PHD2 and ZWO guide cameras

[Merlin66]

There appears to be some issues with PHD2 and ZWO cameras...

Requested test procedure:
- download and install the test version from https://openphdguiding.org/phd2-2.6.5dev6zwotest2-installer.exe
- calibrate if necessary
- run the Guiding Assistant and let it measure Declination backlash
- enable PHD2 backlash compensation if the GA offers that suggestion
- guide for a several minutes, long enough to see some declination guiding direction reversals and some backlash correction pulses
- upload your PHD2 guide log and debug log from the session (https://openphdguiding.org/getting-help/)

The PHD guys say:

We were able to track down the problem and it turns out to be related to PHD2 retrieving stale data from the ZWO camera -- camera frames that started exposing before the backlash guide pulse finished. We got some help from ZWO and have a new build of PHD2 ready for testing. We believe this will fix the backlash compensation overshoot issue and generally improve guiding for ZWO cameras. We would like some help testing it.

[Startrek]

Hi Ken,
Do you know which ZWO camera’s are causing an issue when PHD2 guiding ?
I use a ZWO ASI120MM USB3 camera and I have been guiding ok recently
DEC has been good but RA a bit high , adjusted counterweights slightly east heavy and RA improved

Cheers
Martin

[Merlin66]

Sorry, I can only make you aware of the issue....
I use a Lodestar for guiding, so have no experience with the WZO guide cameras.

[Startrek]

Thanks for the heads up anyway

[kens]

Its all the ZWO cameras. If you don't use backlash compensation you probably wouldn't notice it. PHD2 runs ZWO cameras in video (streaming) mode. With backlash compensation the correction can be long enough to still be going when the next video frame is taken which creates a trail on the guide star. Not sure if the fix pauses the stream or switches everything to snapshot mode. I know with some cameras, snapshot mode causes a delay so I might give this one a test tonight.

[ChrisV]

Where's the link to this? I haven't had any zwo issues, but I am running the latest version 2.6.5dev6 with an asi290mm.