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Mount for 6" RC?

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#1 wavecloud

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Posted 23 September 2013 - 12:26 PM

What kind of a mount is tood for a 6" RC astrograph?

#2 jbalsam

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Posted 23 September 2013 - 01:10 PM

There are several mounts that I know of that are suitable for this. I personally use a celestron CGE mount (with a guidescope), which would be more than fine for a 6" RC scope (a used CGE goes for around $1600-2000). The newer CGEM mounts are also quite capable of these longer exposures when guided, and they're a bit cheaper I think. Losmandy's GM8 or G11 mounts would also be great choices (a bit more expensive, as far as I've seen, but they seem to last forever and retain their value). I've also seen people get good results using the Atlas mount. If you have some extra coin lying around, you could also get a used astro-physics mount (the AP-400 ($3-4k) would probably work fine, and the mach1 ($6-8k) or larger definitely would). They're great mounts, and they seem to never lose much value, so you can always resell it later.

If you go on astrobin.com and search for AT6RC you'll see lots of photos that people take those scopes, and they usually post in the details of the photos what mount they use. Be warned, however: lots and lots of people buy that scope because it's relatively cheap and they post their pics on astrobin, and most of them are not great. Don't be discouraged by that. The scope is capable of great images, but it's an f/9... so you'll need long exposures which means you'll want a decent mount and an autoguider (OAG or a guide scope, whatever floats your boat). You will very likely need to be taking images that are 10mins or longer, especially if you want to get into narrowband imaging.

All that being said, is this the first scope you are going to try doing astrophotography with? I only ask because it can be tough to get good results starting off with a slow scope like this if you're trying to image deep sky objects. You can increase your chances of having fun by starting off with a faster scope (something like an f/6-ish apo or ED refractor), or getting a focal reducer for the 6" RC (the astro-physics CCD-T67 reducer apparently works quite well with these scopes). That will speed you up to around f/6, which will shorten your exposure times and make the learning curve a bit easier.

#3 andysea

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Posted 23 September 2013 - 02:56 PM

I briefly tested the CCDT67 with the At6RC and it does work well. Another advantage of using the focal reducer is that the it will make tracking/guiding errors less prominent.

#4 rigel123

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Posted 23 September 2013 - 10:14 PM

An Atlas mount and the Orion Mini Guide setup work well with the AT6RC. I go between my RC and my ED80T depending on the object or FOV I desire.

You can see my results on the Astrobin site in my signature.

#5 T1R2

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Posted 23 September 2013 - 11:30 PM

Whats your budget??

#6 wavecloud

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Posted 24 September 2013 - 11:14 AM

Whats your budget??

Hard to say preciseley at the moment, but no more than 3000-4000.
I defineteley can't afford an Astro-Physics mount, though. :p

#7 jbalsam

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Posted 24 September 2013 - 11:43 AM

For 3-4k you could do very well with a used GM-8, and have plenty of cash left over to buy yourself the other bits you'll need (guide scope or OAG and an autoguider, etc etc). Here's one on astromart for $1400, and it comes with the gemini add-on: http://www.astromart...ified_id=832480

#8 wavecloud

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Posted 24 September 2013 - 11:55 AM

Very helpful all, thanks.
I'll look into that.

#9 orlyandico

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Posted 24 September 2013 - 12:03 PM

There's a Takahashi NJP Temma 2 on Amart right now for 3.8K.

If you have the 4K jump on that; they only come up for sale a handful of times in a year. It will probably be the last mount you'll ever need - 70lb capacity. It will also bust your ***** with the weight, but it's made to last a lifetime.

#10 wavecloud

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Posted 25 September 2013 - 10:47 AM

What, exactly, is the Gemeni add-onn?

#11 orlyandico

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Posted 25 September 2013 - 11:40 AM

Losmandy GM8 and G11 don't have GoTo in the base model. You need to buy the Gemini separately to get GoTo.

But as I said - if you can swing the $3.8K forget the GM8 and G11, get the Tak. It'll be the last mount you'll ever need (unless you want to go fully robotic, in which case you'll be spending at least double that).

The G11 is a fine mount, but it is not a great mount. As someone who's wasted money buying sub-standard and just-OK mounts, buy the absolute best and you'll never regret it. Better yet at $3.8K (compared to over $10K for the Tak EM400 that replaced it in Tak's lineup) it is so depreciated that you can resell it for pretty much what you paid.

I've only seen Tak NJP's come on sale 5-6 times a year. Something to keep in mind.

#12 wavecloud

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Posted 25 September 2013 - 12:04 PM

3k-4k is the *** Abslute Maximum*** I can afford to spend, I'm not so sure about the Tak. 2k is much more realistic.

#13 orlyandico

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Posted 25 September 2013 - 12:16 PM

ah, well in that case.. try to find a G11 with Gemini 1. Lots of people have had good results with that, others not so much. Or an Atlas/EQ6, much less money and still decent-ish.

Don't take my word for it though. I don't want to make any recommendation that may backfire or end up not meeting your expectations.

#14 wavecloud

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Posted 25 September 2013 - 12:39 PM

"Decent-ish"?

#15 orlyandico

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Posted 25 September 2013 - 01:11 PM

YMMV but I consider any mount of G11 class or less to be merely decent. Others will certainly disagree. But when you read about the folks on this very forum who spent $3K+ for a new G11 and are now shopping for an upgrade.. makes you think.

#16 wavecloud

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Posted 25 September 2013 - 01:32 PM

YMMV but I consider any mount of G11 class or less to be merely decent.

What do you mean by "mereley decent"?

#17 Falcon-

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Posted 25 September 2013 - 03:49 PM

YMMV but I consider any mount of G11 class or less to be merely decent.

What do you mean by "mereley decent"?


Orlyandico has fairly high standards. ;) He is undoubtedly correct, the mounts he prefers are superb (and it is always worth getting the best mount you can afford), but the Atlas/EQ6-class and G11-class mounts are in quite common use for imaging setups.

I am using a 6" f/9 RC (the AT6RC) on an old Celestron CI-700, the G11 is equivalent or slightly better then the CI-700, I would consider A G11 quite capable indeed for the task at hand!

Previously I attempted to use the same AT6RC on a CG5 ASGT - that was not successful, DEC guiding issues drove me nuts. I know others have better luck with the CG-5 but even so I would stay away from that class of mount with the *possible* exception of the ZEQ25.

#18 wavecloud

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Posted 25 September 2013 - 05:12 PM

Are the Atlas/EQ6 mounts fairly similar to the G11?

#19 orlyandico

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Posted 25 September 2013 - 07:47 PM

The G11 is a better class, it's probably the most popular "mid grade" mount.

My beef with the G11 is that for the price - particularly new at over $3K with the Gemini 2 - there are a disturbing number of unhappy users.

The Atlas/EQ6 is $1.5K new (and $900 - $1K used) so a fair degree of disappointment there is expected. But at $3K+ I would disagree.

You can search this forum for the people who are disappointed with their G11's and looking for something better.

So, although the G11 is a better mount than the Atlas/EQ6, I would avoid buying one new. If you can get a Gemini-equipped one for under $2K and it has the one-piece worm block then it's probably a good buy. I say probably because you still risk having issues.

#20 rigel123

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Posted 25 September 2013 - 08:18 PM


The Atlas/EQ6 is $1.5K new (and $900 - $1K used) so a fair degree of disappointment there is expected. But at $3K+ I would disagree.


I don't know that I see many posts about being disappointed in the Atlas, unless it is about the Altitude adjustment bolts which can be remedied easily.

#21 orlyandico

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Posted 25 September 2013 - 09:37 PM

well TBH Warren I don't have an Atlas, I'm simply assuming that the user experience is the same/similar to the CGEM, which I did have, and which I was disappointed with.. of course the Atlas doesn't have the 8/3 and declination cogging, so it's probably less of a disappointment than the CGEM.

I'm not trying to be a troll here. I know a lot of people enjoy success with g11s and Atlas mounts. But you do hear about problems as well. While with the premium mounts you practically never hear this.

Also, the OP said he could pay up to 3-4K. In my own (painful) experience, cutting corners here will bite you in the future. If the OP had said he could only pay 1K then I would have said get an Atlas, it's that simple. We all have budget constraints.

But since he indicated he could spend more, this is where my recommendation is coming from. That Tak is (was?) a very good deal for what you get.

#22 wavecloud

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Posted 26 September 2013 - 10:08 AM


Also, the OP said he could pay up to 3-4K. In my own (painful) experience, cutting corners here will bite you in the future. If the OP had said he could only pay 1K then I would have said get an Atlas, it's that simple. We all have budget constraints.

But since he indicated he could spend more, this is where my recommendation is coming from. That Tak is (was?) a very good deal for what you get.


Actually, orlyandico, I said "definitely no more than 3k-4k" which means (to me) that I only can go there if absolutely neccessary i.e. no other reasonable options. I akso said that 2k is much more realistic, and I didn't say that if I don't want my budget washed away by the rising Highwood River, Alberta in June 2013 :lol: 1k--.5k is more like it.

#23 orlyandico

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Posted 26 September 2013 - 06:01 PM

well I was in that position.. I could stretch to buy a better mount but I didn't feel like it so I cut corners. I ended up buying two less-than-perfect mounts, sold one of them at a big loss because it didn't meet my expectations. Still have the other one that I use as a test bed for various DIY stuff. Ended up buying the perfect mount (in the end). So wasted money on the first two.

#24 wavecloud

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Posted 26 September 2013 - 07:21 PM

The question here is: what were your expectations?
I'm not sure if I [b]can[b/] stretch :undecided:
But I'm open to as much advice as I can get :thanx:

#25 orlyandico

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Posted 26 September 2013 - 07:55 PM

My expectations were consistent round stars with guiding at 10 minute subs at a 900mm focal length. Sadly, neither the CGEM nor the AP600 could achieve this reliably - the CGEM because of its huge periodic error, 8/3 and cogging, and the AP600 because of a sticky declination axis (in spite of its fairly low RA periodic error).

Since you say you're using a 6" RC, that is a lighter OTA than I was using but it has a longer focal length. I would say it is a tougher OTA to use than my 100mm f/9.

So YMMV. What I know is, with the two mounts I mentioned above, I could not achieve my - in my opinion modest - expectations. But given that you don't want to go buy a premium mount - even one with a huge discount - I really suggest buy an EQ6, try to find a used one under $1K. That way if it doesn't meet your expectations you can sell it at a minimum loss. Avoid buying new, mounts depreciate like heck. I have a sneaky suspicion an EQ6 would perform better than my ($2K used!) AP600, simply because the EQ6 has ball bearings in the DEC axis.

And avoid the CGEM and its cousin the CGEM DX.

You will need to futz around with the worm engagement, tinker here and there, ensure you are east-heavy in RA, balance your DEC, etc. You will never be able to get rid of backlash in DEC, so if a wind gust comes along it will take forever for the guiding to recover and you probably will throw that sub.

All things that I no longer have to do and still get round stars at 20 minutes - everything is tight, the mount reverses instantly in DEC.. It is that consistency, reliability, and insensitivity to minor imbalances etc. that you get when you buy premium.






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