AVX / ZWO / PHD2 - all connected, but zero guiding

[Legion Of Andromeda]

OK, my current setup is an 8" Edge Hd plus DSLR on a Celestron AVX mount with a ZWO 120MM coupled with a spare 9x50 finderscope for my guidescope (yes, it's not ideal but i had this working fine with my Skywatcher mount) ...The mount is optically polar-aligned to begin with, with no cone error, the optical axis is in line with the RA axis, I go though all the usual stuff on the handset and the GoTo is accurate after a 2 star alignment and a 4 star calibration giving me great Sidereal tracking for 30 second exposures, reasonable for 60 seconds and not so good beyond that. .......So I have PHD2 set up on my laptop, the correct usb to serial cable between the laptop and mount handset with the latest drivers. i have the Celestron drivers added to PHD via ASCOM, I reset all the PHD settings to default, I then connect both the guidescope and the mount with no issues then fire up the guidescope refreshing once a second, the stars are sharp. I test the mount connection with the virtual handset in PHD and the mount slews very well. ...Then I auto select a guide star and hit the guding button and NOTHING happens, the star slowly drifts off from the crosshairs with no RA and DEC lines on my graph at all. Whilst there are dozen of settings i could play with in PHD, i feel that there is something very simple and fundamental thaty i have overlooked so i would appreciate any input. Thanks in advance.

[newbie alert]

Is it calibrated? bottom right circle green? 

Have you got the track rate, pixel rate of the guide cam , focal length of the guider..

Think 1 sec loop is too short but that's on my setup( I use 3) 

[david_taurus83]

Are you connecting via the handset? Are you using EQmod?

[michael8554]

As you thought, the mount moving with the Manual Guide buttons in PHD2 means that commands from PHD2 are getting through.

As Newbie Alert said, sounds like the mount has started to Calibrate.

So it's not drifting off, it's deliberately stepping West ten or so steps as determined by the pixel size and guidescope focal length in the "Brain" button.

Then it will do the same heading North.

When finished Calibrating the cross hairs will change from yellow to green and guiding will commence.

Did this not happen when you used the setup on the SkyWatcher ?

Michael

[Thalestris24]

Yes, you have to calibrate in PHD2 first. This allows PHD2 to work out the geometrical relationship between the guide cam and the mount. You also need to Polar align, and I use the PHD2 drift align tool. I find that the Polar Alignment has to be fairly close for PHD2 to calibrate properly - it's a somewhat iterative procedure. It also needs the mount + (scope + attachments) to be properly balanced. If anything causes a significant imbalance it can cause things to drift off. Once you have a successful calibration you can have PHD2 remember it. Oh, don't forget to make sure you have the guide scope focal length entered into PHD2 (Brain -> Guiding) and that PHD2 has calculated a sensible calibration step. I find it better to select a guide star manually and using a ~2s exposure, checking the star shape on the star profile display, especially not saturated, and ensuring you have a decent snr. Do make a dark library/bad pixel map. Presumably you've done all this before with the SW mount? It's easy to forget something - I know! Once you're all up and running, consider using platesolving rather than star alignment procedures. It's quicker and makes life much easier!
Good luck!

Louise

[Legion Of Andromeda]

Many thanks for all the replies and i should get a chance to deploy all the other suggestions tonight if the forecast holds up .... still early days with phd, my first try was on an EQ5 didnt need calibration (maybe it did it automatically and i missed it) and went straight into guiding for some reason,  so on my second attempt i assumed the AVX would do the same. Astrophotography would be no fun if it was easy.

[widotje]

Hi,

 

You need to do the star alignment first with your handcontroller or by using nexremote. Did you perform those steps? See my video on this, perhaps it helps:

Good luck and clear skies!