Paramount ME II or ASA DDM85 Basic

[jaspalchadha]

Paramount ME II or ASA DDM85 Basic people ??

[Astroscot2]

Yeah !

[perfrej]

You cannot look at those two and NOT look at 10Micron's offerings! I had the Paramount and the DDM on my short list and finally chose 10Micron GM2000HPS. I have since got myself another one, the GM1000HPS. Both are excellent and give you unguided tracking. That is something the Paramount cannot do, but the DDM can.

You have a few important parameters to consider in my view:

Mechanical considerations

All are of excellent mechanical quality and stability. The DDM85 lacks all kinds of clutches and needs power to stay put. Without power it is dead in the water. I consider this a show-stopper for all unmanned remote ventures. The DDM85 is direct drive, the ME II and all 10Micron mounts use belts for the reduction stage before the worm gear. The ME II needs PEC in order to work well, the 10Micron does not (encoders).

Pointing performance

The ME needs an external software in a PC in order to point accurately, as does the DDM85. The 10Micron mounts all have the pointing and tracking model in the mount so they point well without any external software.

Tracking performance

The DDM85 will track a target accurately for extended periods of time when you build a declination model in the Autoslew software. The 10Micron mounts deliver unguided performance with a standard sky model housed inside the mount (no PC needed). The ME II needs guiding...

Encoders

The DDM85 and the 10Micron mounts feature absolute encoders, the ME will be upgradable in the future. The latter is a concept that I simply do not believe in because of the extreme precision needed when mounting encoders. The DDM85 has higher resolution encoders than the 10Micron, but the latter has some very clever algorithms that compensates for this nicely (it is still more than 12 million ticks to a revolution, though).

Reliability

The ME II is a very reliable and predictable mount when run with PEC. The 10Micron mounts are equally mechanically reliable but need no PC in order to perform to spec. I know of two 10Micron mounts that have given the owners minor headaches. One was a faulty electronics component that threw the tracking off, one was a fabrication error of a belt.

The DDM85 has a few issues. According to direct information from a few owners, some mounts have been back to the factory a few times and some have been returned because they simply could not make them function. There have also been some issues with repeatability in homing the DDM85. The ASA direct drive mounts also needs a procedure, nowadays automated in Autoslew, that calibrates it to the motors.

Customer support

Bisque are known for their excellent support and ASA were known for their lack thereof (yes, bold statement and they have improved, but still). 10Micron is closer to Bisque but not quite up on the same level. They do, however, use Baader Planetarium as their European "main representative", a fact that raises the level of support some more.

The dreaded PC

The ME II needs a PC for pointing and sky modeling. The DDM85 needs a PC at all times as the motors are fine tuned and controlled by the PC. It is a dead piece of metal and other material without the PC. The 10Micron ones need no PC at all. You can even build the sky model with the handset and it will track unguided as is.

Show-stoppers

Since I intend to run all of my stuff unattended I set the standards high. The DDM85 is off because of total PC dependency and the lack of clutches. At a remote site, power may be an issue and I do not want a free-swinging mount when the power is down for a while. Just imaging what will happen if the PC takes a dive or the power is cut right after a slew is initiated. It would just go on until it hits something - expensive...

I do not want any homing procedures. No matter where the mount is pointing, it should be able to tell me that directly after power-on and do so reliably. If you loosened the clutches and moved it around while powered off it should still know where it is, to a tenth of an arc-second.

Alignment

ME II has a polar scope, DDM mounts, I think, don't need it. The 10Micron mounts don't need it either.

Don't get me wrong here, all three are excellent mounts and will perform very well. I do not work in the mount business so I have nothing to gain, but I do feel strongly the need to properly investigate mounts, in particular, before committing to such huge amounts of money. I did thorough research and arrived at 10Micron, a choice I have not regretted. It is a good and very reliable companion in my astro efforts.

I test-shot a one-hour single sub from my balcony pier with the GM2000HPS at 1000 mm focal length and got perfectly round stars:

So, whichever of these THREE mounts you go for, I do not think that you will be disappointed. It is, however, a large sum of cash to part from so you need to weigh all the facts according to your own view of the universe and your specific needs. Let us know how it goes!

All the best,

Per

My babies

GM2000HPS, divisable head version (Ultra Portable they call it...):

[jaspalchadha]

Very good feedback. I'll probably aim for the 10micon.

[ollypenrice]

Per and I probably know the same people when it comes to the difficulties associated with ASA so there's no need for me to repeat what he said, but I do agree with it.

The Paramount has a larger payload than the smallest 10 Micron but is not vastly more expensive so it fights back if your payload happens to lie between the two 10 Microns - as mine does, unfortunately!

Olly

[jaspalchadha]

I am drawn towards to 10micon 2000hps

At £9K

That's 1K cheaper than the me 2. Plus doesn't include the encoders

[perfrej]

Per and I probably know the same people when it comes to the difficulties associated with ASA so there's no need for me to repeat what he said, but I do agree with it.

The Paramount has a larger payload than the smallest 10 Micron but is not vastly more expensive so it fights back if your payload happens to lie between the two 10 Microns - as mine does, unfortunately!

Olly

Yo! Mr Guider

I hate guiding...

/per

p.s. There is always the GM4000HPS with 150 kg imaging load capacity 

For reference. GM4000 takes 150 kg, GM2000 50-60, GM1000 30 kg

[swag72]

You've already got an AZEQ6 mount? Have you reached the limits of that mount already?

[ollypenrice]

Yo! Mr Guider

I hate guiding...

/per

p.s. There is always the GM4000HPS with 150 kg imaging load capacity 

For reference. GM4000 takes 150 kg, GM2000 50-60, GM1000 30 kg

Oh, I'd quite like not to guide but it doesn't bother me. I'd rather guide than fight a war with a DDM. The trouble is that the GM1000 won't carry the double FSQ setup (probably) and the bigger one is more expensive than the Paramount. Quite honestly I'm drawn towards the EQ8 myself, since we have no plans to run a very long focal length on it. EQ8 plus 29 Meg full frame camera versus Paramount or 10 Micron on its own for similar outlay? Makes you think, no?

Olly

[andrew s]

I have a Paramount ME and you can image without guiding. It and the other Paramount's can track well using the supplied ProTrack option without auto-guiding. You don't need a polarscope to polar align it. I have used mine to put target stars on a spectroscope slit and take spectra without any auto-guiding or manual intervention beyond starting the control script.

Regards Andrew

[perfrej]

Andrew,

Thanks for the info. That's an external software, I take it, that runs in the PC. What kind of sub lengths do you get?

Olly,

Yes, the EQ8 is an interesting prospect. If you accept guiding anyway then it is a remarkable bargain. 29MP? You know where I stand on that subject...

/per

[perfrej]

Checked it out on the Bisque site. It uses the TPoint model to send guide corrections to the scope (1/3" per move) and claims 20 minute unguiding performance at FL 2500mm. Similar to ASA claims. Since it doesn't have any feedback from the mount motors it will not be able to produce any spectacular results. If the image presented on the site is to be representative of what can be expected - and I don't think it is - I am not impressed. My guess is that it can perform better than that but will not be very repeatable since it doesn't know where the mount actually is and the only reference is the last homing command.

It is, of course, much better than no augmentation at all, but it is not the way to go. Encoders is the way to go, mounted and calibrated at he factory.

/per

[andrew s]

Not quite right /per, What happens is you build a TPoint model which compensates for the mechanical issues of the mount and telescope. These include the major geometrical terms like polar alignment, non-perpendicular axles and scope related issues like flexure of the telescope tube.   This improves the all sky pointing which in my case is about 10-20 arc secs. This is used in the ProTrack module to make corrections to the mount dynamically to compensate for all the model terms. It is a feed-forward control and is open loop.

The ME and current MX and ME II mounts don't have encoders that close the loop on the axles but axis encoders can't close the loop of issues like tube flexure, polar miss alignment only the gear trains.

I have not used the other mounts so I can't comment on them. All I can say is that The Sky X with Camera, TPoint and ProTrack add-ons & Paramount makes for a very capable system.

I wrote my automation script in JavaScript and it runs directly from The Sky X. I did this as I need to do things image's don't need like offsetting the target star on to the slit. 

I have run up to 10 minutes without guiding but as I am not directly imaging I can't post an example to compare.  I have not yet tried to go longer although I have seem much longer examples on the SB web site.

Regards Andrew

[perfrej]

Yes, we're basically stating the same thing, but you have the correct wording

It's an open loop with no feedback but the mount's assumed position.

Autoslew an 10m have the addition of a closed loop with full feedback, in the case of 10m dual feedback as both the motor encoders and the axis encoders are used.

/p

[andrew s]

Not wishing to make a big issue of this but as I pointed out above motor and axis encoders notwithstanding your mount is still open loop to many other mechanical issues. In the end it is the performance of the whole system that counts not what technology is used to achieve it. I am sure from what you say your mount is very capable as is mine.

Sorry to split hairs on ProTrack but non Paramount users can use TPoint but ProTrack is only available on the Paramounts.

Regards Andrew

[perfrej]

Well, I don't mind a hearty discussion

It is closed loop for the motor and the axis. The flexure, orthogonality and polar alignment error are all modeled and compensated for (open loop but with reactive feedback, shall we call it half closed or half open?). There is a good (albeit somewhat commercial) piece written on it. http://10micron.de/informations/differences-between-mount-drives/?lang=en

I am totally aware of the fact that ProTrack can only be used with the Bisque mounts. My only concern is that there is no feedback as to what actually happened to the axis after the correction, all due to the lack of encoders.

The Bisque mounts are excellent products, no discussion there. In fact, I think that when they finally will release the encoder solution and have all the software fully available it will be in ASA and 10Micron territory when it comes to tracking and unguided operation. Bisque should be credited for stating that encoder additions are ONLY available as options installed at the factory. AP still thinks that an absolute encoder solution can be a field upgrade, a fact that tells me that they have not understood the technology involved nor taken the challenge seriously.

A disadvantage for Bisque will be the price of the encoders. They estimate $3000 per axis for the upgrade!

10Micron invested several years worth of time into the encoder solution and Bisque is doing the same thing. There is a reason for Bisque not yet having released the encoder solution: it is difficult and complicated. Again, I credit them for not rushing that upgrade - good call, and the end product will be so much better.

Technology is rushing forward. Both ASA and 10Micron represent leaps in mount technology and solutions. Bisque represents solid mechanical and market knowledge and will eventually get into the high tech stuff too (I'm talking encoders).

Are you planning on getting the encoder upgrade when it comes out?

All the best,

Per

[andrew s]

Simple answer is no. For two reasons' firstly it will not be available for my old ME and secondly it is not cost effective even if it were available. I find the mount is accurate enough for my needs and if I want to do longer exposures than I can open loop I will just close the loop and auto-quide. I can initiate this via the scripting quite simply.

I was a control engineer many years ago and the lesson from that was in the end however good the other control elements were closing the loop on the set point (star in this case) was the final step to perfection.

In the end you can apply as much technology as you like but if you can keep the star within the seeing disk you can do no better at any price or complexity.

Regards Andrew.

[perfrej]

That's food for thought

For me it's the obsession of technology and not needing to guide. My NEQ6 (guided, SKF bearings) tracks beautifully and is my second backup mount.

/per