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Old 02-09-2013, 11:25 AM
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Odd guiding behaviour

I am using an SBIG ST-I in OAG of QSI683 with a TSA102 at f5.7 and maximDL to guide with, as well as CCDautopilot.

Last couple of nights I have seen some odd behaviour with guiding. Whilst imaging in the Milkyway star field I have no issues at all. Guiding exposures at 3 seconds, guiding optimal.

Move out to NGC300 where there at not many stars and I get star faded a lot. I can see the guide star selected but it still reports star faded in MaximDL. This is happening whilst going through CCDautopilot.

Now if I stop the guiding and click expose and then click on the guide star I get perfect guiding. No star fade.

To complicate things couple of nights ago I took off the guide camera because the shutter was not opening properly after doing a dark. I think it was power related as I plugged the USB cable straight into the computer and the shutter opened and closed.

I wonder if the USB is not getting enough power to open the shutter all the way up, as when I took the guider off the OAG the shutter was only opening by a slit of around .5mm. It was a miracle it could guide at all.

I have checked with another ST-I guider that has barely been used and it is doing the same thing when plugged in the way it was.

Would this be power or could it be some setting in CCDautopilot that is causing the problem?
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Old 02-09-2013, 11:33 AM
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For what its worth I use an STi guider and it plugs into the USB port of my FLI Proline. Its been reliable and I haven't seen that at all.
Are you able to measure the voltage from the USB port. It should be 5 volts I am pretty sure.

Greg.
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Old 02-09-2013, 12:14 PM
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2 things.

1. Ensure small stars check box is ticked in the guide tab in maxim.

If that does not work, use longer guide exposures or switch to ccdsoft.
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Old 03-09-2013, 07:09 AM
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Hi Paul,

This might not be useful because I don't use the programs you are using, but I think you might be onto something power related. I had an issue with my ST-i where it was quite unreliable over a longish cable length. I added an inexpensive powered USB hub and the problems all vanished. Maybe just try that before changing software.
Peter
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Old 03-09-2013, 08:14 AM
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Little bit of and update. Last night I tried something different.

I ran enable auto guide exposures. For some reason it preferred to have exposures at 10 seconds while I watched. So I can only assume this was the case after I went to bed too as I have nice round stars in all the exposures taken after I went to bed.

Oddly though, I found that I could guide on another star in Maxim which was dimmer than the one selected all the time by AP if I took an image manually and told it to guide. It would guide happily at 4 seconds and yet when AP was doing the selecting it could not see it. Once I enabled auto guide exposures it worked. Very strange.

So perhaps it is also been the case that as well as the shutter not opening properly when going through the extender cable, but also the stars were too dim for AP and maxim to guide on at 3-4 seconds. Time will tell I suppose but it appears quite strange.

Happily I awoke to the roof being closed but AP had tried to restart 5 times since it shut down the first time. Some weird glitch I have seen before where it will try restarting despite completing the run. Like Rally has said, it is most likely multiple causes for such behaviour. Everything trying to draw power and work at the same time. Sort of like a needle in a hay stack. I will keep looking.
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Old 04-09-2013, 10:19 AM
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Sounds good Paul. What's AP?

Greg.
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Old 04-09-2013, 10:24 AM
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Greg, that is my short hand for CCDautopilot. Sorry I am getting lazy.
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Old 06-09-2013, 02:36 PM
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Thanks Paul.

Ah the joys of conquering another wall of software!

Greg.
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