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Old 11-10-2009, 09:12 PM
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Guiding error update

Hi Guys here is an image of what happens when my guiding started to play up, can anyone detect from the odd star trails what could have caused this.

Leon
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  #2  
Old 11-10-2009, 10:12 PM
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[1ponders] (Paul)
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Jeez Leon, you haven't swapped the DEC and RA cables around accidentally have you.
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  #3  
Old 12-10-2009, 09:19 PM
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No Paul nothing has been changed, but something is certainly not happy, when I get a chance I will give the whole set up a good service, connections, lube, the lot.

Leon
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Old 12-10-2009, 09:34 PM
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Hmm, looks quite strange. The first thing I would do, is check all nuts, bolts and grub screws that fasten drive gears to shafts and worms etc, to make sure that one hasn’t slightly worked loose and is allowing a gear to slip on a shaft in an ad hoc manner.

Cheers

Dennis
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  #5  
Old 12-10-2009, 09:58 PM
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Hi Leon

Im no G11 expert, however experience in my proffesion has taught me that when ever you have a closed loop type system that fails, you have to open the loop and fault find from there. In this instance stevie wonder could tell you that the guiding is stuffed. A simple way of isolating it to either mechanical or electronic could be unplug the auto guiding and see what the mount comes up with by itself over a minute or two. You may find that the guiding is not perfect but it definitely is somewhat better in a way, and you may not. The only experience I have had with images that look like this was a mount that had faulty electronic operation. The tracking would be ok until the system started making huger error corrections to try and get the guide star back.

If you get an identical result then you probably needn't look at the error correction side.

Hope this helps.
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  #6  
Old 12-10-2009, 10:08 PM
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Hmmm, thank you Jeff, excellent idea, the steps of elimination, sounds like the way to go.

Leon
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  #7  
Old 13-10-2009, 09:33 AM
TheDecepticon
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Hi Leon,
It really looks like it is wind affected. I've seen it before and it looks very similar to this.
Cheers,
Gray.
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  #8  
Old 13-10-2009, 12:49 PM
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Thanks Gary, I would discount that with this particular imaging run as it was pretty quite on the night, and I have imaged in windy conditions before.

Thanks for your response however.

Leon
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  #9  
Old 13-10-2009, 06:22 PM
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an earth tremor or traffic vibration?
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  #10  
Old 13-10-2009, 06:24 PM
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Wild guiding if you ask me. And in two axes as well, not just "no guiding" so elongated stars, but a bit of both. What is the guide camera Leon? While it is possibly not in your case, some guide (or think they are) on a hot pixel.
Guide-scope not loose?
Gary
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  #11  
Old 13-10-2009, 06:26 PM
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Quote:
Originally Posted by scopemankit View Post
an earth tremor or traffic vibration?
I thought I was seeing an earth tremor while looking at Jupiter the other night until I noticed the cat rubbing against the EQ5 mount LOL.

I hope you can sort this one out Leon.Must be frustrating.
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  #12  
Old 13-10-2009, 06:39 PM
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Ah, yes, the cat attack, I'll second that Leon, not got a Moggy that likes your pier? Mine wrecks the occasional image.
Gary
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  #13  
Old 13-10-2009, 09:08 PM
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Frustrating is right, and more so now that it is wet and cloudy so I can't even get out there and try and fix it.

Gary, it is very weird indeed, but i feel it will have a simple explanation, I hope.

Gary I use the Orion StarShoot, and it has performed perfectly until now.

Leon
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  #14  
Old 14-10-2009, 10:08 AM
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I've had similar results when i first starte guiding and it turned out to be the settings I had in PHd. Might not be your problem but that what it was for me. check that you havent changed any settings by mistake.
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  #15  
Old 14-10-2009, 12:16 PM
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Yep I will have a look at the Mr Rabbit.

Leon
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  #16  
Old 14-10-2009, 07:43 PM
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What FL was this sub taken at and what was the exposure time?
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  #17  
Old 14-10-2009, 09:54 PM
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Looks like PHD lost the guide star temporarily and then corrected for it?
Thats quite a shift in position though, and the drift would have been bad to move that much.
Guidescope secured correctly? Guiderings not tight enough ?
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  #18  
Old 15-10-2009, 07:39 AM
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Quote:
Originally Posted by leon View Post
Frustrating is right, and more so now that it is wet and cloudy so I can't even get out there and try and fix it.

Gary, it is very weird indeed, but i feel it will have a simple explanation, I hope.

Gary I use the Orion StarShoot, and it has performed perfectly until now.

Leon
Leon, the best thing about the G11 is its modular design. It's like LEGO blocks. You can pull it apart in 5min and put it back together in 10. If you've never opened it then the most likely culprit is clutch slippage. The nylon discs get greasy over time. The grease will come from the bearings, mostly in RA. You don't even have to take the worms out to rectify this. Unscrew the knob at the end of each axis and take off the thrust bearings at the end of each shaft and slide off the axis. You'll see the discs. Give them a good clean with a rag and alcohol if necessary and try again, see if it makes things better. I actually glued mine on the bearing side with rubber Gel Grip to get higher break away friction.
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  #19  
Old 22-10-2009, 09:15 AM
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Leon
Are you using PHD? There has been a bit of a thread on the Stark labs website about people's guiding going off for no apparent reason.
Geoff
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  #20  
Old 23-10-2009, 01:32 PM
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Quote:
Originally Posted by ghsmith45 View Post
Leon
Are you using PHD? There has been a bit of a thread on the Stark labs website about people's guiding going off for no apparent reason.
Geoff
Yeah I've noticed that for the past couple of months. Loads of heated discussions about it. Since the 1.10.x batch of PHD was released. I have also noticed PHD is a bit more aggressive in RA and "slacker" in correcting DEC with the default settings but tweaking the parameters fixed all that. Most of guiding errors were mechanical or balancing on my end, not the software. Have you had issues with the GM8 and PHD?
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