Dithering fails between APT and PHD2

[BrendanC]

Hi all,

Last night was my first attempt at guiding with PHD2. I'm running APT, controlling an NEQ6 mount under EQMOD via a direct connection, and have pretty much got that all working nicely now.

I got everything working and it all looked great... until dithering.

At that point the PHD2 chart went bonkers, while APT just said 'Dithering', and after 3 mins (the time-out limit), it, well, timed out.

I think there was an error in PHD2 too, about not being able to make sufficient RA adjustments. I'm kicking myself for not taking a note of exactly what that message was.

I've searched online and looked through the forums and don't really know what the next step would be to fixing this.

Given that these are my settings in APT, PHD2 and EQMOD below, can anyone spot anything that is immediately wrong? Or is there anything else I should be checking?

APT

PHD2

EQMOD

Thanks
Brendan

[almcl]

Not sure if this will prove relevant, but what is the dither scale set to in PHD2 (Brain, Global tab) ?

[Adam1234]

Hi Brendan, the reason it is timing out after 3 minutes is because your dithering timeout is set to 180s (3min), this isn't obviously the reason for your issue, this just tells the software how long to wait before giving up.

Looking at your settings, it may be the dithering distance and dithering stability set too high. A larger distance will take longer, and it may be that mount is struggling to settle. 

Not 100% though. If it helps, in APT I have dithering distance as 5, stability 0.7 (I think) and timeout 60s. 

 

Adam

 

 

[BrendanC]

Hey, thanks! Yes, I knew that was the reason for timing out at 3 mins, and considered extending that but it seemed pretty long already. I just didn't know why it was timing out. Great suggestions, I'll give them a try.

[david_taurus83]

13 pixels at 183mm focal length is a big dither. Try and lower down to 3 to start with and lower the timeout to 60s and the settle to 30. Keep an eye PHD and make sure it can recentre on the guide star within the 30s. If its comfortable you can lower the settle time even more.

[BrendanC]

Brilliant, thanks. I was just using the same settings as when I used APT Dither, didn't really consider the change in focal length, but that makes total sense because I'm now specifying the focal length of the guidescope, right? I'd already changed several settings which helped, but there are just so many variables it's difficult to know what to target next without a hint from the good people on this forum.

Post-edit: just spotted your signature 'Perennial cloud cover'. I sympathise...

Edited November 5, 2020 by BrendanC

[BrendanC]

17 hours ago, almcl said:

Not sure if this will prove relevant, but what is the dither scale set to in PHD2 (Brain, Global tab) ?

I have absolutely no idea! I'm going with the other suggestions and if they don't fix it, I'll be asking about that!

[BrendanC]

Hey, it worked! Dithering is no longer a problem. Ace.