Telescope Reviews: ASA mount

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