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Old 06-01-2011, 03:41 PM
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telemarker (Keith)
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Question Sxv-AO mount bumping

Finally received a Lodestar camera to use with the AO unit. Managed to get the AO guiding for a max of 10 min before the guide star drifted outside the rectangle due to drift from polar misalignment. My question is how does one set up mount bumping with these units?

I was using an 8" SCT at f6.3 on an LXD75 mount with the ST-4 output from the AO fed into a 909 port autoguider. I've tried the SX lodestar program for guiding but it crashes on my vista laptop. Maxim works with the AO but this is where I have difficulties, how do you tell it to use the AO for bumping the mount? Any advice or experiences would be greatly appreciated.
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Old 06-01-2011, 06:15 PM
ericwbenson (Eric)
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OK, this is a real RTFM, but the answer for Maxim is the "Calibrate Drive" radio button on the locate tab of the main SX AO Control dialog. However bumping should be on by default in Maxim (see the Bump Time and Activation Level settings on the Drive tab), so make sure the mount is getting guider correction signals. You can test the guider signals with the regular guider controls on the CCD window (for example regular guiding or use the Move dialog).

Good luck,
EB
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Old 06-01-2011, 06:49 PM
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multiweb (Marc)
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Hi Keith, TBH I didn't bother with the mount bumping. I guide with a QHY5 on a finder separately and have the AO with the lodestar on the OAG doing its thing. It's a no brainer and it works.
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Old 07-01-2011, 07:40 PM
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telemarker (Keith)
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Thanks for the info guys. Well I had better do some reading then. In then interim, gave Marc's method a go. It seems to work OK but is sensitive to cloud, moreso than the finderguider which makes for some interesting star patterns. I'll keep playing with it.

Last edited by telemarker; 07-01-2011 at 09:33 PM.
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Old 07-01-2011, 08:07 PM
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bert (Brett)
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Hi Keith,

Take the time to do get it working properly with maxim drive calibration. I set the bumping threshold at 25%. The advantage of this is the ability to dither via ao in the autosave menu, which makes a huge difference to the noise characteristics in my camera. I personally set the bumping threshold at 25% of deflection.

If it is the same menu as the sbig ao in maxim, just choose mount calibration where you select 'find guide star' in the ao window.

HTH
Brett
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Old 09-01-2011, 04:41 AM
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telemarker (Keith)
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Thanks Brett, second go last night got it guiding for over an hour. Very neat when it ticking away and the stars were oh so round. My main battle is getting the calibration to work, it auto selects hot pixels and has a big whinge when they don't move. I can't for the life of me see how to dark subtract from the guider's image and only got around it by exposing for 10 sec at 4x4 binning where it'll select a star not the hot pixel.

Regards
Keith
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Old 10-01-2011, 09:38 PM
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telemarker (Keith)
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Just a quick image. NGC3576 30 min in 5 min subs using 127ED with Orion SSDSI and SXV-AO. No flats, stacked in DSS, PS for curves and levels.

One is full frame and the other is a 100% crop. Happy with the star shape and very little movement between subs. Now for some clear nights.
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