Dithering preperation

[Pompey Monkey]

13 hours ago, ianpwilliams said:

Well that was a complete disaster. Whenever I tried to use GoTo++ in PointCraft I kept getting errors, including runtime errors, timeouts, and requests to check the ASPS settings. And when GoTo++ did "work" it was taking far too long  eg 10+ minutes just to do 3 of 5 steps, so I stopped it. And I got myself confused again in PointCraft, trying all the various buttons like Auto, Solve, Blind etc.

 

Also I could clearly see that the scope was pointing too far to the right whenever I slewed to a target using GoTo, despite the fact that I believe I did a reasonable polar alignment. Focusing was fine, as was guiding, and dithering seemed to be fine too, APT automatically going into dither mode. It was just the slewing that was the issue. 

 

Anyone got any tips on how I can avoid this problem next time? Maybe I should have just polar aligned again or something.

Oh dear.

Sometimes APT can get it's knickers in a twist, especially if you don't let it complete each task. In the past I found that parking the scope to the home position (with EQMOD), shutting down PHD and APT gracefully (i.e. disconnect the cameras and mount with the buttons) and then doing a PC reboot often helped.

Pointcraft in particular will throw a wobbly if there is still an instance of ASPS running when it tries to call it again...

Now I know a bit more about what I'm doing, I seem to make les mistaks  and the whole set-up is more stable.

[ianpwilliams]

Yes, maybe disconnecting and restarting APT and PHD2 might have helped. I can't reboot the laptop though because I would be there all night waiting for it to reboot!

 

And I did find that PointCraft was opening more and more Windows as time went on. So next time I'll close those windows where possible.

 

It's  clear skies again so I'm sure I'll get back out there. I just wish I had a better idea of how to fix things when they go wrong, just in case it happens again.

 

when you use GoTo++ in PointCraft how long is it usually supposed to take? Someones I was finding that it could take 5 or 10 mins just to do one step out of the five, which surely can't be right.

 

 

[ianpwilliams]

Yes, maybe disconnecting and restarting APT and PHD2 might have helped. I can't reboot the laptop though because I would be there all night waiting for it to reboot!

 

And I did find that PointCraft was opening more and more Windows as time went on. So next time I'll close those windows where possible.

 

It's  clear skies again so I'm sure I'll get back out there. I just wish I had a better idea of how to fix things when they go wrong, just in case it happens again.

 

when you use GoTo++ in PointCraft how long is it usually supposed to take? Someones I was finding that it could take 5 or 10 mins just to do one step out of the five, which surely can't be right.

 

 

[ianpwilliams]

Now that I think about it, there were one or two occasions where APT disconnected from the mount and I had to reconnect, so no doubt that would have screwed up the GoTo. I'm not sure what caused it. I used my newer Tracer battery for the first time but the mount didn't lose power. Maybe I should go back to the old battery.

[AstroJOE]

5 hours ago, ianpwilliams said:

Now that I think about it, there were one or two occasions where APT disconnected from the mount and I had to reconnect, so no doubt that would have screwed up the GoTo. I'm not sure what caused it. I used my newer Tracer battery for the first time but the mount didn't lose power. Maybe I should go back to the old battery.

I experienced a similar issue the other night when guiding with phd2 and using APT to capture, with dithering enabled. A couple of times when I stopped the APT capture (because a big cloud rolled over) I found that the Mount stopped tracking altogether and the stars started flying across the screen in live view. I had to turn the mount off (in hibernate) and then turn it back on to re-engage the goto and tracking controls so I could continue my imaging and guiding run. 

Is this the same thing and if so, is it avoidable? 

[ianpwilliams]

I did wonder if it might be connected to the dithering. This was my second session dithering, and APT defaults to dithering being on. So I wonder if that had anything to do with it. It was just really odd that I would be messing around with PointCraft stuff, and then I'd notice that the mount button would say "Connect" instead of "Disconnect".

[PhotoGav]

Mmm, I have had similar disconnecting issues with APT and mount or cameras in the past too. It doesn't appear to have any particular trigger and I have a feeling that it is more to do with USB issues and APT not being able to recover well from disconnects. What USB connections are you using? Even that is a bit of a futile question...

My most irritating experiences of this phenomenon is when shooting flats during the day on my dining room table. I have very little connected up, in fact just my CCD to the laptop. Quite often I hear the ding dong on the PC that warns that something has disconnected. That has to be the camera as it is the only thing connected. There is no reason why it disconnects, it just does and it seems to make no difference which USB port I plug it into on the laptop. Anyway, at that point APT has a complete fit and crashes. I have had to unplug the power cable from the CCD and restart the laptop to get things back up and running, which I hate doing as the camera is at -20°C and there is a risk of thermal shock on the chip when pulling the plug. So far it seems to have survived a few of these incidents. The worst thing is that when I finally get APT up and running again, it has lost all its settings and I have to reconfigure everything. Very irritating!

Interestingly, I have started to use SGP now and while shooting flats two days ago, the camera disconnected, but SGP dealt with the episode far more efficiently and I just had to reconnect to the camera in the software and everything was fine immediately.

So, my conclusion is that this is all down to a weird sporadic USB disconnection issue that is then poorly handled by APT. I have no idea what the solution is. One for APT author, Ivo, I guess.

[ianpwilliams]

I connect to my mount using one of those ASCOM cables from FLO, which is USB at the laptop end and goes into the Hand Controller socket at the mount. It was quite expensive so I hope it's not that!

[PhotoGav]

1 minute ago, ianpwilliams said:

I connect to my mount using one of those ASCOM cables from FLO, which is USB at the laptop end and goes into the Hand Controller socket at the mount. It was quite expensive so I hope it's not that!

I'm sure the cable is fine. If you can connect up to the mount and control it directly from the eqmod scope control panel then the cable is fine.

It is an annoying problem though. I have had complete system crashes as a result of the mount randomly disconnecting or the guide camera randomly disconnecting or the CCD randomly disconnecting. I think it is just part of the flakey nature of this whole thing. The only solution with APT appears to be a complete system restart.

[ianpwilliams]

I wonder if it might be worth turning dithering off in APT at the beginning of the session? Or better yet, maybe there might be an option in APT to not default to dithering being on from the previous session? After all, dithering isn't needed until everything is set up and imaging actually starts. I think I'll give that a go next session.

[Pompey Monkey]

9 hours ago, ianpwilliams said:

I wonder if it might be worth turning dithering off in APT at the beginning of the session? Or better yet, maybe there might be an option in APT to not default to dithering being on from the previous session? After all, dithering isn't needed until everything is set up and imaging actually starts. I think I'll give that a go next session.

Dithering only happens between exposures in a plan anyway. It's not your problem. The problem is the Prolific PL2303 chipset and drivers that are used with the <brand name omitted to avoid trouble> commercial cables. I had all kinds of problems with two cables using the Prolific chipset (one commercially purchased, the other home-brew) and spent many hours tearing my hair out over lost and no connection issues.

Eventually I made up a cable (for about £15) using a ready made FTDI usb to serial cable from Ebay with a standard CAT5 plug crimped on the end. It has worked faultlessly from the get-go three months ago. Instructions on the ASCOM website here: http://eq-mod.sourceforge.net/eqdirect2.htm

Unfortunately the Prolific chips are a lot cheaper than the FTDI versions. Go figure