Thursday, February 14, 2013

Setting up the filter wheel and the off-axis guider

I finally received my filter wheel from Starlight Xpress!!! So, I could set that up and also finally use the off-axis guider from Starlight Xpress.

First, I reconfigured the scope: removed the 4 spacers (for correct backfocus) and replaced it with the filter wheel / OAG. And now, I can use the reticle eyepiece in the guidescope. And I had to do a bunch of recabling (and need a shorter USB cable for the filter wheel).

Then, I tested the filter wheel with the test software from Starlight Xpress - works!

Next, I connected the filter wheel to TheSkyX. Assigned names to the 7 filters. But then I couldn't control the filter wheel from the camera plug-in. It just didn't move at all. I checked the Bisque forums and a couple of folks mentioned issues with the Starlight Xpress filter wheel when they used a USB hub. So, I connected the filter wheel directly to the laptop - but same result. The weird thing is, when I connect TheSkyX to the filter wheel and use the Starlight Xpress program to move the filter wheel, TheSkyX shows status "Moving". I.e. there is some connectivity to the filter wheel.

Then I wanted to figure out the difference in focus. I used the Bahtinov mask for this and subframed stars in to get a very accurate focus. The 4 Baader filter (LRGB) have the same focus, while the Ha filter (from Orion) and the OIII and SII filter (from Astronomik) have an offset of +36. I could enter the offset into the Ascom driver, but not sure if and how that would be used from TheSkyX. It would certainly be helpful if TheSkyX automatically adjusts the focus when changing filters.

As the final step, I needed to focus the lodestar. But all lodestar images have a very strong glare in TheSkyX:

I don't see that effect in PHD or the lodestar program (from Starlight Xpress). Though in TheSkyX I see WAY more stars then in the other 2 programs. I asked on the Bisque forum about that.

And throughout the entire night, I had several connection problems. At some point the cables that run down the mount (USB, power) got loose when the mount slewed into an extreme position (I extend those cables a little bit). The serial ports needed some wiggling before they wanted to connect. And I had a power outage again - I can't seem to figure out where this comes from (I already replaced the 12V adapter and also the splitter).


I received a couple of answers:

Apparently, the image from the OAG is normal... I can try to use one of the stars - although there isn't much of a contrast. I could also try to take flats (and maybe darks and bias) to reduce the image properly. But wouldn't I need to take new flats every time I change the OAG (move it in or out - turn it).

Interestingly: when I started autoguiding with an image like the above, I got this picture in the subframe:
It seems as if subframing helps with the vignetting. So, that might work!

With this, I tried autoguiding in TheSkyX. Now, with the OAG, the movement should be much more sensitive. In x-direction, the default of 10seconds for the relay worked. But in y-direction I had to go higher then 100 seconds for the relay. In the +y direction it worked with much smaller values. But in the -y direction I needed the high value. I wonder if this is because of backlash in the mount. And if yes, if it will improve once I hypertune my mount (maybe this weekend?)
I started guiding with TheSkyX and could finally get it to work. But I had an image shift - like I had when I tried to guide with the guidescope. But the shift was very slow, good enough to try some imaging.

With regards to the filter wheel, I was (of course) asked to update to the latest version of TheSkyX - done.
I was also told, that TheSkyX only moves the filter wheel when I am taking an image (i.e. not when I just select a different filter in the drop down).
And finally, that I need the "driver in the ASCOM category that's installed along with the application."
I tried this, and the filter wheel indeed turns before taking an image. But after a few images, it timed out with the 209 error (as described in the Bisque forum).
I could not figure out what was meant with the ASCOM driver, will have to reply to the Bisque forum.