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Sphinx vs. CGEM vs. GM-8 vs. ??? for TV-85 AP

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#1 Renae Gage

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Posted 11 July 2009 - 11:25 AM

I am finally going to make the leap into DSLR astrophotography. I am currently working on mastering my camera on terrestrial subjects, but am getting close to the point of buying my GEM for night-time work. I'd like your opinions on these mounts, and anything else I might be missing. Here are some of my experiences/values/preferences to let you know where I am coming from:

1. I have owned GEM's in the past, specifically an Atlas, a Tak EM-10 and a Losmandy GM-8. I eventually found that for visual use, all were more trouble than they were worth. Obviously in AP, I need a GEM, but the more simple/elegant the better.
2. I am an unrepentant Apple user. Any system that requires Windows for operation, updates, etc. goes WAY down my list.
3. The lighter the better. I am not particularly strong. I will be setting up from scratch every night (even though my home skies are fairly dark) and I've recently destroyed my left shoulder.
4. So far in my research, I like the sexiness of the Sphinx and the precision (machined vs. forged) of the Losmandy. The ability to do precise polar alignments very quickly seems to be a strength of the CGEM.
5. Quiet is better than noisy, but for aesthetic reasons--I have no close neighbors to wake up, and the cows like the company.
6. My scope is a TV-85 and my camera is a Canon 500D (T1-i), unmodded at this point. I'll mod later when I've gotten the hang of focusing and image acquisition. Baby steps...
7. I'll need a lightweight AG set up as well, and it must be OS X friendly.
8. I have some money, but the sky is not the limit. I'm sure your Mach 1 is nice, but I'm not going to spend more than $2500, and I'd like to spend considerably less.

Your thoughts and experience would be greatly appreciated. I think I'll be moving into widefield images by September at the latest.

#2 Luigi

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Posted 11 July 2009 - 11:39 AM

Hmmm, you find a GEM more trouble than it's worth AND you're an Apple user. This does not bode well...but let's give it shot anyway. :grin:

IMO, and believe it or not, I think you'd find a CG5ASGT to be just the ticket. It works very well and with auto-guiding would be an fine imaging platform for an 80mm refractor. The new polar alignment routine makes achieving good alignment easy and straight forward. No computer, either PC or Mac, is needed. Many get great AP results with it using much larger OTAs up to 20+ lbs.

Going bigger, the CGEM would be a logical step. It has the same polar alignment software.

#3 GaryML

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Posted 11 July 2009 - 05:50 PM

I don't do AP so I can't comment on the comparative performance of the mounts.

As an Mac user, I can tell you that NONE of the mount manufacturers support Mac for firmware updates. To update a Synta mount (CGEM or Atlas) you not only need Windows but you need a serial port (which no Mac has ever had). You can get USB to serial port adapters but they require drivers (Windows only of course) and can be unreliable. In this regard, the Vixen is the best as it skips the serial port connector and uses a standard Ethernet connector for updates -- you just plug it in to your router and it gets its IP address using DHCP. Very cool. But the firmware updater is Windows only. You can try using Windows in an emulator (Parallels or VMWare), but that introduces an additional layer of problems. I simply use one of the kids' Windows computers when I need to update firmware for peripherals or boot Windows on my Mac with Bootcamp. Even when a company offers a Mac version of the updater, it is usually more buggy and troublesome than the Windows version. This is certainly true for HP multi-function devices and various smart phones. The only exception is Apple peripherals like iPods.

For control, some mounts use standard interfaces allowing Mac programs to control them with a standard command set. I'm sure others have some experience with this.

I used a Vixen Sphinx mount for a few days (visual only) and it is very light weight for its level of stability. It is lighter and sturdier than my Celestron CG5-ASGT. It is nicely made with good fit and finish and easy & fast to set up. I found the Starbook controller a bit cumbersome to use, but it gets the job done (with firmware version 2.1). It is probably the most modern design of any of your candidates, and it has nice touches like a retractable counterweight bar (slides inside the mount so you don't have to attach or remove it), and motors located where they serve as counterweights (so you can reduce the CW weight needed).

#4 Phil Cowell

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Posted 11 July 2009 - 06:52 PM

You'd only need to go to WinDoze to perform updates to the mount or use another machine for updates. Apart from that The AS-GT or the CGEM and Astroplanner on the Mac add your imaging software and your good to go.
Phil

#5 Renae Gage

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Posted 12 July 2009 - 08:28 AM

Hmmm...a couple of recommendations for an ASGT, which is "less mount" than I anticipated I would need. Does this mean that I need to also consider the Orion Sirius?

Does ANYONE have AP experience with the Sphinx?

#6 adamsp123

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Posted 12 July 2009 - 09:44 AM

Hmmm...a couple of recommendations for an ASGT, which is "less mount" than I anticipated I would need. Does this mean that I need to also consider the Orion Sirius?

Does ANYONE have AP experience with the Sphinx?


I have use my Sphinx with both my 120ED and Meade 10" SNT which at 29 pounds weight should be too heavy for the mount, but hey with the supplied 2 and 1/2 counterweights I could get balance and get unguided subs for 1 min although it was better at 30 secs which with the F/4 meade was OK, results were absolutely fine, I have now got an Atlux for AP but I will be keeping the sphinx do to ease of use and lightness.

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#7 adamsp123

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Posted 12 July 2009 - 09:48 AM

Here is a photo taken of M51 using the sphinx+SNT 20 x 30 sec subs unguided

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#8 Renae Gage

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Posted 12 July 2009 - 11:52 AM

adamsp,

I could live with that! Nice shot!

Eric

#9 Luigi

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Posted 12 July 2009 - 05:29 PM

I'm sure the Sirius would work well but the ASGT/CGEM hand-controller software is superior to that of the Sirius and Atlas mounts. Many use a PC laptop running mount control S/W (name escapes me for the moment) to run the Sirius and Atlas mounts. I do not believe there is Mac S/W available.

#10 Renae Gage

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Posted 12 July 2009 - 06:16 PM

I'm starting to lean a little harder toward the Sphinx:

1. Light weight
2. Fewer software issues
3. Innovative design--I like to support those manufacturers who are pushing the envelope.
4. Apparently adequate to the task as described.

#11 zoran

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Posted 13 July 2009 - 02:32 AM

Hello!
I'm using GM-8 for guided AP, and I'm reasonably happy with it. But, if you intend to do unguided AP, you'll probably need something more precise.
I am also one of unlucky people who doesn't have permanent setup, but I try not to set up my gear from the scratch each night. I've bought Telegizmos covers for the tripod and the scope, so if I have couple of days of good weather I just leave my setup outside assembled and covered. That saves lots of time and effort. Of course, if the weather starts changing for the worse I disassemble all the stuff and take it inside.
Best regards,
Zoran

#12 Renae Gage

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Posted 13 July 2009 - 10:01 AM

You raise a good point. I have a lot of land and dark skies. I should probably just sink a pier. It would make any mount better. My old GM-8 was always limited by the tripod, not the mount.

#13 donsinger1

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Posted 14 July 2009 - 05:24 PM

Eric:

I would go with either the GM8 or Celestron CGEM. Nothing in the price range you are looking at will give you very acceptable images with 1 minute unguided exposures. For the time that you will waste trying to figure it out, it would be cheaper to get a small guidescope like a Miniborg and do guided shots with PHD guiding.

Check out the Vixen groups on Yahoo...they have a lot of software problems with good guiding, more than what I saw with the Gemini or Celestron units. The beauty of Celestrons hand controllers is the polar alignment routine which is great for those of us who have to setup more often than not (no permanent location).

I had a GM8 with Gemini goto and like it a lot. But, I wanted something more dead dumb simple capable of carrying more weight, and the CGEM fits the bill nicely.

Don

#14 Luigi

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Posted 15 July 2009 - 07:12 AM

Why bother with unguided for DSOs? You can put in a ton of effort and spend a fortune trying to get a mount that will work unguided and it still won't be as good as a guided inexpensive off the shelf the mount with mediocre polar alignment.

I am by no means an expert on hand mount firmware, but it seems Celestron's is the most sorted of all the manufacturers', including the premium ones.

#15 Patrick

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Posted 15 July 2009 - 09:18 AM

Hi Eric and welcome to the wonderful world of AP!

Any of those mounts will do a good job for wide field astrophotography using your TV85. I personally would lean towards the CGEM because of the polar alignment routine.

The alternative to Celestron's polar alignment routine is a drift alignment and if you hate complicated, you'll hate drift aligning. On average it took me about 45 minutes to an hour to drift align and then do a goto alignment prior to snapping my first image. With Celestron's new firmware upgrade, the goto alignment incorporates the polar alignment process, and the whole procedure is cut to a third of the time.

If you want to keep things really simple, a standard Vixen GP2 mount with polar alignment scope and drive motors and controller is very capable of giving you 1 minute unguided exposures with your TV85. The polar alignment scopes are more accurate than those found on Celeston's mounts. That's probably the least hassle and accurate setups available. Of course you won't have goto, but if you're doing widefield AP, then it's not that much of an issue. However, one additional comment...while the focal length of the TV85 is relatively short, it's not what I'd consider 'widefield'. Have you considered starting out with short focal length camera lenses like 24mm to 100mm?

Patrick

#16 waassaabee

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Posted 15 July 2009 - 05:39 PM

CGEM - Solid, accurate, ST-4 autoguide port, easy to set up, easy to align. I have done 2 minute subs unguided, with the guide setup the sky is the limit.

#17 Renae Gage

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Posted 16 July 2009 - 11:00 PM

Have you considered starting out with short focal length camera lenses like 24mm to 100mm?


Patrick,

Absolutely! I'll use the GEM to mount the camera for widefield shots as "Project #1". Once I get the hang of that, I'll start stretching the focal length.

Eric

#18 Taylor

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Posted 17 July 2009 - 01:17 PM

I'll give a vote for the Sphinx, check your PMs.

#19 Kolenka

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Posted 17 July 2009 - 02:12 PM

You can get USB to serial port adapters but they require drivers (Windows only of course) and can be unreliable.


As another Mac user, I can name a couple brands that work great on my Intel Mac, and have on my PPC Macs before it. Yeah, they need drivers, but I bookmark the driver vendor for these guys for just this reason, as their Mac drivers are in one spot, but not always the easiest to find when Googling for them.

The CGE I had before getting the CGEM was probably the most Mac-friendly mount I've used, simply because it works so well with VMWare for firmware updates. By the sounds of it, the Vixen should do fine as well, since VMWare's networking is also just fine too.

The fact that the Meade/Celestron mounts take a pretty standard serial port protocol to control them makes it fairly easy to write tools that talk to them. I know AstroPlanner will give you some level of laptop-based control of a CGE/CGEM via serial on the Mac side so you don't need Windows.

I've not seen if laptop control of the Vixen is possible without booting up Windows.

EDIT: I'm starting to think a guide of "AP for Mac Users" may be in order. I run my entire imaging rig from OS X, but it did take quite a bit of hunting and searching, as none of the information was all in one place.

#20 Renae Gage

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Posted 17 July 2009 - 11:36 PM

EDIT: I'm starting to think a guide of "AP for Mac Users" may be in order. I run my entire imaging rig from OS X, but it did take quite a bit of hunting and searching, as none of the information was all in one place.



Oh...please do!!

#21 Luigi

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Posted 18 July 2009 - 07:10 AM

Not only is the Sphinx much lighter than the CGEM, it also considerably lightens your wallet compared to by buying a CG5ASGT, which is arguably at least as capable but lacking in cachet, IMO.

#22 Renae Gage

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Posted 18 July 2009 - 10:50 AM

I have found that the most expensive equipment in the long run is the stuff that disappoints me. Those items that are a joy to use are generally worth every penny. I am hoping the Sphinx will be one such product for me.

#23 Luigi

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Posted 18 July 2009 - 12:19 PM

Yeah, I know what you mean...I think. Did you get it with the hal-130 tripod? Let us know how that works.

#24 Renae Gage

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Posted 18 July 2009 - 04:36 PM

Yes, the 130 without the half-pillar for the time being.

#25 Taylor

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Posted 18 July 2009 - 05:32 PM

I recommend the pillar once the sticker shock of the initial mount wears off.
It gives some nice clearance for any cables like dew heater lines and imager control cables when the mount is swinging around.
Also, I love having the storage in the little cubby inside it, very handy.






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