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  #61  
Old 19-09-2014, 05:01 PM
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codemonkey (Lee)
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Quote:
Originally Posted by Peter.M View Post
Not to beat a dead horse here, but did you actually take an image with your main camera yet? The last graph that you said was "best one but still not good" shows +- 1 arc second (assuming that your graph scale is set to arc seconds and not pixels, and assuming you have entered your focal length in phd2)

That would be quite acceptable to me on most nights.
I did take some exposures last night and the stars were malformed and much larger than they should have been (I didn't save them, though maybe I should have in retrospect).

That one was taken with the guide cam through the focuser rather than the OAG; the OAG seems to make it worse, presumably due to star shape.

That graph also ranges from +2" to about -1.5" which gives me a range of ~3.5".
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  #62  
Old 19-09-2014, 06:41 PM
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Quote:
Originally Posted by codemonkey View Post
I did take some exposures last night and the stars were malformed and much larger than they should have been (I didn't save them, though maybe I should have in retrospect).

That one was taken with the guide cam through the focuser rather than the OAG; the OAG seems to make it worse, presumably due to star shape.

That graph also ranges from +2" to about -1.5" which gives me a range of ~3.5".

Tonight I am taking some exposures, I will screenshot my graph for you and post an image.
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  #63  
Old 19-09-2014, 08:22 PM
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Quote:
Originally Posted by Peter.M View Post
Tonight I am taking some exposures, I will screenshot my graph for you and post an image.
Thanks mate, appreciate the effort :-)

Good news! I'm taking some 4 minute exposures of the helix nebula as I write this, and the stars are (mostly) round! Interestingly on one side of the frame they're consistently less round, but that's a topic for another day. Probably something not quite square I guess.

So, I followed Barry's advice to the letter but I still had a not-so-great looking chart. I ended up reducing the numbers significantly, now to 40% aggression, 15 hysteresis, 0.4 min move on RA and 0.5 on DEC, which reduced it somewhat but it's still looking pretty damned horrible.

One thing of note is that I managed to tweak the OAG until I got almost round stars in PHD2, which I've never been able to do before.

So I think Peter was on to something there. Even though the charts looked terrible that doesn't mean the results were... although sometimes they have been and now tonight, it's not.

The stars are still bouncing around, which I think is the real cause for the horrible chart, and I'm putting that down to seeing at the moment.

So now I should be able to grab a couple of hours of luminance on the helix before I have to pack it up and wait for the next clear night to get some RGB... which looks like it may not be coming soon judging by the BOM.

Thanks everyone for your help, I really appreciate it!
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  #64  
Old 19-09-2014, 10:18 PM
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Make that 10 minute exposures... first time ever I've hit the 600s mark
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  #65  
Old 20-09-2014, 12:00 AM
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Results from tonight: not too shabby considering I didn't expect to get any imaging done at all.
Attached Thumbnails
Click for full-size image (helix.jpg)
133.0 KB64 views
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  #66  
Old 20-09-2014, 12:53 AM
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Stars look nicely shaped- glad it worked out!
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  #67  
Old 20-09-2014, 10:28 AM
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Quote:
Originally Posted by alpal View Post
I couldn't get my NEQ6 pro mount running properly until I had
the Dec & RA backlash adjusted & I also fitted a better counter weight bar
as per here:

https://www.flickr.com/photos/247194...in/photostream

Hi Lee,
Did you read my post above?

Have you got a standard NEQ6 pro with a wobbly counterweight bar?

(easy to check - remove the counterweights & move the bar
back & forward to check how much play is there. )
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  #68  
Old 21-09-2014, 07:18 AM
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Originally Posted by alpal View Post
Hi Lee,
Did you read my post above?

Have you got a standard NEQ6 pro with a wobbly counterweight bar?

(easy to check - remove the counterweights & move the bar
back & forward to check how much play is there. )
Sorry mate, I missed that one. I assume that it's the standard counterweight bar (I bought it second-hand). I haven't checked to see if it wobbles, but it sounds likely. Definitely worth looking into!

I did a quick look around and found that Orion sell upgrades meant to fix this, quite cheaply too, but I'm not sure if anyone in Australia stocks them and they don't seem to ship internationally. I'll have to keep looking. Thanks for the tip!
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  #69  
Old 21-09-2014, 08:17 AM
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Quote:
Originally Posted by codemonkey View Post
Sorry mate, I missed that one. I assume that it's the standard counterweight bar (I bought it second-hand). I haven't checked to see if it wobbles, but it sounds likely. Definitely worth looking into!

I did a quick look around and found that Orion sell upgrades meant to fix this, quite cheaply too, but I'm not sure if anyone in Australia stocks them and they don't seem to ship internationally. I'll have to keep looking. Thanks for the tip!

No worries - it will definitely improve your closed loop performance & stability.
It's only a minor thing to fix but the results will amaze you.

I noticed they fixed it up in the latest EQ6 mounts. ( belt drive - I think )

cheers
Allan
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  #70  
Old 27-09-2014, 10:08 AM
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The last couple of PHD2 snapshots include the limit warnings. http://openphdguiding.org/snapshots.html

  • display statistics about max RA and Max dec limit reached in the stats window
  • show a warning if ra or dec duration limit is consistently being hit
  • add information to GuideStep message if max RA or Dec limit is reached
  • send notifications to event server clients when any alert message is displayed in phd2
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  #71  
Old 27-09-2014, 10:50 AM
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Gday Andrew

Can you ask em for a means to test for "Alien abductions" :-)
I am currently working with someone using a CEM60-EC and was collecting data at about 1-1.5 second rates.
I have my own plotting app running now and was looking at the detailed frame time data ( for consistency of timing ) when i noted something very weird.
The logs timestamp went backwards by 4.5 seconds between 2 frames????
I have seen this effect once before, and have no idea what causes it.

Andrew
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  #72  
Old 27-09-2014, 11:10 AM
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Hi Andrew,

Quote:
Originally Posted by AndrewJ View Post
Can you ask em for a means to test for "Alien abductions" :-)
That should probably be part of a generic test for all fruit-cakes. :-)
Quote:
Originally Posted by AndrewJ View Post
I am currently working with someone using a CEM60-EC and was collecting data at about 1-1.5 second rates.
I have my own plotting app running now and was looking at the detailed frame time data ( for consistency of timing ) when i noted something very weird.
The logs timestamp went backwards by 4.5 seconds between 2 frames????
I have seen this effect once before, and have no idea what causes it.
Was it just one record with a backward jump or was it monotonic increasing after the jump?
If it was just one, PHD2 is multithreaded so it could be one thread blocked between generating the log record and it being written.
If it was monotonic after the backward step maybe something is resetting the clock. I use NTP so the only time the clock can jump is at NTP start.
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  #73  
Old 27-09-2014, 11:29 AM
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Gday Andrew

Quote:
Was it just one record with a backward jump or was it monotonic increasing after the jump?
The latter. I had seen this once before and just put it down to a glitch on the users PC, but a different user on a different PC sent me a log last night that has the same quirk, so now i'm a bit more confused/bemused.
Will try to find the old log to see how much the time step was then.
Its self healing for normal guiding purposes, but we were doing more of a very detailed datalogging exercise to watch the encoder feedback looping in the mount, so it showed up.
Nothing like donuts in yr plots :-)

Andrew
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