polar Alignment. It of course requires a laptop, but if you are running EQMOD then that requirement is taken care of. PEMPro is another option for PA.

#11 Patrick

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Posted 01 November 2010 - 01:45 PM

I'm not sure what you talking about here Patrick



I'm talking about the time it takes to polar align a scope without being able to see Polaris. If you can see Polaris and have a decent polar alignment scope, then it's fairly straight forward to get a half way decent polar alignment starting out. If you can't see Polaris, then you're forced into some kind of iterative alignment procedure which can be time consuming. The OP stated he did not have ready access to Polaris.

I'm not knocking the Atlas because it's a very nice mount. The CGEM is essentially the same mount, but comes with a more robust hand controller and the Celestron firmware.

Patrick

#12 Skylook123

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Posted 01 November 2010 - 01:47 PM

EQMOD needs a six star alignment (three on one side of the meridian, then three on the opposite side) to give the user an assessment of the polar alignment. It will return and azimuth and elevation adjustment amount, but the devil is in how to measure the angular movement, especially in azimuth. Way too much time at public events where I set up, so I do it the old fashioned way.

Since I use my Atlas in a different location for each setup (3-5 times a month for public outreach, usually at schools), I have to polar align every time and it goes fairly quickly. I just align the tripod with a good compass and bullseye level, put on the mount head, CWs, and OTA, then do a 1-star align. Do a GOTO Polaris, and adjust out half of the offset with the mount mechanical adjustments. Last night, for Halloween, I was within 1/2 degree of polar aligned right out of the box because I didn't have a crowd wanting to look. I started on Jupiter with no alignment, after about an hour there was no one standing in line so I aligned on Schedar in Cassiopeia and did a GOTO Polaris and it was on the edge of the inner circle of the Telrad. I did a two star alignment and was on The Owl within five minutes of starting the polar alignment.

There is a BIG trick in getting it nailed down so well at the start. During daylight, I set a good home position; tripod level and North pointing, after adding the mount head and CWs set the latitude in the saddle plate using a cheap inclinometer, add the OTA, roll the OTA until the CW shaft is perfectly level using a bullseye level on the side of the mount head and set the RA setting circle to 6, level the OTA in DEC with the level on the side of the tube, set the DEC setting circle to the latitude, roll the OTA vertical to RA = 0 and DEC = 0. Then, the only offset is the true polar offset. The compass, inclinometer, and bubble level really nailed it this time. I went to The Owl, The Ring, The Dumbbell, Jupiter, M13, and The Sculptor galaxy and every one was within 15 arc minutes, easily inside the eyepiece. A good home position to start is gold with this mount, while a bad home position really makes life awfull at the public events.

But, you've GOT to see Polaris.

#13 RTLR 12

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Posted 01 November 2010 - 02:11 PM

Jim,

I use the same procedure to set up my CGEM and have gotten very good and fast at doing so. I find this procedure to be so good that at times I don't need to bother with a polar alignment.

Stan

#14 fetoma

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Posted 01 November 2010 - 03:54 PM

Aligning without access to Polaris would be very helpful to me as a pesky spruce tree has grown very large and denied me access from about the only site I have left.


Can you tie a rope to the top of the tree somehow so you can pull it aside to see Polaris?

#15 rmollise

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Posted 01 November 2010 - 06:38 PM

i dont own one (yet) but im almost certain eqmod for the atlas can walk you through the same process the cgem does. that is if you're going to have a laptop with you.


If you are talking about polar alignment, the answer is no. That was planned for EQMOD at one time, but never completed. Most folks are happy just using the borescope. As an alternative, there is a shareware program, AlignMaster, that can automate the process.

#16 swartzfeger

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Posted 01 November 2010 - 08:02 PM

I've also been considering the Atlas EG-Q vs CGEM and was initially leaning Atlas. But like the OP, the described ASPA feature of the celestron just may seal the deal for me.

#17 dawziecat

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Posted 01 November 2010 - 08:02 PM

Can you tie a rope to the top of the tree somehow so you can pull it aside to see Polaris?


Oh, no! :noway:
It's a sixty footer or so. I did trim the offending branches
years back but it's much worse now. (I'm much worse too . . .no more tree climbing!)

Thanks to all for the many replies. Don't want anyone to feel somehow their ox is getting gored but, so far, seems to me the only advantage to the Atlas over the CGEM is the sale price and that is partially obviated by the need for a saddle adapter to mount my C11 dovetail plate.

The sole disadvantage to the CGEM is it costs a little more but the software offers me an advantage I can use.

The L screws that adjust and hold the PA altitude seem flimsy on the Atlas? The CGEM looks a little more robust in that particular? Is that a fair observation?

#18 jrbarnett

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Posted 01 November 2010 - 08:16 PM

Gee, with the Atlas at $1249 who's going to bother with the Sirius? It's still $1149.

Both mounts have their pluses and minuses. There are multiple threads in this forum outlining and comparing the pros and cons of each mount.

I think the biggest con of the Atlas is relatively primitive firmware with a more limited feature set. The availability of open source EQMOD partially offsets this weakness *if* you don't mind lugging a laptop into the field.

The biggest con of the CGEM is probably a spotty reliability history coupled with declining customer service quality.

I'd search the terms "Atlas" and "CGEM" in this forum and you'll find more than you ever wanted to know regarding how the two mounts compare. :grin:

I should add that I wouldn't be happy with a C11 on either an Atlas or CGEM. The C9.25 is the biggest SCT I'd put on either mount, even for visual use.

Regards,

Jim

#19 swartzfeger

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Posted 02 November 2010 - 12:51 AM

Not sure if this requires a separate thread, so I'm going to just post in here:

Hypertuning: worth it?

The DIY kits are $135/180, the starter service is $315 + shipping and the advanced is $475 + shipping.

Would it be worth just plowing that money into a better mount? I don't see a lot of mounts that are just a notch above the CGEM/EQ-G pricewise, so the hypertuning seems to be an attractive upgrade if it really does offer a significantly smoother/more precise mount.

My only hesitation in getting this is paying $1300 for a mount and then turning around and blowing another couple of hundred on a mount that may be necessary.

#20 j.w.white

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Posted 02 November 2010 - 01:10 AM

"The biggest con of the CGEM is probably a spotty reliability history coupled with declining customer service quality."

Boy, I ABSOLUTELY agree with that statement!!!! I'm in the middle of Hypertuning my CGEM right now because Celestron didn't fix the stiction problem in both RA and DEC axes. I think it will be worth it since the "nominal" amount of extra cash still leaves you far short of what's needed to reach the next level of mount (what I tell myself anyway......).

#21 Pauls72

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Posted 02 November 2010 - 01:40 AM

As has already been stated yes, yes and definitely yes.

I use my C11 on my Atlas for visual all the time and am very happy with it. I have never used the C11 for imaging (yet), only my 8 inch reflector or 102mm Mak. At home, I usually set up on the sidewalk in the yard. It runs north/south and the neighbors big old oak tree blocks Polaris. I do basically the same thing as Skylook123. Here are a couple of tips that may help.

Find a runway map for a nearby airport. It will tell you the difference between magnetic north and true north. Here is one for Halifax, NS. The full arrow points to true north, the half arrow points to magnetic north. The map says the difference was 19 degrees back in 2003 and magnetic moves 8.3 minutes to the east every year. So the current difference is about 18 degrees. Use your compass and point your scope 18 degrees east of magnetic north.

I was cheap and made my inclinometer with a plastic half circle protractor, piece of heavy thread and a fishing weight. Total investment was under a $1.

At the end of a session I make sure and park the mount. I painted some marks on the sidewalk where the three legs go. So next time I bring it out, all I have to do is put the 3 legs on the paint marks, do a quick 2 star alignment and I'm good to go. If you are in the grass or dirt you could bury some bricks or blocks at ground level and make your marks on the bricks.

If I take my C11 & Atlas to an outreach event or star party I have to realign it, but it's no big thing for me.

I bought my Atlas just before the CGEM came out. I do not use EQMOD, but I do use PHD and my laptop to guide when I'm imaging. It's no big thing to have the laptop there, because I need the laptop there anyway to drive the camera. Using the ASCOM drivers for either mount, there are quite a few different PC and MAC programs that will drive either mount and give you some additional functionally. I don't think you would be unhappy with either mount.

Both mounts are rated for 40 lbs. capacity. The C11 weighs 27.5 lbs. Even when you add on an eyepiece, diagonal, Crayford focuser and dew shield you are still only at 32-33 lbs. That's well under the mounts capacity.

That's 33 lbs of counter weights, you will never balance a C11 with only 22 lbs.

Posted Image

#22 Lane

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Posted 02 November 2010 - 03:36 AM

Gee, with the Atlas at $1249 who's going to bother with the Sirius? It's still $1149.


I can answer that - WEIGHT

The Sirius is a small mount and can be moved around fully assembled pretty easily. If all you plan to use is a C8 or 4" refractor and you're not into AP then the Sirius is a better choice. Obviously there are other small mounts that are much less expensive, but their not nearly as nice as the Sirius.

#23 Skylook123

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Posted 02 November 2010 - 05:33 AM

.
.
.
I was cheap and made my inclinometer with a plastic half circle protractor, piece of heavy thread and a fishing weight. Total investment was under a $1.
.
.
.


:lol:

That sure beats my $7 for a Home Depot wall inclinometer!

#24 NewAstronomer

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Posted 02 November 2010 - 08:36 AM

I'd still opt for the Atlas any day of the week and twice on Tuesday. EQMOD is very powerful, and doubly so if you pier/permanent mount. At its current $1249 price its a no brainer. The EQ45 is 22% more expensive, it will hopefully track as well as the Atlas or better, hold as much as a C11 for visual, but weigh more like a Sirius. If those things are true its price is justified.

#25 NeoZavier

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Posted 02 November 2010 - 09:02 AM

I have the CGEM for over 2 months and I don't regret it. is a great mount a friend of mine has the Atlas and the Sirius mount and the difference is not much:
1. The CGEM has faster tracking over the Atlas.
2. The Atlas is a quieter mount because uses stepper motors.
3. The GCEM has All Star Polar Align for visual use.
4. 5. The Atlas has EQMOD a free program that is great!

This are a few features that can help you make a decision.

-Orlando






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