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#26 coz

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Posted 23 March 2011 - 06:54 AM

Thanks, I'm going to check it out. It would be hard to beat AP's customer service and support which is a big factor with a major investment like this. Unfortunately I usually want to the latest technology. I'm still on the wait list for the AP mount so I have some time to decide!

#27 SL63 AMG

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Posted 26 March 2011 - 01:42 AM

I recently took delivery of a new ASA DDM60 Pro with an ASA N10 10" 900mm F/3.8 Astrograph with Wynne correctors for F/2.8, F3/6, and F/6.3.

I bought the Pro mount with all of the cabling through the mount, the astrograph, correctors, rings, flight cases, etc.

Since I live in a light polluted town in western Kentucky, I planned to travel with this system. It takes 3 large cases at nearly 100lbs each, plus a few small pelican cases for camera, correctors and miscellaneous gear. To fly with this system, is no small undertaking. A driving trip would be a snap with an SUV. It all fits in the back of my Mercedes GL-550 quite nicely.

I have had a bit of trouble getting my system up and running, mostly due to a controller issue with the OK3 focuser. The OK3 focuser has no manual control, so without a controller attached to a PC, there is no focusing of this system. There are no knobs. I am OK with that, as long as the controller works. Mine have been returned to ASA and I am currently using older working controller compliments of OPT.

Setting up this system is no trivial task, at least not without a lot of guidance. Now, let me state, I am not experienced in imaging. I have one year of experience tinkering with my CPC-1100 on a wedge with trying to autoguide a long focal length mirror shifting SCT and a small refractor. That in and of itself is not a simple task, although people are doing it.

So, now that I have the focuser working quite well, with a lightbuckets driver that automatically homes the focuser and positions it to last known focus upon start up, I am working on a number of other "setup" related issues that, for me, have a steep learning curve.

Without any step by step clear documentation on tuning the mount, I was left with a bit of guessing until one of the engineers from the factory connected to my laptop remotely and showed me the process. It is quite simple, but one must understand that ANY changes to the weight and balance of the system will require re-tuning of the mount. Once you understand what to do, this is a trivial task. I know have mine setup as I will image regularly so it is a set and forget procedure. If I decide to mount my refractor as in my photos, I have the PID values written down so I can quickly tune for that setup.

To get a good polar alignment, after leveling the mount (no level bubble) using a small level, I use the software (Autoslew) to turn on the laser and try to point the laser as close to the known celestial pole as possible. Within one degree is good enough as the software will figure out your offset and guide you in adjusting it later.

After polar aligning the mount with the laser, you must now shut down the software, point the OTA at the Zenith (slightly south) and the counter weight shaft to the eastern horizon level with the ground (slightly elevated), then start Autoslew and let it perform a home find. My understanding is that from this position, it is finding the physical stop points of the servos and noting the positions of the encoders.

Once the home find is completed, you can start a pointing file in order to polar align the mount. ASA claims four stars are sufficient for this purpose, but I have found taking the time to do 6-8 provides better results.

For this process, I am about to endeavor into the world of sequence and plate solving because making pointing files plain sucks and it is time consuming, at least for me. Basically, here is the process.

First, you need these two items:

A) Finder Scope. I recommend mounting a good finder scope on your OTA and align it. I installed a StellarVue F50M2 on my OTA rings and it has cut my "pointing file" time by 40%.

B) Joystick. I recommend a joystick or game pad connected to Autoslew. This has also cut my pointing file time dramatically.


1) Connect TheSKyX to Autoslew via POTH.

2) From TheSkyX, select a bright star on the same side of the meridian that you wish to image and slew to it.

3) Use the joystick and drive the mount to position the selected star in the crosshairs of the finder scope.

4) Use MaximDL to take continuous photos of the target, then use Autoslew or the Joystick (Autoslew is more accurate here) to position the star precisely in the crosshairs of the image in MaximDL. This is where automating with Sequence and plate solving would save a lot of time. I am about to get to this myself, so I have not experience yet.

5) Once the star is centered, confirm it in Autoslew with a single click.

6) Go back to TheSkyX and find another star and slew to it and repeat the process until you have 6-8 stars in your pointing file. Make sure you final star is one at or near the intersection of the meridian and the celestial equator. Once centered and confirmed, synch to this star in TheSkyX.

7) Close the pointing file and then tell Autoslew to calculate the real positions from the actual positions. IT takes a few seconds and it is completed. From here, pointing is very accurate, but tracking is not ready.

8) Select the Polar Alignment function and let Autoslew calculate your polar offset. The click Move Star and Autoslew will move to the polar offset in exactly the opposite direction.

9) Adjust the mount with the four screws and center the star manually. Once you have that star back in the crosshairs of your image in MaximDL, you are done with polar alignment.

10) Now you must make a new pointing file. I recommend 10-15 stars as Autoslew not only uses the pointing file for accurate Go To function, but also to make small adjustments to the tracking in real time (100x per second).

From here, I was able to shoot 5 minute unguided subs. I do have some star elongation, but I am told it is due to poor collimation of my very fast Newtonian Astrograph. I have ordered the cats eye collimation tools which should be here next week. We shall see.

For now, you can view my system and some quick test photos on my website. I will be happy to answer any questions you may have to the best of my limited ability.

Keep in mind, these images are mostly Ha (during last week's full moon) and they are uncalibrated, single images (no stacks) and no processing other than a simple screen stretch before saving as a tiff file.

I am only sharing them to show you what may be possible, but I am certainly not there yet.

Space Igloo

This process has taken me several hours each night. Perhaps it will get faster when I have more experience, but right now, it is slow tedious work. I do believe, however, that in the end, I am going to be a very happy camper.

Dave


#28 ASTERON

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Posted 26 March 2011 - 03:56 AM

a friend of mine has the ASA DDM60 Pro and he has been doing 15 minutes unguided subs that look absolutely smashing.
he claims that there is a very intensive and steep learning curve with this mount because it is using a principle of operation which is very different than conventional helical gear based mounts ( the ASA is a direct drive mount with the motors directly driving the mount shafts.
Dave described the process nicely.
I think for anyone working from a fixed observatory it will be a fantastic mount - you will sweat in the beginning but once you're set you could probably push the ungiuded subs to 30 minutes easily.
for portable use this will be more complicated because you will have to do polar aline and build new pointing files each time you set up.
He also claims that ASA were very helpfull in assisting him (even online) with mastering the setup technique.

#29 coz

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Posted 26 March 2011 - 07:32 AM

thanks for the information. I'm using the mount in the field and so I think Im going to pass on the ASA due to this setup. If it was going in a permanent location I would definitely reconsider. thanks!

#30 SL63 AMG

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Posted 26 March 2011 - 10:13 AM

As I stated, I bought mine for field work, complete with flight cases. I have been working with Eric at OPT and one of his buddy's who has the DDM60. They both told me this setup time can be brought down to within an hour, especially once sequence is used to build the pointing model.

The physical setup and tear down is much quicker than my CPC-1100. My portable table is less cluttered.

For observatory use, I would purchase the DDM85 or DDM160.

I am confident that I will be able to use this in the field with reasonable setup time. I'll keep you guys posted and let you know when I am ready to attend my first star party!

Dave

#31 Tal Fibish

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Posted 28 March 2011 - 03:54 PM

Hi guys,
I own ASA DDM60 Pro mount for almost 3 months.
I looked around the market for a new monut for almost 2 years.(I had Synta NEQ6 mount). because of my Meade 10" LX-200 , I needed a high accuracy mount.

After I checked every mount on the market , I bought ASA mount because it made no sense to pay 10000$ for a mount that still have the same old problems (PEC)when I can get much more for almost the same price. and NO GUIDING NEEDED !
I think it was the best puchase I ever did for my astrophotography hobby.

The mount in one word is : DIFFERENT ! (in the good way)
forget everything you know about guiding & PEC ... throw it a way ! it's not needed anymore.
becuase of the electromagnetic motors there is no PEC so if you set the mount right ,no guiding is necessary. which save you a lot of precious imaging time.

I'm not impressed easily , but to do 15-25 min frame unguided in 2500mm focal length and 30-40 min unguided frame in short focal length, it's something I never imagined to do. (I also have William Optics FLT98)

at first it takes a while to understand the new software and set everything up at the field but after a few times it gets much easier. now it takes me a about 30-40 min to set everything up. but when you done - you done ! .
I'm stopping the imaging only when I need to refocus the camera.

"A picture is worth a thousand words"
Take a look here :
http://www.pbase.com...957809/original

all frames are 15 min Unguided . (please ignore the stars around the edges of the image , it's cause by coma)

Tal.

#32 Tal Fibish

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Posted 28 March 2011 - 04:12 PM

Hi Dave,
what don't you use Sequence ? it will do the polar alignment pointing files and the "real" poiting file much much quicker using plate solving. it takes only a few minutes.

also if you use the mount at the field you don't need a pointing file at all (after Polar alignment of course).
just use SEQUENCE "Local Tracking" .

Contact me of you want some tips how to set the mount up quicker ... :)

Tal.
faibisht@012.net.il

#33 GeorgeFC

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Posted 29 March 2011 - 04:17 AM

I have a DDM60 set up in an observatory so I cannot comment on how easy it is to use in the field. As others have said, there is a steep learning curve, and it took me the best part of a year to get really familiar with the mount. My previous mount was a non-GOTO EQ6 so I had a lot to learn.
I have also been building the observatory and refurbishing my home made scopes, and the UK weather has not provided many opportunities for imaging so under better circumstances the 'apprenticeship' would be shorter.
I am now at the stage where I can open the observatory, do a 'homefind', slew to the target with an accuracy of a few arcseconds and start imaging within 5-10 minutes.
Because my scopes are homemade and lack the rigidity of carbon fibre, I have only pushed the unguided capabilities to about 5 minutes. I use a Lodestar in an off-axis guider, and use pulse guiding to send very small corrections to the mount. On a good seeing night the guiding stays at <0.3 pixels at 1500mm focal length which is probably the limit of the seeing.
Cartes du Ciel (free!) drives the planetarium side.
Feel free to visit my website where I have documented some of my ramblings.
http://geoastro.comeze.com/

George

#34 Starhawk

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Posted 29 March 2011 - 08:36 AM

Look at the power draw for these. The ASA mounts do not have the field portability of even GOTO mounts like the Mach1. These require a full PC to support them. Also keep in mind they need a 30 minute setup routine every time they come on.

What they are doing is using technology developed for large CNC milling machines, where encoders directly on the axes and movement is controlled directly to that reference. So, for example, if it had a worm drive, there still would be no periodic error because the encoder on the axis would be the reference for movement. The catch here is the encoders are expensive- more so than the ones on the motors in conventional GOTO mounts because they have to be much higher resolution; GOTO encoders on a 288 tooth worm have 288 times the resolution they would if mounted directly on the axis.

The direct drive is a separate technology. Again, it comes from industrial machinery, and is the expensive, but speedy way to move things around. I haven't seen a large observatory using this. Even the LBT uses gears. It would drive a lot of expense to have a custom drive motor made, and I'd be concerned over having something producing such large and changing current draw on the same circuit I was powering a camera with.

As has been pointed out, this is blind to what the atmosphere is doing.

For me, the long story short is direct drive with axis encoders has produced a very capable system, but one with limited practicality for anything but a permanent observatory. Given a fully autonomous autoguider is now $300, and can drive a battery powered mount, it isn't like there aren't fully capable alternatives.

-Rich

-Rich

#35 GeorgeFC

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Posted 29 March 2011 - 10:17 AM

Putting encoders on a worm-drive mount is indeed an option.
However, problems with backlash could still remain and there would be a 'dead time' as the backlash is taken up.
This does not happen with direct drive.

#36 Tal Fibish

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Posted 29 March 2011 - 10:35 AM

Hi Rich,
Yes it takes longer to set the mount up in the field , but you forget a very important thing.
when you done setting the mount up ,you don't need to waste any more time on guiding errors or any other common problem , how many times you wasted a few hours in the field to try fix a guiding problem ? I know that I did , that's why I swiched to that mount.

Tal.

#37 Starhawk

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Posted 29 March 2011 - 05:53 PM

Tal, I suppose I'm just having trouble seeing the benefit between an assured slow setup and a mount which is quick to use once you get it dialed in.

I think everyone has nights where they fight with the scope, but generally that gets worked through. It seems the ASA never gets to that point.

-Rich

#38 Tal Fibish

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Posted 29 March 2011 - 06:37 PM

Rich,
You maybe right , but I prefer to spend even an hour to set up and tune the mount and be worry free all night.

but also you need to see all the other benefits with this mount , the high accuracy motors not only allows you unguided imaging but also when you imaging with high accuracy mount there are less "motion blur effect" that caused by guiding corrections . which will result much sharper data and perhaps even higher SNR.

ASA mount is new , it will probably take a while , but I beileve that eventually ASA will improve the software and will develop new and faster ways to set up the mount.
Before "Sequence" software was created the process was much longer , now its relativly quick.

Tal.

#39 BPO

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Posted 30 March 2011 - 01:30 AM

Hi Starhawk.

With regard to the power consumption of ASA's DDM-85 direct drive mounts, as I understand things they draw no more than similar observatory class mounts such as the Paramount ME from Software Bisque, while the portable DDM-60 consumes significantly less.

"I think everyone has nights where they fight with the scope, but generally that gets worked through. It seems the ASA never gets to that point."

This is a puzzling claim: the DDM users over on the ASA Yahoo! tech group appear to be having few major problems, judging by the amazing images they are often posting! :)

Also, while there were some questions and hiccups with earlier control software versions, the latest appear to have eliminated those.

#40 GeorgeFC

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Posted 30 March 2011 - 03:19 AM

Keep in mind that my scope is a home-made 10" Newtonian, but this image shows that my days of struggling with guiding are over:

Posted Image

#41 Geo.

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Posted 30 March 2011 - 11:27 AM

Think S&T did a short write up on this mount last year. With the Paramount @ $12.5K I'm not sure what the 55 hundred gets you.

#42 Starhawk

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Posted 30 March 2011 - 11:32 AM

I spend a grand total of 15 minutes getting an accurate alignment on NexStar controlled mounts, and I can start shooting photos in the early evening, and I'll use that alignment until the approaching dawn ends my photography session. To spend a couple of hoes building pointing files frankly sounds absurd. I've never needed hours to get an autoguider running, so again, it just doesn't seem reasonable to lose your best observing hours each night you use a mount to setup. And that's what I am getting at: early on, there is a learning curve, but there us an expectation of it going away. Having to build new pointing files every time is a lot of work.

And for power consumption, the alternatives really need to include mounts without a sepatatate computer drive which are autoguidable. To make the comparison alternative only the Paramount isn't a realistic trade.

-Rich






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