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Ranger Tim
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Reged: 03/25/08

Loc: SE Idaho, USA
Replace GM-8 Gemini I w/ Atlas?
      #5718743 - 03/07/13 04:16 PM Attachment (54 downloads)

I have had my GM-8 for a couple years and have never really gotten it dialed in so that PHD can use my SSAG to track well. Perhaps I am too picky, but my tracking always has some stupid fault that results in a high failure rate. I am shooting with a Canon on an AT6RC, 50mm guide finder (SSAG). I am not a beginner and am sure there are some issues with flexure that I need to address, but I have reached a point where the Losmandy is just not giving me the results I had anticipated. I do not have the money for a G-11 and would rather just sell to reinvest in an Atlas. I could then also pick up a NexSX board for my Sphinx. Any advice from the braintrust? It has gotten to the point where I haven't got the patience to get out there and image because of the frustration. Will I encounter the same amount of grief by switching mount platforms? I believe the Atlas will carry the load better and will give me a fresh start.

My GM-8 is in great shape and has a fine record of excellent go to accuracy with the Gemini, it just refuses to behave well when guiding with PHD. I don't intend to go back down the rabbit hole diagnosing the guiding issues but want to hear some push-back from Losmandy zealots and some urgings from Atlas enthusiasts. Here is an example of my last shot for a reference of what the GM-8 accomplishes. It is agony to get two full hours of data with no footballs.


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JoseBorrero
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Reged: 09/04/09

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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5718875 - 03/07/13 05:23 PM

I use a G11 and have a variety of scope including the AT6RC, I also lately have been guiding with a 50mm miniguide scope and the SSAG with very impressive RMS on PHD. I dont know if PHD settings can work similar on others mount scopes but If you like to try my numbers here they're:
RA agressiveness:97,
RA hysteresis:28,
MaxRA:391ms,
MaxDec:391,
MinMo:0.05,
Calibration step: 1000ms.

I went to a G11 because I knew I would try a variety of scopes, lately a C11, Meade 8 and ED80, I think is a good experience to be below the minimum overload range, would say by 40%, this mount 60lb payload if I have 35 lbs with C11 miniguide scope and camera,FW, that will be alright. Now, I have seen users using the AT6RC and the Atlas and the 50mm guiderscope, user like Rigel123, he's the best sample of the setup you trying to describe. And looks that work very well.


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: JoseBorrero]
      #5719253 - 03/07/13 08:12 PM

Tim, I think it's simply a case of your guide scope being too short.

I have been fighting declination guiding in my AP600 for years without much success (that's why I bit the bullet and got a Mach1) but what I noticed with the 600 is that my keeper rate was much higher when I used an OAG. Even when imaging at 720mm!

So if you could take a barlow to your 50mm guider.. try that and see..


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SMigol
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Reged: 07/30/10

Loc: California, USA
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5719695 - 03/08/13 12:11 AM

I used a GM8 for a long time, gradually peeling the layers of the onion with astrophotos. I really pushed that mount as far as I could. Got the Gemini 2 kit, One piece worm and block, HD tripod, and spent a lot of time tearing it down and cleaning it out.

Went with the G11 when I could get a good deal on a used one and migrated the G2 kit from the GM8 to the G11. Since you are already used to the Gemini 1, you could get a decent price on a G11 without goto and do the swap.

What drove me from one to the other was:
1. Weight. I was already at 18 lbs and knew that I was pushing the capabilities of the mount.
2. Flexure. While a lot of the problems with this issue were more with the rings and dovetails and camera sag and thus were not with the mount, I still feel that the burden of making things stiffer was better served by the G11.
3. Upgradeability. There are more aftermarket kits and parts and experience available with the G11 vs the GM8.

I still have my GM8. I've not decided if I want to keep it as a grab and go just yet or if I want to use it as a dedicated wide field platform.

I've learned a lot more with the G11 that the GM8 prepared me to understand. I think that when I go back to the GM8 to use as an additional platform, I'll be much more productive.

Regarding the Atlas, I've heard great things about them from people that use them. There's still gnashing of teeth - as far as I can see it's not much different than the Losmandy camp. There is a wealth of knowledge from people all over the place that have figured out their own setups.


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Startraffic
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5720441 - 03/08/13 12:34 PM

Tim,
I've never had a G8. I started with a used G11, DDS, PS & HD tripod. I added the encoders, OPW, & finally G2. I loved that mount but with a 10"f4SNT, 90mmf3 GS & cameras I felt it was pushing it's limits @ #40. I bought another Older HGM-200 with G1. It is what the G11 is to the G8 & still performs like a champ. I migrated the G1 from the HGM & the G2 to the HGM. Both are great mounts. I contacted Losmandy about the HGM & they still had parts. I needed a set of Bearings & Clutch pads & wanted a Polar scope. I got the bearings & pads but no Polar Scope was made for the HGM. The mount is pre-1995, & they still had parts in stock! That alone says a lot about the company that builds mounts as a side job.
You already have & know Gemini. I can tell you for a fact the parts will swap over & perfectly. You'll need to tell Gemini it's now on a G11 instead of a G8. The single biggest problem IMO with the G8,& G11 are the original worm blocks. Not a great design, too many points of possible misalignment. The MFWB, Ovision, & OPW are an answer. Proof of that is the new GM's come with them. The option is the worm itself, Steel or Brass upgrade for $65. No brainer Brass. I put one on the RA on the G11 & the mount was transformed. My BP dropped, & PEC went from the mid to upper 20's to lower 30's to 3-4". After running the PEC it came down even further to 0.5", completely acceptable (for me YMMV). If the worm starts to lag, Loosen one bolt, give the thumb screw a 1/8 turn, let the mount pick back up & tighten the bolt back up, done.
I've seen a number of G11's come up recently on CN & AM for >$1500 running the DDS. Add in a Brass OPW & you're still ahead of the cash flow.

Clear Dark Skies
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39.138274 -77.168898


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Startraffic]
      #5720607 - 03/08/13 01:56 PM

Quote:

The option is the worm itself, Steel or Brass upgrade for $65. No brainer Brass.




If you don't specify brass vs steel with the OPW, which do you get these days?

Gale


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frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: gdd]
      #5720885 - 03/08/13 05:33 PM

At this time I would no longer buy a new Orion Atlas EQ-G (aka Sky-Watcher EQ6 SynScan).

The new Orion Atlas Pro AZ/EQ-G (aka Sky-Watcher AZ-EQ6 GT SynScan) appears to fix just about everything that people have ever complained about with the older mount. I'd get that one instead.


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Startraffic
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: gdd]
      #5721034 - 03/08/13 06:57 PM

Gdd,
The G8;G11 options are "OPW without worm $295, with High precision worm $355" http://www.losmandy.com/access.html.
So, you can reuse your existing worm, steel or brass, or buy a new brass one. The price between the G8 & G11 is the same. I did notice that they don't sell the stainless worms anymore. The Titan already has the OPW but only stainless worms.

Clear Dark Skies
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andysea
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Reged: 09/03/10

Loc: Seattle, WA
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5721109 - 03/08/13 08:04 PM

Why don't you try to use an OAG before giving up on the mount?

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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: andysea]
      #5721161 - 03/08/13 08:44 PM

RT, I think it's tunable. Perhaps it requires a new worm (depends on the age), perhaps it just needs to be regreased. Have you tried the losmandy Yahoo! Group yet? I think they might be able to give you ideas on what you need to do. What is your periodic error right now? How do you balance? How's your declination balance with the 6RC?

The mount 'should' be perfect for the size scope you're using. I think we can probably figure it out for you .

But, an Atlas with a AT6RC would be good too. How much you want for your GM8?


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gdd
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Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5721167 - 03/08/13 08:46 PM

Quote:

I don't intend to go back down the rabbit hole diagnosing the guiding issues




But if you are having guiding issues that are not related to the mount, switching to an Atlas will not solve anything.

Gale


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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5721458 - 03/09/13 12:38 AM

Hi Tim,
I have owned Meade, Skywatcher, and Celestron mounts. I think my CGEM DX mount is the best mount I ever owned. It did great imaging right out of the box. I have been reading alot of good stuff about the new Atlas mounts. I almost bought one. But instead

Last December I bought a new G-11 Gemini 2. It had 28 arc sec. of PE. I got an OPW with brass worm and got 31 arc.sec. of PE. And thats after alot of tweaking. Guided it still had football stars. After some complaining Scott made me a new worm with 9 arc sec of PE. This worm is much smoother too but I still cannot get consistantly round stars.
I never had so much trouble trying to image with any of my other mounts.

Neilson


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5721564 - 03/09/13 03:19 AM



for every happy G11 story there is a Neilson story. Or maybe the happy folks never pipe up so we hear all the sad stories.

It is still disappointing for a $3600 mount, and a cautionary tale for anyone deciding to upgrade from an Atlas or EQ6. Or even CGEM - although the CGEM has the notorious 8/3 harmonic, the G11 has the equally notorious 31.7 second harmonic...

All the tales that I've read here seem to inevitably point to one conclusion: if you're at Atlas/CGEM level and want a significant improvement, the G11 ain't it. Not to say the Atlas/CGEM are superior - I think they're not, but they're also less than half the price.

I still do not think an Atlas/EQ6 is a meaningful improvement over a GM-8 - at best it would be equal, albeit with more payload - but you can meaningfully improve an Atlas by adding the Aeroquest worm, which is only $100.

If you really don't want the GM-8, I'd say go for the Atlas. If you get one with a huge PE, the $100 Aeroquest worm will immediately bring you down to 15" p-p or less. This is also assuming you can get decent $$$ for the GM-8. I would not buy the new AZ-EQ6 though; untested, not sure if you can get Aeroquest worms for it, etc. etc.


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RogerRZ
Whatta you lookin' at?
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Reged: 01/09/06

Loc: West Collette, NB, Canada
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5721658 - 03/09/13 05:37 AM

There seems to be a big hole between the CGEM/Atlas and the next meaningful performance step, isn't there? I've been tearing myself apart with this very question, and I think I'm near a conclusion. I hope it's the right one...

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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: RogerRZ]
      #5722063 - 03/09/13 11:10 AM

Roger,

I dunno, I picked up a used Mi-250 for just a tad more than a G-11 would've cost. I think the big thing is to aggressively test your rig with PEMPRO and be willing to send it back if it doesn't meet expectations. Most the stories I read about are,"I bought a new G11 and it isn't performing..." and the individual spends months troubleshooting it... if they'd sent it back and got a new one, maybe it was a bad batch? Instead they elect to fight through it, learn a bit about the mechanics of the mount, and end up getting a phenomenal mount.

I think a G11 is usable. Orly last time I checked you can get around the 31.7 by doubling your worm gear time in PEMPRO and the fixing a curve to it. Mind you, I don't have one, that's just what I've read.

My guess is there are lots of happy G11 owners out there. Otherwise Scott wouldn't be in business. We just tend to generalize quite a bit (CGEM/G11/only buy AP)


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Ranger Tim
scholastic sledgehammer
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Reged: 03/25/08

Loc: SE Idaho, USA
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: RogerRZ]
      #5722073 - 03/09/13 11:12 AM

Interesting comments. Thanks to all who took the time to respond. More folks from the Losmandy camp, but that was expected. And thanks for the numbers Jose, I'll give them a shot.

Yes, the grass is always greener on the other side. I constantly question myself whether I made the right move going to the GM-8 instead of the Atlas. It seems there are many examples of people getting great results with the Orion mount and I would like to move to an eight inch imaging reflector at some point. I also have some homemade glass that will end up around 20 lbs. net when finished that I would like to mount, and the GM-8 will be struggling to handle it.

I'm going to put the Losmandy on a post in the yard and try to resolve any flexure issues once more before I cash it in for another, heavier mount. I still have my Sphinx for portable visual set-ups and really love it except for the declination bounce. The temptation to upgrade to a G-11 is also present because the Gemini I will transfer easily.

I have torn my GM-8 apart multiple times and it is Superlubed and tuned to a high degree - I cannot see any improvement in the mechanicals unless I am overlooking something. When I received it second-hand it was in less than ideal shape (to be charitable) and I learned a great deal about how to field strip it and solve problems. The worms are still original - several were supplied, along with a one piece block that has bad bearings. All original worms are stainless and none causes any better P.E. than any other. I guess $60 is not much to lose in an attempt to try and better the P.E.

I think the main problem I have is the interface between the Gemini and PHD. It seems to bounce back and forth, involving worm backlash and I can't get a handle on it regardless of balance issues. Each time I set up it is a different animal so I am looking forward to a permanent pier in order to remove some variables. Are you tired of burning through 3 hours of dark time just to get in the ball park? ME TOO! "Can you say observatory? Sure, I knew you could."

If folks want to continue to respond I would love to read what they have to say, but I guess I was just lapsing into a pre-season venting before I get carried away with galaxy season efforts. This is my favorite time of the night sky calendar. I think I would still like to hear more from Atlas owners about whether they are really happy or whether they are enviously looking across the fence from the other side. Perhaps the key may be found in a G-11 upgrade. I have friends that tried it and are still happy they made the switch. My mileage may vary! There is no point in trying to upsell me into a more expensive mount (>$1500) because that is totally out of my budget. Please look at my signature line...

I don't get to look at this forum much, so sorry for the lag in response time, but I'll be back. Thanks again!

Edited by Ranger Tim (03/09/13 11:18 AM)


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Raginar
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Reged: 10/19/10

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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5722103 - 03/09/13 11:26 AM

RT, going permanent will make you very happy. Skipping setup/tear down really made the difference for me. I found I didn't mind doing alignments... but being able to skip polar aligning AND setup/tear down??? Totally worth it.


Good luck!


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Raginar]
      #5722107 - 03/09/13 11:30 AM

Also... a really good polar alignment will make guiding much less hassle - you can use longer guide exposures (which smooth out atmospheric seeing and rapid gear noise) and there will be less corrections necessary.

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Startraffic
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5731871 - 03/14/13 09:45 AM

Orlando,
You're right. It's very confusing & frustrating for the ones who get the "Monday morning" mounts. I've heard on the Yahoo site that they got a batch of bad worms last summer & those were installed & shipped. I think Hilmi over in Oman got one of those which caused him a ton of problems. Scott did send him a new set, but it took several months of troubleshooting on Hilmi's part to figure it out. Shipping it back was simply not an option for him. I got lucky when I upgraded to the OPW. My brass worms were awesome right out of the bubble wrap. I put one in the original worm block setup & worked my way through that refit. A 4" 'C' clamp became my best friend. I think Neilson may have also been a part of that batch which may explain some of his problems. I'm not sure who is doing the QC at HGM, but the G11's seem to be having problems that the new G8's & Titan's aren't having.
I can say that of the 6 mounts I've had a DS114, ETX90, Vixen GP, LXD-55, G11, & the HGM-200. The G11 & 200 have given me the least problems, but none of them have been trouble free. Most of the problems I had were due to poor maintenance. The G11 had a broken gearbox & hadn't been lubed so it was having serious motor lag issues. The HGM had a frozen bearing, & the other 3 were so gummed up I just replaced them. All of which Scott had in stock.

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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Startraffic]
      #5732921 - 03/14/13 08:23 PM

Hi,
My third worm installed in my mount got 9 arc sec total PE. I polished it and now I consistantly get 3 arc. sec. total PE. I think my G-11 mount is terrific now. But my Gemini 2 is not. I had been testing my mounts goto's using alignment stars, they are good. But now after about 24 stars in the East/West models and a drift alignment I find that unless the DSO is close to an alignment star it will be close to the edge of my T1i's big imaging chip or hanging off the edge of it. I'm using a 9.25 Edge ota. I have been testing this for several days now. I have redone models several times each night and tried many different DSO's but if they arn't really close to an alignment star they are never close to the middle of my chip. Aparently even after a good east west model you must sync to a star near each DSO you want to image if you want it near the center. They wont improve the goto's to modern mount standards.

I have also found that the PEC is erased each time you turn the mount off. And you must retrain it.
I use the ethernet and PHd guiding and 3 out of every 5 days I get a lock up and have to restart my computer. 2 out of 5 days the mount locks up and I have to restart it. I was expecting these issues to be over after the last update, but they were not. The only thing I noticed was the stop sign and the removal of the IC and NGC catalogues. A substitute NGC catalogue was added but now were told getting an IC catalogue is not looking good.

At the $3,200 price point. I expected better. My Meade mounts goto's are centered or close to centered . My Celestron gets perfectly centered goto's. I'm told if I want goto's on my Gemini 2 to be centered or close to it I have to use my computer and other software or switch to a 400mm ota. No thanks.

This is not acceptable to me, I will probably be getting rid of this mount. I gave it every chance and fixed some of the problems but goto's are too important. I didn't want to, but I'm not going to spend half of each night modeling, then looking at a star map to find stars names that are real close to each DSO I want to image that night so I can make models around them.
I am willing to go through the overly long initial modeling(alignment) but I expect it to be accurate. Not to have to do additional modeling for each DSO goto.

neilson


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5733028 - 03/14/13 09:27 PM

Quote:

My third worm installed in my mount got 9 arc sec total PE. I polished it and now I consistantly get 3 arc. sec. total PE.




I Neilson,

Going from 9 to 3 arcsec error by polishing the worm is quite an improvement! What did you use and how?


Thanks,
Gale


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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: gdd]
      #5733200 - 03/14/13 10:58 PM

Hi Gale,
I was impressed by the results myself. I have a bench grinder and I install a buffing wheel made for bench grinders. I have a polishing compound thats a solid stick form. I press the compound into the wheel every so often and it grinds some off. into the cloth wheel. Then I very carefully press the worm into the wheel. I hold both ends. It will try to fly out of your hands. If it does it could damage the worm. I slowly turn the worm. It must get warm to polish the metal and smooth it. I only press it in about 15 to 25 seconds at a time. You will notice it get smooth and shiney quickly. after about 2 to 5 minutes its done. You have to clean the excess compound off the worm. You only have to polish the middle since thats the only place the gear contacts the worm. I don't advise doing this because it's easy for the wheel to pull the worm out of your hands and send it flying. You can also get seriouse injuries. I have read of others using one of those dremel tools with a little buffing wheel and polishing compound. It would be safer. I already had the bench grinder and wheel for 20 years so I dont know where to get one now.

I install my worm with very little backlash. My power supply has an amp meter and when I slew it draws about 0.40 amps, or less than half an amp. Then I slew from one end to the other in RA about a dozen times, pausing after each slew for 20 seconds although the motor stays cool. When I was done it was only drawing 0.29 amps when I slew. I feel only a tiny bit of backlash when I wiggle the counterweight bar. Almost none.

neilson


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5733317 - 03/15/13 12:17 AM

If such improvements are doable with a bench grinder and polishing wheel,

1) why doesn't Losmandy do this (they could charge more for it)

2) why doesn't Ed Thomas do this?


Neilson, regarding the GoTo accuracy -

I think I am having better GoTo accuracy with my Mach1, but it's still not perfect, because with these 1-star-align mounts, GoTo accuracy is determined by both how good your polar alignment is, and how orthogonal your OTA is to the mount.

Even if your PA is perfect, if your OTA is not perfectly orthogonal, you'll still have some pointing errors. Situation is the same - need to sync on a bright star near the DSO (near meaning within about 10-20 degrees) to get a good GoTo.

In my opinion the most accurate GoTo's are had with the Celestron Nexstar.

I actually had this idea... if you could combine a Nexstar with an AP mount, you'd have a mind-boggling combination. The AP mounts all have their motors separate and external, with a normal mil-spec connector. So if somebody built a motor board that is compatible with Nexstar but set up for the gear ratios of the AP.... then this would be possible.

I know that the NexSXD folks already have done this for the Vixen mounts.


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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5733445 - 03/15/13 03:08 AM

Hi'
I do a drift Polar alignment. I have checked the ota's orthoganal several times. My goto's to the alignment stars are dead center now just not to DSO's, unless they are pretty close to an alignment star. After 24 stars in a model you would think everything would be dead on. But with Gemini 2 you are expected to build additional modeling where you plan to image. The Gemini 2 alone costs $1,600. That's more than most mounts cost.

I am still having lock ups in PHd from the ethernet bugs that require me to restart my computer and handbox lockups that require me to restart my mount and start over.

After most of my DSO goto's are on the edge of my imaging chip again tonight. And two were completely off the chip. Jupiter, and a nebula were centered. The handbox locked up. PHd locked up and several times I had runaway in RA. All this tonight. And most nights.

Because of all of this I will be getting rid of my new G-11 Gemini 2 tomorrow. Mostly because of the requirement for extensive alignment modeling that give poor goto's at best. Everything should get fixed eventually with future firmware updates but they are not going to fix the poor goto problem. I will be buying another new CGEM DX with its very accurate goto's. And an aeroquest worm probably.

I don't know why polishing my worm lowered my goto's but I have tested it a dozen times over several days. Maybe I just got lucky. Polishing the worm this way is difficult and dangerouse if it gets away from you. With PEC I get 1.7 but it must be retrained each time the mount is turned on. I was really happy I got the PE so low but it makes letting the mount go very hard.

neilson


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5733453 - 03/15/13 03:46 AM

PEC training disappears every time you power off?

what kind of thing is that Gemini 2?!?!?! that sort of non-permanent PEC is what you expect from early 1990s Celestrons or the CG-5. Not a pricey piece of electronics like the Gemini 2.

Having a CGEM, I would respectfully suggest that you don't downgrade to one from a G11... maybe try to get the Gemini 2 unit changed. or buy a Gemini 1.... PEC works on those things


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neilson
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5733893 - 03/15/13 11:04 AM

Hi,
I already had the Gemini 2 unit changed a few weeks ago, along with the handbox. It did fix some other problems but not these. The PEC erasing is being reported by others too. You hit it on the nose, It does feel like I'm using a system from 1990. Little things like the screen where it tells you how far you are from the pole isn't in arc minutes and arc sec. its just in arc seconds. you get numbers like 14250. or 2795. If your 5 arc minutes off it reads 300 Meaning 300arc sec.

My CGEM DX was the best mount I ever owned but the electronics died a few weeks after I got it. Celestron sent me a replacement that didnt even turn on, then one with a 45 arc sec spike every second turn of the worm then one with high PE. All 3 replacement mounts were ones that had been returned defective by someone else. They were on backorder after a big sale, and instead of telling me that, they sent me used defective mounts. I can't afford an Astro Physics mount. Theres just nothing else inbetween the CGEM DX and AP mounts that I know of.

neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5733922 - 03/15/13 11:19 AM

Used Tak NJP? A couple sold for $4000 a few months back. You'll have to wait a while for one to pop up though. If you don't need the 70lb payload used Tak EM200's are also out there for less (but the NJP is the best "payload for the buck" used premium mount out there).

It has a primitive handset, no GoTo unless you have a PC attached, one-star align only, but the periodic error is fantastic (2.8" p-p). No PEC but with periodic error that low.. I was aiming to get one, but the CFO disallowed it on ground the NJP is a really old design - it dates to the late 1970s.

Rob Vanderbei has some really good work with the NJP
http://www.princeton.edu/~rvdb/images/NJP/ngc7635.html


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gdd
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5734006 - 03/15/13 12:12 PM

Gemini-2 permanent PEC works for some, must be a recently introduced bug. Neilson is already getting low PE, so I don't think the NJP would solve the problem, it is accurate reliable GOTO's that are wanted. I think he really needs both which is why I don't think we will be satisfied with an upgraded CGEM DX which has a high 8/3 gearbox error that defeats the PEC.

However, getting back to the original question, since the OP is happy with the GM-8, he should be happy with the GOTO performance of the G11/Gemini.

Gale

Edited by gdd (03/15/13 12:18 PM)


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neilson
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5734067 - 03/15/13 12:44 PM

I really want goto's on the handset. If I was willing to use the computer I could just keep the G11 and use other software for my alignments. And I couldn't spend that much for something used. But thanks for the suggestion. I wish there was something else in the G11 price range or less.

Gale,

I'm not the only one reporting the PEC bug. I have been testing it many times each night and every time its erased.

neilson

Edited by neilson (03/15/13 12:57 PM)


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5734094 - 03/15/13 12:56 PM

Quote:

I really want goto's on the handset. If I was willing to use the computer I could just keep the G11 and use other software for my alignments. And I couldn't spend that much for something used. But thanks for the suggestion. I wish there was something else in the G11 price range or less.

neilson




The new goto handbox for the Tak Temma units will be released (finally!) next montn at NEAF. A good used EM-200 plus a new handbox might run you $4000 or so; not much more than a new G-11/Gemini. A more economical alternative to a G-11 is a CGE. Those are available only used but at least that way they are less expensive. Permanent PEC (with real worm index switches), orthogonality compensation in the controller, ASPA, ...


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: jrcrilly]
      #5734306 - 03/15/13 03:11 PM

... and homing switches!!!

Yes, a CGE is a good alternative at $2000. You'll even have some money left over after selling the G11 for the Bennett mod.

and if the periodic error on the CGE is not to your liking, Aeroquest sells a replacement ring gear for $250. Not sure why Jim doesn't sell a worm though..

Overall a superior choice to the CGEM DX.

John - I bet that new Tak handset will be $1000. The old one was..

So $6000-odd for an EM200, another $1000 for the handset. No thanks, I'd rather have a Mach1..!


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5734392 - 03/15/13 03:52 PM

Yes the cge would be a great choice but even at $2,000 Its hard for me to buy a used mount site unseen. My luck it would be trashed out. And I dont believe in that saying "all those scratches and dents dont effect seeing." I got cheated once already buying a used mount/scope setup on line a few years back. I will call the telescope stores, they might have a used one.
Thanks for the suggestions

neilson


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5734400 - 03/15/13 03:56 PM

Odd, I've had almost zero bad experiences buying used stuff sight unseen. I've been 12 years on a-mart and longer than that on ebay...

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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Ranger Tim]
      #5734469 - 03/15/13 04:45 PM

You can probably get a used G11 Gemini I for about the same as you'd pay for a new Atlas. I dumped my GM-8 (non Gemini) for an Atlas and could't be happier for visual use. Flexure problems with the GM8 start with the flimsy stock tripod. You might fix that by moving the head to a G-11 tripod (lost get sold used when folks move their G-11 head to a permanent pier) or to an A-P pier.

But if you're sure that you don't like Gemini for imaging, the Atlas wouldn't be a terrible option. Avoid the Sphinx, though. On the value front it Stinx.

Have you considered a used Takahashi EM-200? You could probably get one of those used for what you'd pay for a new Sphinx plus the Nexstar mods, and it'd be a heck of a lot more precise mount. You can even drive the EM-200 with Sky Safari and a smart phone/iPad.

Regards,

Jim


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: jrbarnett]
      #5736000 - 03/16/13 11:12 AM

I think none of your options will fix his complaints minus PEC (not if he buys a TAK obviously). He wants accurate GOTOs, and my Nexstar still required me to use "precise GOTO" or syncing to get the object exactly where you want it for AP. I think what he's looking for isn't really possible with any of the mounts except maybe through Starlock/Sky Prodigy. CGEs have mechanical issues and, from what I've read, the large electronics pier is frustrating. As Orly pointed out, the 1-star with a AP mount isn't great. Personal experience tells me a CGEM will not meet your expectations either without a precise GOTO (or platesolving).

Neilson, what about just running a laptop and using Astrotortilla or Pinpoint? You'll find it to be much less painful.

Chris


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: Raginar]
      #5736136 - 03/16/13 12:08 PM

If you are looking for a low-tech solution, how about using your finder or guide scope to take a wide field image to detect the DSO and then get it centered and framed. The star patterns you see on the wide field image can be used to help you fine tune the framing on the narrow field shot.

Gale


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neilson
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: gdd]
      #5736450 - 03/16/13 02:44 PM

Hi
I owned 3 CGEM DX's with their newest firmware for a few weeks each and it hit everything centered every time on all three.
I dont want to use a computer all the time. I am very careful with balance and leveling and checking and adjusting ota perpendicularity. I use an illuminated reticule and center every star perfectly.

I no longer own my G11 Gemini 2. It was very hard to let it go but after emails with Rene I felt it was best. I will have to build lots of models for the DSO's or buy Tpoint or the Sky. Or Astrotortilla.
I think that mount is best mounted permanently so you can build all the models one time and be set. Building all those models every night is time consuming and I don't know the names of the stars next to most DSO's to add to the models.

I'm thinking the DX then that new device that does the alignments automatically. I think its going to be released. They claim it will make your goto's even more accurate. The tripod is rock solid on the DX. I already have experience doing the hypertune myself. After the Hypertune I had about 7 arc sec total PE and with PEC it was under 2 arc sec. And I only had to record the PEC one time and it stayed in the mount after I turned power off. I am not in a rush so I will still consider other options. In my opinion the regular CGEM is not the same. The tripod, larger weight bar, and improved power chip makes a difference on the DX.

I think the Atlas would probably be better than the DX if it came with a heavier tripod.
Thanks for the suggestions, I'm still deciding.

neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5736559 - 03/16/13 03:58 PM

am surprised you could get 2" after PEC... on most of these CGEMs the 8/3 ranges from 6" to 20" plus...

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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5736622 - 03/16/13 04:42 PM

Orly, I agree. That's phenomenal with a CGEM! I'd love to see the graphs. It might convince more people to go that route if the data was available. I liked my CGEM; I just didn't like it's internals for the weights I was using it at.

Neilson, you thought about an MI250 with a Gemini2? Native PE of around 5" and it has a conservative weight limit around 90#.


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5736635 - 03/16/13 04:50 PM

Hi,
I didn't have any of the 8/3 problems on my first mount. That I know of. On the second one I had a 45 arc second spike about every 2nd or 3rd turn of the worm. I'm not sure which. I thought it was the 8/3 but Celestron kept denying that it even exists. Then I showed them the statement in the Beta testers group at the time and they claimed that 8/3 was in Dec only. That mount went back that day. Do you think that was the 8/3.

I also read they were supposed to have a fix for the 8/3 around the first of the year. I wonder if the new mounts have that fix. I guess I better find out before I buy one. Or save up for the CGE Pro. I think I'm still in the Team Celestron Beta testers group, I will see if it's mentioned.

As of Feb 22 Derek started working on it again if I read correctly. In my opinion they might be planning to put the motors from the advanced VX in the CGEM and DX mounts. Saving for the CGE PRO is looking better but the sale will be over soon and it will take me longer to save enough.

neilson

Edited by neilson (03/16/13 05:27 PM)


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5736707 - 03/16/13 05:33 PM

if you are using pempro to read your PE, it throws away non integer harmonics, hence the 8/3 doesn't show up.

pecprep does show the harmonic, its the 181-second term.


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neilson
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5736822 - 03/16/13 06:21 PM

Hi,
I was using Pempro at that time. No wonder I never saw it. After trial period ran out and I switched to PecPrep. I just looked and it did have the 8/3 but it was not very high. It was about the same level as all the other spikes. I guess I was lucky. I am concerned about it now.

neilson


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gdd
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5737276 - 03/16/13 09:05 PM

Celestron's new AVX mount has integral gear ratios to make PEC more effective. I would think they would use AVX technology on a CGEM sized mount at some point, hopefully soon.

Gale


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: gdd]
      #5737880 - 03/17/13 01:26 AM

yup.. hence the theory "CGEM AVX"

I still have my CGEM, and maybe at some point Celestron will offer the AVX motors as a retrofit. It might be in the $400 range for both motors (and probably the motor board). So yet another case of throwing good money in after bad...

Neilson, Derick has stated that the 8/3 is generally around 6". So that's 6" that will never go away. But on mine, the 8/3 is 22" !!!!!! so even after putting in an Aeroquest worm, I could not get the PE (after PEC) below about 25".

I used the CGEM last night, and I realized that in spite of the good software it has (in addition to the irredeemable 8/3) a few other really annoying flaws:

1) the thumbscrew on the counterweight hurts your fingers, and you have to torque it down really tight because the rubber tip gives

2) the C/W shaft is non-beefy and cheesy

3) there is play in both RA and DEC even when everything is tightened down

4) the adjustment screws are rough in pitch, and there's a lot of friction/stiction when adjusting the azimuth

5) (worst of all) it is very heavy. Really bad weight-to-payload ratio.

That said... I would recommend purchasing pempro. The polar alignment routine is golden. better than ASPA! I easyly got within 2 arc-minutes of the pole with two of my mounts last night. About 15-20 minutes per mount.


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neilson
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5738040 - 03/17/13 05:37 AM

Hi,
Wow, thats really bad 8/3. Can the 8/3 be guided out with PHD guiding. If not how can anybody possible image with it. Or is it only bad in some older models.

I have read Derek say, and he told me himself, that he thinks only a very small percentage (less than 10%) of people image at all. I dont know where he gets that, if its based on sales of their imagers or not. But I feel most imagers use Canon Dslr cameras or SBIG or other high end cameras. Then he said that he thinks only a small percentage of those few do long exposure and a small percentage of them use long fl. Therefore fixing the 8/3 is of little importance.
I dont know if he tells Celestron this or they tell him. But I find that to be a poor attitude for a telescope company to have. And its a poor excuse to not fix it.

I can't believe that most poeple buy expensive ota's and CGEM mounts just to look at Planets and M42 and a few bright galaxies. No offence meant to visual observers.
I live out in the country with fairly dark skies but I expect that most use their equiptment in light polluted cities and can't see much at all and after a while move up to imaging.
Celestron upgraded the CG5 to the Advanced VX with new non 8/3 motors so I would think that it was so people could image with it better.

All this is making me wish the Atlas had a CGEM DX/Cge Pro mount. Or that the CGE Pro was more affordable. This decision is getting harder to make. I'm worrying, will I get another good CGEM DX like I did the first time before or will I get a bad one like the replacement ones they sent me after that.
I need another option.

neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5738065 - 03/17/13 06:23 AM

Neilson, the bottom line is, with an 8/3 as big as mine, guiding is mandatory. The 8/3 has a roughly 182-second period, so it can be guided out.

Derick's assumptions about how many are affected by the 8/3 is just that - assumptions. But the fact that Celestron changed to an all integer gearbox in the AVX, means that they acknowledge this issue.

The thing is, the lower the PE, the less you need to guide. I've heard tales of guiding corrections every 30 seconds, and I now believe that... After last night's pempro drift alignment, I got a 10-minute unguided sub at 600mm with round stars. Of course this was on my 0.5" PE (after PEC) AP.

But really if PEC worked well on a hypothetical CGEM AVX, I expect residual PE below 5". Which would be pretty good...


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5738110 - 03/17/13 07:25 AM

I'm glad it can be guided out but I'm like you I want low PE so guiding isn't needed. But I am realizing thats not possible with my budget. I still want low PE so my guiding will be smoother.
With that first CGEM DX I had I got 12+ minutes guided and 5 minutes unguided and 8 minutes unguided with PEC on if I remember correctly. The unguided weren't perfectly round stars or consitant but I was happy with the tests. I knew I could image for 2 or 3 minutes with PEC on when I didn't feel like setting up the computer. The huge tripod and thicker weight bar helped alot, especially on windy days.

I wish I could get an AP mount but ever since I became disabled and can't work on aircraft avionics anymore my income wont allow it. And I havent seen used ones very cheap. Or I would get one.

neilson


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5738124 - 03/17/13 07:57 AM

To my knowledge, the only mounts that cost less than AP's and can hit AP performance are... G11's with the Ovision worm. Your issues with the Gemini 2 are terrible to hear about, but I've a few friends with the Gemini 2 and their experience is nowhere as bad as yours. Still for $1600 you certainly expect and deserve better.

If you can tolerate having no mount for a few months, I'd wait for a "CGEM AVX." That way you don't spend twice. The CGEM DX has the same 8/3. The CGE does not, but then it'd be used.


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5738276 - 03/17/13 09:44 AM

Yes waiting for an AVX version would be ideal but I might end up waiting for something not coming anytime soon. And miss the sale going on now. It would be nice to have some inside information about now.

Hay Celestron send me an email and let me know. I'll keep the secret. They probably think I would buy both, they are mistaken. The value of the old one would drop too much for me to sell.

I've never seen a used CGE Pro but If it looked nice I might buy one.

neilson

neilson


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5738357 - 03/17/13 10:36 AM

I just located a used CGE for $1775.. I'm not familiar with their problems though

neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5738505 - 03/17/13 12:23 PM

Cable problems. For that price it probably doesn't have the Bennett mod. That's a pretty good price actually.. IMHO a better choice than a CGEM DX, since at least the CGE is Made in USA and has Pittman motors (with no dreaded 8/3). I am not sure about the spares situation though.

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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5738624 - 03/17/13 01:32 PM

Hi'
It has upgraded RA/DEC cables from scope and stuff and ADM knobs. He claims to have been used fewer than 20 times and is in excellent cosmetic and operational condition. The pictures look great. also with original boxes.

neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5738688 - 03/17/13 02:07 PM

Between this and a CGEM, I'd probably go for this.

No warranty, but then no 8/3 either. Pretty much same price.

Looks like Celestron still stocks parts -
http://www.celestron.com/astronomy/parts/cge-mount.html

I can't see the prices, as I'm not in the US. So the situation with the CGE is exactly the same as with any other used Celestron mount.

Look at the picture of the motor - it's a Pittman

not a cheap made in India Igarashi.


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5738764 - 03/17/13 02:41 PM

Hi,
The motor board is $237 and the motor is $383. lots of mark up there but at least their available. I really like that about Celestron, you can buy parts. But if you touch anything, even the backlash adjustment when its under warranty they threaten to void the warranty.

neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5738774 - 03/17/13 02:44 PM

If you price the Pittmans separately they are still north of $200. A far cry from the $20-odd motors in the CGEM and CGEM DX (and CG-5).

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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5738957 - 03/17/13 03:48 PM

I contacted the seller and its a 2006 model. I was about to buy it at the $1775 price but someone else is trying to buy it now and I'm not going to play bidding games. There will be others.

neilson


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5739891 - 03/18/13 12:15 AM

Hi,
I ended up buying the CGE for $1625. I am sure I will be happy with it.
neilson


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orlyandico
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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5739919 - 03/18/13 12:37 AM



Much better choice than a CGEM DX, congratulations!

Probably a good idea to go for the Bennett mod though.. and with the money saved you'll have some funds for parts if ever.


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5740481 - 03/18/13 11:12 AM

Quote:

Hi,
I ended up buying the CGE for $1625. I am sure I will be happy with it.
neilson




Neilson,

To be honest, based on the problems that you have had, I'm sure that you will not be happy with the CGE. While it is a good mount, it has many of its own problems including a dead zone in the DEC axis that can be very problematic for calibration purposes. As with many things, this problem varies, but with the demands that you tend to place on mounts, I expect this to be a problem for you. The CGE is no better than a G11 and can easily be worse. If you don't end up happy with the CGE, you really need to save and move up to something like an AP after this. I think that you are wasting a lot of time and money on lower end mounts looking for higher end performance.


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Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5740505 - 03/18/13 11:22 AM

Quote:

... and homing switches!!!

Yes, a CGE is a good alternative at $2000. You'll even have some money left over after selling the G11 for the Bennett mod.

and if the periodic error on the CGE is not to your liking, Aeroquest sells a replacement ring gear for $250. Not sure why Jim doesn't sell a worm though..

Overall a superior choice to the CGEM DX.

John - I bet that new Tak handset will be $1000. The old one was..

So $6000-odd for an EM200, another $1000 for the handset. No thanks, I'd rather have a Mach1..!




I miss the homing swithes - great feature! The Tak handbox will surely be $1000 but with good used EM-200s going for not much over $3000 you'd be at $4000, which sounds like a great value to me.


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jrcrillyAdministrator
Refractor wienie no more
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Reged: 04/30/03

Loc: NE Ohio
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5740529 - 03/18/13 11:34 AM

Quote:



Much better choice than a CGEM DX, congratulations!




Yup. A buddy of mine has both, and sets them up side by side. The CGEM-DX can't compete. I've not owned a CGEM of any flavor, but I've owned a few Atlases and they were no competition for my CGEs.


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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: jrcrilly]
      #5740738 - 03/18/13 01:38 PM

Hi,
I would buy an AP right off but Its way above what I can come up with.

I really like the Celestron firmware and I think If I got a good CGEM DX like I had the first time I would be happy. So if the CGE is better I will be happier. I don't mind if I have to do some hypertuning to it. I have taken apart every mount I have ever owned and done some tuning and improved the performance.

The G-11 made me lower my expectations on unguided imaging. I finally got low PE but PEC needed to be turned on to stop the RA drift. And since I had to go to the trouble to hook up my computer each time and retrain the PEC and check it, I might as well do guided imaging instead.

If I can get the PE low enough I will be able to do unguided imaging with the CGE but I'm not expecting it to get that low. But I will try to get it lower just for good guided imaging.

I don't understand what a dead zone in the CGE's DEC means. I can't find any information on line about it so far except one thread about balance in the DEC. on the CGE yahoo group.
I couldn't imagine any mount to be more criticle with balance than that G11 I had.

I expect the CGE will have great goto's like all the CGEM DX mounts I had did as long as I use the most recent updated firmware. I have lowered my expectations on PE and realize that I dont have enough money to afford unguided imaging but I'll probably get an aeroquest worm gear to see if its possible.

I did consider a TAK but I couldn't find any used anywhere near what I could afford and this CGE popped up first.

I have been reading every review I can find on the CGE and I think I will be happy with it.

neilson


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5740782 - 03/18/13 01:58 PM

Quote:

I don't understand what a dead zone in the CGE's DEC means. I can't find any information on line about it so far except one thread about balance in the DEC. on the CGE yahoo group.




The "dead zone" (I'm really not sure what else to call it) is something that I have run into recently but have now talked to or heard of a number of people with the problem including the two CGEs that I have. I have seen it in both untuned and tuned mounts. I am sure that it varies with each mount, but I suspect that it is systemic in the CGE mount overall.

Essentially what happens is that in a large zone of the sky corresponding to your latitude (+/- up to 30-40 degrees), when the DEC is in a position that it is symetically balanced there is a problem where, when you change directions, the axis makes a quick jump forward and then stops and then starts moving in the choosen direction at the choosen rate. At high speeds it is not visible but at speeds below 5 it becomes very obvious. As far as I have been able to determine it is related to backlash between the worm and the worm wheel. Off-balancing solves the problem, but since the problem is in DEC, a dynamic off-balancing system would be necessary to always take care of it and that gets even more difficult if the problem occurs over a large swath of the sky. It is likely a combination of a mechanical issue and an electronic issue where the mount starts moving with a small power surge (similar to anti-backlash) in order to overcome any stiction between the gears.

Ideally, reducing the backlash would help, but CGE worm wheels are rarely round (like many gears) so that it is not possible to reduce the backlash sufficiently to take care of it. In addition, if the gears are too tight that leads to other problems. My thinking at this point is that a spring loading system for the worm is the only solution. This also explains to me why Celestron went with a spring-loaded worm in the DEC axis only when the CGE Pro mount came out. While spring loading can be accomplished, it is not easy and the only solution I have right now is fairly inelegant.


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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: EFT]
      #5740841 - 03/18/13 02:41 PM Attachment (12 downloads)

Hi ED,
Thats very interesting. And I think your reasoning of why the DEC only on the Pro is spring loaded is valid. I will have to look out for that. Thank you.

My 9.25 Edge is balanced in every direction. I have a laser and 9v battery powered brightness controller for my illuminated reticule on the opposite side of my finderscope for balance. On the front I have a small one pound weight. The hole in the weight is off centered to one edge. A small rod pointing down holds it. I can adjust the tightness so I can tilt it to one side or the other to create a slight off balance if needed. It can also be loose and would switch sides when going over the meridian. Maybe something like this would work. It could be made different ways but the weight comes off my LX200R 10" ota"s sliding weight set. Here is a pic below

neilson


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5740866 - 03/18/13 02:52 PM

I don't think that dead zone will be a huge issue. You would only be imaging 1-2 objects per night anyway. So point to your object, then move the weight to ensure that the DEC is heavy on one side...

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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5753103 - 03/24/13 01:22 AM Attachment (7 downloads)

Hi Everyone,
I got my almost used CGE mount today. I opened the boxes. It looks brand new. No Scratches or scuffs or faded paint. Its been packed in the box for years after only a few uses. This mount is heavy duty, solid. No cheap plastic here. No corners cut when they built this mount.

Theres no stiction. I love the way it finds the home spot all buy itself on startup. I did a 2+4 alignment then did a goto to a DSO and it was dead center in my 12mm reticule eyepiece using my Edge 9.25 ota. with Orion 80mm guidescope, 2" flip mirror, Canon T1i camera and Dsi IIc. All about 34lbs load. I had updated the firmware to the most recent version.

Then I wanted to try an initial PE run to see just how bad this mount was. It was just over 3 arc seconds total PE.
I am very happy about these first results. I will do more tests but they should all be good after this. This mount is very quiet. When it slews on high speed it just makes a little humming noise.

I want to thank all of you who gave me this great advice. I couldn't have done better. I was afraid to buy something used but I was wrong. Now I have a mount that performs great and is practically brand new for only $1,629.
I know it's still too soon to be 100% sure but I think this mount is the one. I have not done any imaging yet but will soon. This is the best mount I have ever owned, and I didn't have to do anything to it.

neilson


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orlyandico
Postmaster
*****

Reged: 08/10/09

Loc: Singapore
Re: Replace GM-8 Gemini I w/ Atlas? new [Re: neilson]
      #5753252 - 03/24/13 04:28 AM

Congratulations!

Souns like you must have gotten a very good one if is it 3" p-p PE out of the box.. Celestron only warrants +/- 5" for the CGE Pro (and 3" p-p with PPEC enabled). The old CGE had no periodic error guarantee at all..


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neilson
professor emeritus


Reged: 08/22/10

Re: Replace GM-8 Gemini I w/ Atlas? new [Re: orlyandico]
      #5753514 - 03/24/13 10:00 AM

Hi,
I was amazed my PE was so low. I havent tried the PEC yet but will soon. I wont have to do weeks of testing and adjustments on this mount. I will finally get to go back to imaging. This time long exposures will be easy and with round stars. Now I will be able to take my imaging to the next level. I am very pleased.

I just noticed theres a CGE on cloudy nights classified that looks nice and clean and even has the orange knobs. The price looks good too.

neilson

Edited by neilson (03/24/13 06:16 PM)


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