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sphinx SXW ? over atlas or cgem

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#1 nebultick

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Posted 01 November 2012 - 05:35 PM

I was thinking about getting an atlas or CGEM. I know the pros and cons of both these mounts because the subject has been beaten to death. I was leaning heavily towards the atlas due to the dec motor issues with the cgem.

But i noticed the vixen sphinx swx is $1899 i thought it was more. Vixen's site claims 35 pound capacity and the mount is very very light 15 pounds. Also starbook looks interesting.

I want a new mount for astrophotography only, i will pretty much never just being looking through it. I will be using a St80 with an SSAG, an orion ed80 with a canon T3. Side by side adm saddles. And i may plan on getting a 6" or 8" astro tech RC.

setup speed and fast polar alignment are a priority for me. Due to light pollution i'm limited to 5-6 min exposures with a LP filter and 3 without.

#2 Raginar

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Posted 01 November 2012 - 05:49 PM

Google them. I think they have similar issues to an Atlas or CGEM class mount. However, based on the equipment load, I don't think you'd be unhappy with an Atlas or CGEM either. BL: The Sphinx is not a 'better' mount despite costing more.

#3 neilson

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Posted 01 November 2012 - 08:57 PM

I have a CGEM DX and mine doesn't have Dec. issues. But I hear they are working on a firmware fix for those who do have the DEC cogging problem.

neilson

#4 orlyandico

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Posted 01 November 2012 - 10:23 PM

The Sphinx SXW is not comparable at all payload wise to the Atlas or CGEM. Even the SXD is good for at most a 20lb imaging load. So I'd say the SXW is at best 15lb.

Not to mention the Sphinxes also have declination guiding issues.

#5 EFT

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Posted 02 November 2012 - 10:12 AM

The Starbook is apparently not good for astrophotography use so a fair number of people who want to use the Sphinx for astrophotography end up trading out the electronics for a system that allows for the use of the Celestron Nexstar hand controller. The amount of wieght you want to put on it might be a load for the CGEM/Atlas and would certainly be over the top for the Sphinx.

#6 orlyandico

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Posted 02 November 2012 - 10:46 AM

i think the SXW can handle a 6" AT6RC. definitely not the 8".

you will need the NexSXW board upgrade. otherwise you will get random declination jumps that will ruin your day.

#7 Ranger Tim

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Posted 03 November 2012 - 11:51 AM

The Sphinx? Add extra $$$ for the NexSX IC board, wait for it to get here from Spain, install and purchase a Celestron hand control. You will then have a very reliable AP imaging platform. The Sphinx SXW does not work well for imaging unless you replace the StarBook with the NexSX board. Those that have done so love the mount.

The weight capacity of the SXW is about 15 lbs. for imaging. You may be able to eke out another 3 or 4 lbs. if you are lucky.

This mount broke my heart. There is so much going for it; 1) Probably the best polar scope on the market, 2) Fit and finish is excellent, 3) the StarBook interface is a good concept, 4) the tripod is super light but really rock solid, 5) the whole rig is lightweight, 6) the StarBook has an ethernet connection for scope control/router connection, 7) excellent adjustment for guiding sensitivity and backlash compensation.

Here's where Vixen dropped the ball; 1) The StarBook has a limited ability to display much detail, 2) and has a limited database of star catalogues, 3) the software insists on introducing random declination movements at least every couple of minutes, 4) parts must arrive by slow boat from Japan, 5) the StarBook does not have enough adjustment in screen brightness (you will blind those around you) so you must use extra screen filters, 6) guide scopes must make electronic connection to the StarBook not the mount chassis, 7) the mount doesn't like very cold temps (stalls, StarBook screen problems, etc.

Buy the Atlas and you will be happy until you can afford a higher tier mount (Losmandy, AstroPhysics, etc.).

#8 mayidunk

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Posted 03 November 2012 - 02:06 PM

Tim, does careful polar alignment mitigate against the DEC moves that tend to ruin exposures?

I have a Sphinx SXW, and love it! However, it's strictly being used for visual, so the Starbook is more than adequate. I can also control it using Cartes De Ciel with an ASCOM driver. This seems to work really, really well, though i have not yet used it in the field! However, testing it in the house shows that the scope will go to whatever compass points the software sends it, as well as seeming to go to whatever ALT value the software tells it to go.

#9 orlyandico

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Posted 03 November 2012 - 02:26 PM

i believe that even if you don't do an align (e.g. just turn the mount on, so no GoTo's will work) the sphinx will randomly jump in declination.....

#10 mayidunk

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Posted 03 November 2012 - 02:39 PM

Interesting, as my thinking is that if it's tracking an object and believes that its orthagonality is off, it'll attempt to dial in DEC corrections from time to time, but in doing so tend to not be able to stay put after the DEC move, tending to jump around a bit for short periods. At least, that has been my understanding, which I admit is a bit hazy and incomplete due to it not being especially interesting to me since I'm not doing AP.

#11 mayidunk

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Posted 03 November 2012 - 02:41 PM

I do have to say that when using it visually, I have not ever noticed it jumping in DEC once it settles on an object. Not to say it never happened, but that I don't remember it ever happening.

#12 orlyandico

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Posted 03 November 2012 - 09:52 PM

based on what i've seen the jumps are around 20 arc-seconds.

probably not visible through an eyepiece but more than enough to thoroughly ruin your day when imaging.

#13 rmollise

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Posted 04 November 2012 - 08:31 AM

If you have even the slightest desire to do imaging or use a heavier OTA, do yourself a favor and get the Atlas. No, it doesn't have the fancy StarBook, but it is reliable and capable. Oh, and it is likely we will be able to purchase Synta's version of the StarBook, the SynScan Tour, for use with the Atlas before long if that is what has got your attention... ;)

#14 rmollise

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Posted 04 November 2012 - 08:33 AM

20" would most assuredly be noticeable--and annoying. ;)

#15 Ranger Tim

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Posted 04 November 2012 - 10:34 AM

If you are in the field imaging you become attuned to how the mount sounds. It was in this capacity that I first heard the tell-tale tic-tic-tic sound of the Sphinx moving the dec when it should have been simply tracking in RA. Yes, I polar align and then drift align very carefully when I image. There have been times that the Sphinx has performed without the dec movement, but these have always been the exception rather than the rule. I have tried all of the suggested techniques, i.e. don't create a pointing model, etc. to no avail. After two years of using this mount I gave up and obtained a Losmandy GM-8 which has cured the problem.

I still use the Sphinx for outreach and star parties because it is a fun visual mount and it is light weight. My computer can synch with it via a router wirelessly with SkySafari and it is a blast to use with my six inch f/6 newtonian. But for AP it is an exercise in frustration. At some point I will buy the NexSX electronics board for it just to make it a viable, portable AP mount. This would be a great set up for a small widefield refractor or six inch RC, and I could get it into the trunk of the Miata!

To all those who want to purchase the StarBook equipped mounts for AP - You have been warned! I second Rod's advice about going the Atlas route for under $1500.

Here is a pic of the pretty Sphinx. It is the siren song that I fell for when I was looking for my first AP mount. One day this will have a Celestron controller, but it will not be used for any AP until then.

Attached Files



#16 Ranger Tim

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Posted 04 November 2012 - 10:37 AM

Here is the Sphinx dec jump on PHD graph.

Attached Files



#17 Steve Drapak

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Posted 04 November 2012 - 02:58 PM

I don't know about the Sphinx, but you can definitely do imaging at at least the Atlas' maximum load spec, it can be loaded more heavily than other mounts in it's class. I've had a Meade 12" ACF on one for two to three years now with no issues. I use it 100% for imaging and get nice round stars (if I get the autoguiding and everything else right).
Definitely need an off-axis guider, separate guide scope will result in flex.
Steve

#18 rmollise

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Posted 04 November 2012 - 03:09 PM

Here is a pic of the pretty Sphinx. It is the siren song that I fell for when I was looking for my first AP mount. One day this will have a Celestron controller, but it will not be used for any AP until then.


And it is pretty and I still want one. If ONLY Vixen would learn to listen to their customers. :bawling:

#19 orlyandico

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Posted 04 November 2012 - 09:51 PM

funny thing is i know someone with an SXP (starbook ten) and he thinks the declination jumps are still there!

#20 rmollise

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Posted 05 November 2012 - 07:41 AM

funny thing is i know someone with an SXP (starbook ten) and he thinks the declination jumps are still there!


That is really sad. :mad:

#21 mayidunk

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Posted 05 November 2012 - 11:51 AM

Seems the software for the first Starbook was written by a guy who basically fell off the face of the Earth after he wrote it! From what I understand, this kept Vixen from being able to make the software changes that might have made the SXW/SXD mounts more suitable for AP.

I believe the Starbook 10 uses newly written software, especially as they're now using stepper motors in the SXP/AXD mounts instead of servo motors, as in the older SXW/SXD mounts. That being the case, the DEC jumps being caused by the old software shouldn't exist in the new... but then again, I could be mistaken.






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