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Old 19-09-2014, 04:15 PM
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codemonkey (Lee)
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codemonkey is offline
Join Date: Jul 2013
Location: Kilcoy, QLD
Posts: 1,522
Originally Posted by Octane View Post
It's all a mystery!

You need to buy a Paramount ME II.

haha. That's it! I'll let the wife know what to get me for christmas ;-)

Originally Posted by DJT View Post
Graph 2 is interesting. You have an FWHM of over 6 on your guide star but your guide exposures are just 1 second. Chasing seeing? Your other graphs have fwhm between 3 and 4. The intent is to make as few adjustments as possible so take longer guide exposures? Also gives all your other settings less to deal with.
I suspect this is actually it. I still see stars bouncing all around the place even when guiding is disabled so this suggests to me either:

1) Seeing
2) Mount problems
3) Physical instability somewhere

I saw a thread saying that my area has had terrible seeing lately, so maybe that's all it is. I've done exposures up to 5 seconds long to try and offset seeing, but I was still seeing the star bouncing around from exposure to exposure.

Originally Posted by Shiraz View Post
you need to recalibrate phd when you change the guide rate - otherwise it will not compensate by the right amount and you will see wild swings.
Yeah, while that's obvious I'm not actually sure if I did that or not lol. I'll try it again.

Originally Posted by Amaranthus View Post
Yep, as Ray notes, you MUST recalibrate PHD after making a change in the sidereal rate - otherwise the corrections will be 5 times too large compared to its training movement! I'm still convinced this is the problem.

-- Set guide rate at 0.5x sidereal in ASCOM (leave other settings as is).
-- Set exposure to 3 sec.
-- Set noise compensation to 2x2 mean.
-- Set RA aggr to 80 and Hyst to 15.
-- Set DEC to resist switch.
-- Set min movement of both to 0.25 pixels.
-- Set max RA and DEC movements to 1000 ms.
-- Point at DEC 0 and maybe 5 degrees east of the meridian.
--(Re)Calibrate PHD. Make sure that calibration used at least 8 steps (if not, adjust the pulse duration in the Brain settings).

Do all this, and report back
Thanks mate! I'll try that tonight if the weather holds

Originally Posted by mithrandir View Post
Lee, you can't change it in EqMod. You have to edit the log before PHDLab can cope.
Ah ok, that explains why I haven't seen a setting for it. Thanks :-)
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