Monday, September 24, 2012

Broken mount :-(

After I got more and more "No Response 16" and "No Response 17" errors, my mount finally broke completely. In dec, it slews immediately at full speed (i.e. no gradual acceleration or slow down). And as a result, it completely over slews. It's impossible to align. Send a note to Celestron support, but didn't hear anything yet (will call them tomorrow).

So, I do all kinds of other stuff. Today, I played with the flatfield panel for taking flats. That will be SO much easier to take flats (even when I change my mind in the middle of the night and change the setup). And I don't have to play with exposure times anymore, but they are fixed now:

 ISO 400  1600  5000 
2x Barlow  1/3 1/13  1/50 
T-adapter   1/20  1/80  1/250
T-adapter + Focal Reducer  1/30 1/125   1/400
T-adapter + LPR Filter  1/13 1/50  1/160 
T-adapter + Focal Reducer + LPR Filter  1/20  1/80  1/250

Saturday, September 8, 2012

And now everything together

So, I finally put everything together:
  • balanced my scope
  • used the skyglow filter
  • used PHD (I can now do 4 min exposure times and have less then 10% failures!)
  • alignment, calibration and polar alignment with the reticle lens (though I still haven't tried/done the drift polar alignment)
  • finally cleaned out scope and camera
And the result is pretty good:

I also tried longer exposures with M57, they are better then the ones I had before, but not as good:

What's not so good:
  • the dew shield does not warm up anymore
  • I am still getting a number of "No Response 16/17" error messages. Checked the Celestron website and found some tips what to try. I'll do that when I come back from my trip.
To take photos without the scope, I bought an ultra-wide angle zoom. I'll take that with me on my trip (and also my tripod). I hope to take some wide angle shops when I'm in Zuerich (I hope that I can go on top of my hotel at night!)

And I was fed up with the process of taking flats at dusk or dawn and ordered an EL panel that will allow me to take flats anytime I want.

Tuesday, September 4, 2012

Got PHD autoguiding to work!!!

After many, many attempts, I finally got autoguiding to work. There were too many mistakes to mention here (chose a hot spot as a guiding start, calibration step size too small...) But finally it worked.

I tried it then by having a star (Altair) smack in the middle of the reticule - and it stayed there! Tomorrow I'll try to take pictures of M57 with eyepiece projection!

Not so good news: I had lots and lots of mount issues ("No Response 16") - will have to mail Celestron support about it.


Tonight, I wanted to take pictures of M57 - this time without the focal reducer. Setup was quick! I then tried my luck (again) with PHD, but this time, during calibration, the scope did not move at all. I didn't bother to try to figure out what it was, but started taking pictures. I wanted to compare slower (30 sed) exposure time with longer (2 min),

Here is the result from 30 sec:

And here is the result from 2 min:

This is after super simple Background offset and DDP in Nebulosity. I'm sure that I could correct the background in the second picture. But there isn't more detail in the second picture!

For 30sec, I had to throw away 10 (20%) of all pictures. For 2 min, it was much higher: almost 50%!! Almost all "bad" pictures were "shaky" - I wonder where this still comes from. If the scope wouldn't be able to track properly, all pictures would be bad. But that some are bad and others aren't makes me believe that there is something else.

So, it seems as if this nebula is bright enough that it can be captured with just 30 seconds very well. Furthermore, it's sharper with the 30 second exposures. Maybe I should try it to do this with eyepiece projection (and maybe higher ISO to keep exposure times short).

Monday, September 3, 2012

M31 with the skyglow filter

So, I put the starfinder under the guidescope bracket. It's pretty snug aligned to the guidescope, i.e. it won't wiggle too much. That will make alignment and calibration SO much easier. I should get some double-sided scotch tape to fix it further.

Now, I had to start the night with a whole lot of adjustment:
  1. Rough adjustment of the starfinder (not easy if the scope is not tracking yet)
  2. Alignment, calibration and polar alignment
  3. With tracking, adjustment of the starfinder and focusing and adjustment of the guidescope
  4. And now another round of alignment, calibration and polar alignment - this last run-through was a breeze!
Then I tried to get PHD working. I could easily get the starshooter camera to focus (haleluja for perfocal rings!) But when it calibrated, it could not calibrated the dec axis. And when I tried guiding, it went quickly out of center. I decided to rather take some photos instead of trying to get PHD to work.

First, I wanted to take photos of M57. But it came out very small in the photo - I should try that without the focal reducer. But I didn't want to take the whole camera off and such.

I tried to take longer exposures from M31: 4 minutes. The photos looked pretty good, but of course very saturated. So, I tried out the light pollution filter. The photos came out very blue, but not too saturated.
I set the scope to take pictures the entire night. When M31 was behind the gigantic redwood tree, I started to take darks - and then set the alarm to 1am to get up and setup the scope again for lights.

In the morning, it was clear, so I could take flats and dark flats. But it turned out that the scope stopped tracking again. When I read more about it, I found out that CG-5 scopes stop when an object crossed the meridian. Obviously, they can't track further. I was wondering if there is some option to automatically flip around, but that's not possible :-(

But at least I had 40+ pictures - each 4 minutes long.

I first stacked with DSS. Nebulosity could not deal with the blue hue. So, I tried to do some basic post-processing in Photoshop instead:

Not too bad. You can see some details of the spiral arm - but the bright center is overpowering. I need to figure out how to combine two images to get this better.

Sunday, September 2, 2012


I tried M27 again. And...

... I think this is a really neat picture:

And even blown up, it still looks good:

I even did some basic post processing in Nebulosity myself...

A couple of observations tonight:
  1. Aligning / Calibrating is just WAY easier with the starfinder then a finderscope. I ended up taping(!!) the starfinder to the telescope to get it done. I need to find a way to get both onto the telescope.
  2. The stripes that I saw yesterday, I could also see today. I think the scope has some issues when it has to go through the zenith. When I made the telescope go to M27 again, it slewed all the way around.
  3. I could easily do 2 min exposure time!
  4. I wanted to use the starfinder for guiding, but suddenly the computer could not work with it anymore (although it worked during the day).

Saturday, September 1, 2012

Polar Alignment with the new mount

Took photos of M31 with the new mount. I still can't use exposure times >30 seconds :-(

The photos themselves were decent - pretty much the same quality I had before with the old mount.

And what's really annoying, I get quite a lot of "No response 17" error messages (at which point I have to swich the mount off and start all over again with alignment :-( I searched around and it seems to be a common problem with the Nexstar mounts. If it doesn't get better, then I might have to send the mount back.

I then tried to take photos of M27. It's much higher in the sky. Here I couldn't even take >10 seconds exposure. The mount slews exactly to the objects, so it should be well calibrated. Maybe I have to improve the polar alignment. And at some point, the scope stopped tracking completely. Couldn't use these photos at all.

Took the scope out during the day to work more on polar alignment during the day.
  1. Did a Sun alignment
  2. Polar alignment
  3. Turned scope off, did another sun alignment
  4. Another Polar alignment
    You would think that at this point, there is no correction necessary as I just did a polar alignment. But it was still a little bit out of alignment
  5. Again, turned scope off, did another sun alignment.
  6. Another polar alignment
    And though it was less then before, it still wasn't fully polar aligned.
Not sure if I'm doing something wrong. But all instructions that I found said that one star alignment and one polar alignment should be enough - not that this is such an iterative process.

I then put the tele-extender on the scope to try out eyepiece photography on the sun. The resulting photo was OK:

I'll leave the scope outside and will take more photos tonight (if it doesn't get cloudy again).