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Direct Drive mounts for non-imagers?

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#1 islandsteve11

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Posted 11 February 2010 - 04:00 PM

OPT is now offering 2 models of direct drive mounts (DDM) made by ASA of Austria. The smaller model is priced $50 less than an AP1200 with a weight capacity between an AP900 and AP1200 while offering better tracking performance. Hopefully, this gear-less technology will eventually trickle down to much more modestly priced models in the G11/CGE class before the decade is out (and dare I say it, even the CGEM/Atlas class).

Other than for those that simply have to have one, are there any tangible benefits of DDM technology to the non-imager aside from (hopefully) lowering the prices of older technology mounts? More specifically, would DDMs be more portable (smaller, lighter, more compact) more reliable (fewer moving parts = more reliable & durable?), or more user-friendly (easier set-up/polar alignment) than current mounts?

The accuracy of my CG5-ASGT ($525 new) is more than adequate for visual observing. Just wondering what people think.

Clear Skies,
Steve

#2 jrbarnett

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Posted 11 February 2010 - 04:05 PM

"Hopefully, this gear-less technology will eventually trickle down to much more modestly priced models in the G11/CGE class before the decade is out (and dare I say it, even the CGEM/Atlas class)"

I doubt we'll see direct drive mounts targeted at visual users until direct drive technology has completely replaced gears technology in equatorial mounts. As you've suggested, a geared mount is more than adequate for visual use. Bigger geared mounts for visual users allow larger OTA payloads. No need for bigger and more accurate for visual use.

I suspect it will be 20+ years before direct drive mounts replace geared mounts at the high end for imagers. Maybe never for visual only users.

Cheers,

Jim

#3 Cyclop_si

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Posted 11 February 2010 - 04:07 PM

ASA DDM mounts came without handcontroller, you need computer. This is no problem for imaging (you need guiding, CCD capturing, etc anyway), but unconvinient for visual.

#4 islandsteve11

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Posted 11 February 2010 - 05:48 PM

Personally, I hope DDMs get a little boost this decade if GM would move beyond the concept stage for it's hydrogen fuel cell cars using their "skateboard" chasis. A post in another thread mentioned the auto industry is looking at direct drive motors to power each wheel - now we're talking economy of scale. How exactly it would extrapolate into DDM sales remains to be seen.

#5 hudson_yak

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Posted 11 February 2010 - 08:08 PM

I wonder what the power requirement for this technology is. It seems possible it could draw a good bit of current simply to hold position firmly, particularly if the load is not perfectly balanced about each axis.

For visual use I'd want it to have some sort of dynamic clutch design so you could, with adjustable force, push the scope around. Same usage concept as the Losmandy slipper clutches though integrated into the drive system itself.

And yes, the price would have to be reasonable...

Mike

#6 islandsteve11

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Posted 11 February 2010 - 09:02 PM

I wonder what the power requirement for this technology is. It seems possible it could draw a good bit of current simply to hold position firmly, particularly if the load is not perfectly balanced about each axis.


According to the specifications on OPT's website for the small ASA DDM, it has a rated capacity of ~25 kg and runs on "12V/<10A (0,4-0,8A Tracking)." It gives no further details.

#7 gnowellsct

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Posted 11 February 2010 - 09:57 PM

Well I watched the video and it looks impressive. Wolfgang Promper is involved and that means this is a super-serious product. Greg N

#8 David Pavlich

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Posted 11 February 2010 - 10:25 PM

If you don't mind spending that kind of money for a visual only mount, go ahead. But if your budget isn't that large, I'd first ask what kind of load will it be carrying and will it be in an observatory or will you be moving it around alot?

For visual, anything under 40lbs could be handled very nicely by an Atlas or CGEM for about 1/5 the cost. It makes no sense to me to buy a really high end mount for visual, but that's only my budget minded opinion.

David

#9 mish

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Posted 11 February 2010 - 10:34 PM

For visual, anything under 40lbs could be handled very nicely by an Atlas or CGEM for about 1/5 the cost. It makes no sense to me to buy a really high end mount for visual, but that's only my budget minded opinion.


I agree completely, especially given that other 4/5 of the cost could be used to purchase some excellent optics.

For visual observing, wouldn't money be better spent on the part of the telescope that connects to our eyes instead of being used to chase down a few extra arcseconds of otherwise-invisible periodic error?

#10 CounterWeight

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Posted 12 February 2010 - 03:01 AM

Steve, the CG-5 is a great lil mount.

What if you want visual with a BIG scope - or a long BIG scope or a big-long scope? If the mount payload is heavy or long moment and heavy - there are very few options, few enough to be more just a choice between a and b and c (and if they even have one to sell you when you want it) ... what direct drive opens up is the this area for big scope owners... and really for price - it is already somewhat competitive. The lossyness or power drain is just an artifact of using current - same goes for your toaster and microwave and frigde/freeze.

What we have at present is mid to late mid century motors and cogsmade better by late century software, and manufacturing methods.

The direct drive and or harmonic direct drive is the first real departure from this outdated worm gear/cog gear mechanical situation. The software/firmware is already there. Direct drive motors are really amazingly simple - hystresis and magnets - pretty darn well characterized as far as my experience goes. For that matter so ar fiber-optic gyro's :) I'm really, really happy ASA and Chronos are already putting mounts out there. Other than mystique value and all that... the larger AP's and Tak's and Paramounts are already outdated and specwise clearly outgunned for the heavy lifting by these initial offerings.

The design is simplicity itself and easily scalable. There may be a point where the old style mechanical may remain more price competitive, or even a hybrid design. Thankfully scope drives are only single axis movement (times 2 for EQ mount) and invite this technology.

I think the real problem becomes how to charge the current arm+leg for a heavy lift mount that has very lttle to it after the initial design and tool-up. :confused:

#11 Phil Cowell

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Posted 12 February 2010 - 05:38 AM

If you don't mind spending that kind of money for a visual only mount, go ahead. But if your budget isn't that large, I'd first ask what kind of load will it be carrying and will it be in an observatory or will you be moving it around alot?

For visual, anything under 40lbs could be handled very nicely by an Atlas or CGEM for about 1/5 the cost. It makes no sense to me to buy a really high end mount for visual, but that's only my budget minded opinion.

David


I agree on the budget point and as far as imaging goes the following could be countered. As a tax payer I'm already paying for Hubble and other observatory images, why try to compete? They are online and we all have internet access or we wouldn't be here.
If we all thought about only using what was purely needed the majority of us would be taking public transport.

#12 Charlie Hein

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Posted 12 February 2010 - 07:05 AM

If you don't mind spending that kind of money for a visual only mount, go ahead. But if your budget isn't that large, I'd first ask what kind of load will it be carrying and will it be in an observatory or will you be moving it around alot?

For visual, anything under 40lbs could be handled very nicely by an Atlas or CGEM for about 1/5 the cost. It makes no sense to me to buy a really high end mount for visual, but that's only my budget minded opinion.

David


I agree on the budget point and as far as imaging goes the following could be countered. As a tax payer I'm already paying for Hubble and other observatory images, why try to compete? They are online and we all have internet access or we wouldn't be here.
If we all thought about only using what was purely needed the majority of us would be taking public transport.


I know that you meant this in a tongue-in-cheek sort of way, but I have actually heard this argument from someone who was totally serious about it. They couldn't see the value of amateur astrophotography because it's bested elsewhere and freely available to everyone.

#13 Starhawk

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Posted 12 February 2010 - 12:11 PM

Actually, it's hard to imagine a better computer guided mount for the visual-only amateur than something like a Nexstar SLT through the NexStarSE and CG-5 computerized mounts, all of which are really cheap, and use a boatload less power than a DDM. Is DDM going to drive down the cost of conventional mounts? I sincerely doubt it. Did the introduction of the F-22 drive down the cost of the Cessna 172?

What's the real benefit of DDM? Well, at the moment it appears to be aesthetic. The required installation at this time means a permanent observatory, and at that point, none of the advantages for tracking or guidance are meaningful since the conventional mounts do it all for less money. OK, so how about the massive slew rates? That's pretty cool. Though if you want to drop the cash, conventional mounts do that, too. But what we are talking about are totally different markets.

So what is it here which is supposed to cause a reduction in cost. Is the NexStar 80SLT going to get cheaper than $300? It's already there. OK, so how about GEMs- you can get an CG-5 GT from Woodland hills or OPT for $575 right now. Are you really hamstrung because it is too expensive? You can get computer guided mounts more than adequate for visual use for less than a netbook computer, today. So what's the breakthrough to be had? I kind of feel like this is hoping for compact fluorescent lightbulbs to get cheaper; they are already in 6 packs for $6.50, so the cost revolution is over and they are cheap, now. Anyone who can afford to take the family to a movie four times a year can afford a computer guided telescope for visual use.

In short, there is no more enabling cheapness to be found, here. If you want a CG-5 GT, buy one. If they suddenly cost $300 instead of $575, are you going to buy more? Of course not. If they suddenly cost $1.75, will everyone run out and buy one? No.

Does the introduction of a new mount for use in high end permanent observatories change the cost of lightweight visual mounts? No. Will it? No. Did introducing Keck make C14 telescopes cheaper? No.

Take the current cheapness of mounts for visual use for what it is and get one, go observe, and be happy. And if someday it's possible to buy one for slightly less, you'll still only be out of pocket a few dollars, and the time you got to spend observing was worth far more.

-Rich

#14 islandsteve11

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Posted 12 February 2010 - 01:52 PM

I agree on the budget point and as far as imaging goes the following could be countered. As a tax payer I'm already paying for Hubble and other observatory images, why try to compete? They are online and we all have internet access or we wouldn't be here.
If we all thought about only using what was purely needed the majority of us would be taking public transport.


Huh? :bigshock: Is someone suggesting shuttering astro-imaging businesses and laying off all their workers? Do we need/want an AP nazi, I mean czar? :grin:

It's a conspiracy, undoubtedly led by the same vegans who want to ban beef sales because it's calorically inefficient to produce beef (beef itself has far fewer calories than the cow consumed to produce it), and because cows belch greenhouse gases. Every household should be required to compost their toilet waste and recycle urine for drinking water!

(My apologies if I've offended anyone with my twisted sarcasm.)

#15 Scruffy

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Posted 12 February 2010 - 01:53 PM

I watched the video and my first thought was "they ain't doing THAT with one of my scopes. Flipping around an instrument as critical and potentially delicate as an expensive 30 pound refractor should scare the poop out of any concerned owner.

Some things are best done slow... I'll leave it up to the reader to list a few, I have my list.

#16 islandsteve11

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Posted 12 February 2010 - 02:23 PM

I watched the video and my first thought was "they ain't doing THAT with one of my scopes. Flipping around an instrument as critical and potentially delicate as an expensive 30 pound refractor should scare the poop out of any concerned owner.


Unless the new technology is so unrefined (not ready for prime time) that the start up routine requires scaring the bejesus out of owners in order to properly seat the DEC and RA axes, I suspect it was done just to demonstrate the mount's range of motion and stability. Of course I could be wrong - I've only read the the most basic instructions in my ASGT's manual. :shrug:

Clear Skies,
Steve

#17 Phil Cowell

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Posted 12 February 2010 - 04:32 PM

I watched the video and my first thought was "they ain't doing THAT with one of my scopes. Flipping around an instrument as critical and potentially delicate as an expensive 30 pound refractor should scare the poop out of any concerned owner.


Unless the new technology is so unrefined (not ready for prime time) that the start up routine requires scaring the bejesus out of owners in order to properly seat the DEC and RA axes, I suspect it was done just to demonstrate the mount's range of motion and stability. Of course I could be wrong - I've only read the the most basic instructions in my ASGT's manual. :shrug:

Clear Skies,
Steve


It could be marketed as a scope saver routine, keeping rampaging hordes of children away from your scope when you make a pit stop during public outreach.

#18 Phil Cowell

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Posted 12 February 2010 - 04:40 PM

I know that you meant this in a tongue-in-cheek sort of way, but I have actually heard this argument from someone who was totally serious about it. They couldn't see the value of amateur astrophotography because it's bested elsewhere and freely available to everyone.


It was tongue in cheek but I'll bet there are a lot of large expensive mounts used for purely visual. Probably a lot more belonging to folks who tried imaging and then turned the camera into a flower pot with a lump hammer in frustration. They now use their mounts for purely visual.
I'm guessing 18 months to 2 years and a DD or harmonic will be putting the CGE Pro in mothballs here.

#19 Coromandel

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Posted 12 February 2010 - 05:20 PM

I watched the video and my first thought was "they ain't doing THAT with one of my scopes. Flipping around an instrument as critical and potentially delicate as an expensive 30 pound refractor should scare the poop out of any concerned owner.

Some things are best done slow... I'll leave it up to the reader to list a few, I have my list.


Which video? If you mean the Astelco vid, with the guy asking whether the Celestron would survive, it was not a good example in this case, because the Astelco NTM-500 is suited to users who need super high slew rates, such as those chasing GRBs.

The ASA DDM mounts do not slew as rapidly as the NTM-500 if I understand it correctly, and their power consumption figures are hugely lower as a consequence.

Having said even that, those people using the Astelco mount don't break their telescopes, even when rapidly slewing, so it's simply a case of looking much scarier than it actually is.

#20 Starhawk

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Posted 12 February 2010 - 11:03 PM

ASA says 15 degrees per second minimum, and faster if you ask. If you have a wire growing taught or an unforeseen interference, you had better be on your toes.

-Rich

#21 Coromandel

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Posted 13 February 2010 - 01:35 AM

ASA says 15 degrees per second minimum, and faster if you ask. If you have a wire growing taught or an unforeseen interference, you had better be on your toes.

-Rich


A slow slewing rate is one thing some mounts (ie cheap ones) often get criticised for!

The cable management system of ASA mounts appears to minimise any risk of damage.

IMHO, if you buy something like an ASA mount yet still practise sloppy cabling habits then you probably need to step back and rethink the way you do things.

:grin: ;)

PlaneWave's new direct drive mount looks interesting.

PlaneWave

It uses large three phase AC motors, but no word on the power consumption or slew rates.

#22 Starhawk

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Posted 13 February 2010 - 03:20 PM

Yeah, that point of view has quite the track record.

-Rich


A slow slewing rate is one thing some mounts (ie cheap ones) often get criticised for!

The cable management system of ASA mounts appears to minimise any risk of damage.

IMHO, if you buy something like an ASA mount yet still practise sloppy cabling habits then you probably need to step back and rethink the way you do things.

:grin: ;)

PlaneWave's new direct drive mount looks interesting.

PlaneWave

It uses large three phase AC motors, but no word on the power consumption or slew rates.








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