Saturday, December 28, 2013

Weird, wild rotating of the Mach1 mount ...

Last night, when I started my imaging session, I noticed that my handcontroller didn't work. I pressed various buttons (trying to indicate my location), but nothing worked. Checked if the handcontroller plug was firmly in the control box. I finally decided to leave it alone as I'm using plate solving anyway for slewing to my targets. So, I synced the scope from TheSkyX to a star and then started my imaging session.

At some point later (more then an hour) I could hear my mount. When I checked it, it was spinning around the DEC axis. It would stop for a short moment at the north pole and then do another round. Luckily the scope was in a position where it didn't hit the mount!

I powered down the scope immediately. Started it back up. I then tried to use the handcontrol again. And noticed that if I pressed buttons often/hard enough at some point they would work. So, I did that and then continued my imaging session. But soon after the same spinning happened again.

I suspect that the hand controller is faulty. Tonight I'll use the mount with the handcontroller disconnected and see what happened. I also posted on the ap-gto mailing list - maybe anyone there has an idea.


I followed up directly with Astro-Physics support and they also suspected that this was the motor itself. But because I'm mostly imaging, they gave me some useful advice:

  • Set AutoConnect=EXT (meaning, the external controller aka my computer has priority over the keypad)
  • Don't use Park 1, use park 2, 3 or 4 (I did use park 1, now I'm using park 3 which I like most during the day anyway)
  • Be sure that the AP V2 driver is set to convert all Sync commands to ReCal
  • Be sure to NEVER GoTo with the Keypad and ReCal (or Sync) with the computer or vice versa

I did all that and since then didn't encounter any issues.


A friend of mine gave me his AP keypad and I tried it out. And it didn't create any issues (tried several times). So, there is clearly something wrong with my keypad - not sure if it is the cause for the wild slewing.

Checking focuser slip

There were many reports around that the focuser that comes with Takahashi scopes isn't great and slips. I asked Richard Crisp how to measure it. He recommended to put the scope in focus, point the scope up and then move the focuser all the way out and back to the focus position and check if the scope is still in focus.
For this, I could use the Bahtinov mask and Bhatinov Grabber to measure exact focus. Luckily Capella was almost in the Zenith which made a clear Bahtinov pattern.
Here are the results (I moved the focuser several times to check if there would be small slippage over time):


Looks as if there isn't any noticeable slippage. Good!

Friday, December 27, 2013

Temperature Compensation

I noticed that the TOA scope shrinks quite a lot during the night when it gets colder. When I focus my scope first thing in the evening, it has to move almost 100 steps(!!) to regain focus (the last position was the focus point at the end of the previous night).

So, I used the TEMPer device to measure temperature and then the Bahtinov grabber do determine exactly the focus point:
1. Evening - 11.98 degrees - 29296
2. 1am - 6.91 degrees - 29224

That means I have to adjust 14 steps for each degree!

I entered this in SGPro. Next night, I checked but it didn't look as if SGPro adjusts the focuser (unless I run autofocus again). I checked in the log file and found a lot of lines like this:

[12/27/2013 4:34:31 AM] [DEBUG] [Sequence Thread] Temperature compensation: Adjusting for 0.0 degrees (end: 100.0; end: 100.0; coefficient: 14) for 0.0 steps...

Seems as if SGPro is not using the TEMPer device for compensation but the built-in Robofocus temperature (which always returns 100 degrees!) I asked on the mainsequencesoftware mailing list and was told that this wasn't implemented so far, but that the code is ready and will be in one of the next updates!


Checked the fix, but it seems as if the 100 degrees still come in from somewhere. Waiting for the next fix.


Release 2.3.1 seemed to address this! Worked perfectly the first night. But next night, the temperature was shown as NA. After some trial and error, I found out that I first have to disable this setting (Tools->Options->Other Equipment Options->Use a TEMPerHUM device) and then re-enable it. Then the temperature would be read properly from the TEMPerHUM device.

Thursday, December 26, 2013

Trying to use "Plate Solve and Blind Sync" in SGPro

I found out about the "Plate Solve and Blind Sync" functionality in SGPro. Instead of pointing the scope to a particular star, then centering it and syncing on that star, I could just point the scope somewhere in the sky, SGPro will do a plate solve and use the coordinates for the telescope sync.

Tried it out right away. And it worked "almost". I could see that the sync told the scope the correct direction (I could see in TheSkyX that the scope pointed into the right direction). But when I then tried to slew to a different location, the mount would run the telescope into the pier...

Asked on the mainsequencesoftware mailing list, but couldn't get a good answer :-(

Well, not the end of the world - but it would have been nice to safe an additional 10 minutes of setup time.

I got some more ideas how to make this work!
When my Mach1 mount started to slew erradically, I posted to the ap-gto mailing list. And from that discussion came several ideas how to make this work. Will try this when I'm back home next week!

Tuesday, December 24, 2013

New Scope #4 - Robofocus

I finally received the Robofocus stepper motor back (great x-mas present! :-) and could connect the Robofocus. With the bracket for the TOA 130 scope it was quite easy:

Connected it - worked immediately.

I then had to reconfigure the Robofocus module: change the step size, reverse direction (so that "out" means "out"!) But for some reasons, I could not connect the Robofocus control program anymore. I always got an error that the serial device is already in use. I remembered that I didn't use the control program for quite some time - maybe it was the new USB-Serial converter? I tried one of the cheaper ones (which doesn't keep its serial port) ... and it worked right away. Well, I only needed it to configure the Robofocuser and then could switch back to the newer adapter.

I set the step size to 1 (now the entire range of the focuser is ~5000 steps!), reversed the direction. And was done.

Same night, I configured the auto focus routine of SGPro. I used step size 10 and 15 data points. And it worked beautifully. I also finally understand why it's called a "V-curve" (with the EDGE scope it barely resembled one):

Saturday, December 14, 2013

New Scope #3 - First imaging experience

I am still waiting for the FLI camera and filter wheel, so I am using the H694 from Starlight Xpress for now. I had to get an extra connector from preciseparts from it :-( They aren't cheap, but it so worth it - very stable and robust!

First, I had to focus the scope. Without the Robofocus I had to focus manually. And I could even use my old Bahtinov mask - I bought it for my 6" SCT. And it fits quite well on the TOA 130.

Next, I wanted to adjust the red dot finder. I do remember that this was a major pain in the a... But with SGPro, I could use it's center function to center the scope on a bright star (Deneb) and then adjust the red dot finder until it was over Deneb. Wow - that was easy!

Then I wanted to do some basic curvature analysis. After all, that was one of the main reasons to switch from an SCT to a refractor. Took some random images and analyzed them with CCDInspector:

Not too bad! The remaining tilt could be with the imaging train. I'll investigate this more when I get my FLI camera.

Next on my list was to calibrate SGPro to take flats with my flip-flat. Took me a while to figure that out. But now I have all my filters calibrated. But the flats look like this:

Yikes! Seems like I got a lot of dust into the imaging train when I assembled it. Will fix that with the new camera too.

At some point when the scope pointed almost straight up, guiding became VERY shaky. Pretty much unusable. When I checked the scope, I noticed that the filter wheel was hitting the Mach1 keypad - which was dangling loosely. See these image that I took the next day:

Seems like I will have to move all the cables and everything to the front or back to the scope. This is certainly a problem that I didn't have with the shorter EDGE scope before.

Finally, I took some images just to see how they look like:

This is a simple Luminance image (10 subs a 10 minutes) of M31. Only stacked no processing whatsoever. Very impressed with the amount of detail that I can see here. Can't wait to take some real images!!!