PHD guiding software: HELP

[PaulB]

Hi Guy's

I am using PHD to guide my G11 and I am having problems with frame dropping and guiding.

Firstly the Frame Dropping.

If I select anything below 3 seconds the screen goes blank but only for a very brief second then recovers. If I choose to guide around the 3 seconds mark this problem is more periodic. I use an Atik 2HS and an IBM T23 running Win 2000.

The next problem is my guiding.

Using PHD and the 2HS I have difficulty in getting nice tight round guide stars. I usually calibrate on my guide star at 2000ms and every thing looks good on the screen. But when I take a 300 second exposure using the Artemis capture software, my stars are not round, they are slightly elongated.

I use a William Optics Zenithstar 66sd (388mm) as my guide scope. And I image using an SPX 200-800 F4 from Orion Optics. The imaging camera is an Atik 16ic with Baader MPCC attached to a filter wheel.

My settings in PHD are

RA Aggressiveness 54

Hysteresis 20

Calibration 2000

Everything else is at default.

Can any body here offer any useful advice?

[dark knight]

Could collimation be an issue???

[Reggie]

Hi Paul, go to the tools menu and enable the graph, then look at the osc index on the graph, it should be between roughly 0.3 and 0.7 (0.5 is supposed to be perfect but PE will stop you achieving that). if its below 0.5 then up the aggressiveness a tad to get you closer. If its above 0.5 then reduce aggressiveness accordingly.

hth.

[PaulB]

Thanks Reggie,

I will try that tonight. I was wondering what the OSC was all about. And I have never had it between .03 or .07.

[PaulB]

Hi Reggie.

I can also send you an image taken last night.

Sorry Dark Knight, I didn't see your reply. I don't think that it is collimation because. I can see tiny movement after each 5min down load. So It must be Guiding, and It needs fine tuning.

[Psychobilly]

Well ... my guiding has got far worse since I "tweaked" my settings for the "ideal" OSC values.... now end up throwing away half my subs...where before I very rarely had to throw away a single sub...

So I'll be going back to the settings I used to use...and do it my way...it wasn't "broken" so I shouldn't have tried to fix it...

Peter....

[dark knight]

Hehehe Peter, we forever strive for perfection, but it always seems beyond arms reach. I've done the same thing when focusing and wished I never had, as I can never quite get it back to how it was.

[Reggie]

Oh dear, sorry to hear that Peter I did raise a question in this thread that I haven't had a reply to yet, I wonder if that may have happened? There's no way to reset the graph so this could throw things as you can't tweak aggressiveness without stopping guiding.

I've not noticed a great deal of difference closer to 0.5 apart from my graph appears smoother but then again my osc has always sat around 0.37 anyway, although I have noticed that in general it seems to need a little tweak each night out, but not much, possibly weather conditions affecting things for myself, I know you have an obs, so wind isn't an issue for you.

I'm going to continue to play with my settings and see what it gets up to, I don't seem to be losing any images through it. In Pauls instance though it would be a good indicator to start with, as we all have to set our aggressiveness etc. somewhere and everyones rig is different.

[Reggie]

With regard to my other thread, I can see it happen on my graph and on the capture screen I can see it move a pixel or 2 and also the green guiding point lines are off centre from the search box which phd then corrects(I can see it issue the commands), this data is then used as part of hysterisis I believe, so I think it could be reacting to this initial 'blip'.