PHD - Little or no movement in the south

[zakkhogan]

Hi all, 

Been getting back out since we're all on lock down, Had some teething issues that Michael really helped me out with.  

Im getting guiding but wiht this issue: 'phd calibration complete but little or no movement in the south' 

 

Ive had a google and changed the  ST4 Lead but this didnt make a difference. Ive read about backlash but i dint really understand how to check it.

ive attached the PHD log.

 

Greatly appriciated

PHD2_GuideLog_2020-03-29_203347.txt

[michael8554]

No Dec movement until the Cal at 21:54 - what did you change ? If it was the lead then you've discovered that ST4 leads are unbelievable intermittant.

The Cal at 21:59 wasn't too bad, in 10 to 15 steps, but you only guided for 2m 36s, then Calibrated again (and again and again).

The calibration rates seem to alter every time, the one at 23:47 took 33 steps in RA !    Blue line.

With your ST4 setup you always have to Cal on a star near your target, because there's no feedback from the scope as to where the mount is pointing .

PHD2 would compensate the RA pulse lengths for different Decs if you had an Aux lead feeding RA and Dec positions back to the PC.

Or better still an ASCOM type guiding setup.

Check in the handbox that you have the Guide Rates set to something like 80% on Dec and RA.

Nudge the Dec north with the handset until you see the guidestar move, indicating backlash has been taken up, then do a Cal that takes 10 to 15 steps, if necessary alter the Calibration Step in PHD2 to get that number of steps.

Once PHD2 has accepted the Calibration was good, no error messages, run the Guide Assistant for a couple of minutes, accept the suggestions, ignore any messages about Dec Backlash for the time being.

Then guide for 10 minutes or so and post the Log.

 

 

[zakkhogan]

10 hours ago, michael8554 said:

No Dec movement until the Cal at 21:54 - what did you change ? If it was the lead then you've discovered that ST4 leads are unbelievable intermittant.

 

Thanks again for the reply Michael , i change the st4 lead and i also i was having an issue with the asi keep loosing signal repeatedly, error message was something like 'Camera failed to capture 2.5s of footage in 30 seconds' or words to that affect.

That issue was resolved by changing from ascom drivers to direct drivers (i believe) 

Originally on setting up i only had the option to select ASI Camera 1 or ASI Camera 2. There was no other option to connect the the camera. Knowing that i routinely  use the same camera, leads and laptop for planetary stuff i knew there was nothing wrong with that aspect of the set up, so just to be sure i opened sharpcap to check that the cam was working correctly (which it was)

With that the option to select ZWO ASI120mm became available in PHD and the camera ran smoothly and the ST4 connection in turn started to behave. 

 

I have the appropriate leads to atttach the handset to my laptop (As i have previously flashed my handset) and just now downloaded some more ascom drivers from the ZWO website.

 

Do think ascom is the way forward and  have you experienced the loss of connection with your ASI/PHD through ascom ?

really appropriate your help again 

 

All the best

[michael8554]

Any thoughts as to why your Cal steps were so variable?

Michael 

[zakkhogan]

3 minutes ago, michael8554 said:

Any thoughts as to why your Cal steps were so variable?

Michael 

Before i change the camera driver, the camera kept timing out and i kept getting the message  ' calibration failed: star didnt move enough' or somthing like that,  

When i googled it, it was suggested that i up the number of steps, would this be the cause? 

if so what should i change the steps to ?

[knobby]

Trial and error, try upping the steps by 50 %, see how it goes, then back down again if still working.

Also, give the guiding assistant a go.

[michael8554]

With an ASCOM connection PHD2 would know your Guide Rate and will provide the correct Calibration Step, once you've entered the correct guidescope focal length and guidecam pixel size. 

With ST4 it doesn't, so will Cal at its best guess of the Guide Rate, which I hope you have set at 80% or more. 

If that comes out at 10 to 15 steps then fine. 

But say it's 30 steps, then double the Step and try again. I'm assuming the Step has a linear response, it may not be. 

Michael