“Dither in RA only” - SharpCap versus PHD2 controls?

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ChrisR Oz
Posts: 158
Joined: Tue Sep 28, 2021 11:03 am
Location: Melbourne

“Dither in RA only” - SharpCap versus PHD2 controls?

#1

Post by ChrisR Oz »

Hi Robin,

I current have “dither in RA only” set in PHD2. But I notice a similar control in SC guiding/dither settings. How do the two controls interact? Do you only request this from PHD when enabled? In other words, leaving it not enabled in SC will not “undo” my setting in PHD. Or must I make sure BOTH are set correctly?

Cheers, Chris.
Celestron EdgeHD 8, reducer 0.7x, Star Sense, CGX-L mount, Focuser, CPWI; Starlight Xpress AO, OAG and Filter Wheel; ZWO 294MC/294MM Pro and 174MM mini; SharpCap Pro, PHD2, Powermate 2x, Baader Neodymium, Astronomik CLS-CCD, ZWO UV/IR, Duoband filters.
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Re: “Dither in RA only” - SharpCap versus PHD2 controls?

#2

Post by admin »

Hi Chris,

honestly I don't know - the message SharpCap sends to PHD will include

Code: Select all

raOnly : True
or

Code: Select all

raOnly : False
depending on the setting in SharpCap, but how PHD combines that with its own setting I have never investigated. I think PHD2 has a fairly detailed guiding log that will probably record what it is up to in terms of dithering and give you the answer though.

cheers,

Robin
ChrisR Oz
Posts: 158
Joined: Tue Sep 28, 2021 11:03 am
Location: Melbourne

Re: “Dither in RA only” - SharpCap versus PHD2 controls?

#3

Post by ChrisR Oz »

Hi Robin,

Good idea. I looked in the PHD log, and it clearly gets a request with "raOnly":false, but then only dithers in RA only anyway, as set in the PHD settings.

19:07:44.340 00.219 11536 evsrv: cli 0CCF1C58 request: {"method":"dither","params":{"amount":20,"settle":{"pixels":3, "time":5, "timeout":60}, "raOnly":false}, "id":2}
19:07:44.340 00.000 11536 PhdController::Dither begins
19:07:44.340 00.000 11536 dither: size=20.00, dRA=2.54 dDec=0.00
19:07:44.340 00.000 11536 MountToCamera -- mountTheta (-0.00) + m_xAngle (0.01) = xAngle (0.01 = 0.01)
19:07:44.340 00.000 11536 MountToCamera -- mountX=2.54 mountY=0.00 hyp=2.54 mountTheta=-0.00 cameraX=2.54, cameraY=0.01 cameraTheta=0.01
19:07:44.340 00.000 11536 setting lock position to (77.29, 147.77)
19:07:44.341 00.001 11536 Mount: notify guiding dithered (2.5, 0.0)
19:07:44.341 00.000 11536 MultiStar: stabilizing after lock position change
19:07:44.341 00.000 11536 Status Line: Dither by 2.54,0.00

That answers that question.
Thanks for the suggestion.

I notice from this the request specifies the pixels to to "settle" to as 3. But for my guide camera (now at bin 2x2 and image scale 1.04 "/px), I should probably reduce that a little. It pays to look at logs ...

Cheers, Chris.
Celestron EdgeHD 8, reducer 0.7x, Star Sense, CGX-L mount, Focuser, CPWI; Starlight Xpress AO, OAG and Filter Wheel; ZWO 294MC/294MM Pro and 174MM mini; SharpCap Pro, PHD2, Powermate 2x, Baader Neodymium, Astronomik CLS-CCD, ZWO UV/IR, Duoband filters.
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