Dithering timing out (APT/PHD2)

[Stuf1978]

Hi All,

Lately I have been having issues with dithering timing out. I'm using:

HEQ5 Pro via EQMOD

Canon 450Da 

SW ED72 or a range of lenses

SW 50mm guidescope with ZWO ASI 120mm mini

Image capture in APT with guiding via PHD2.

I haven't changed anything in my setup or any settings within APT or PHD2. The last few sessions dithering would start but then timeout and APT would continue with the next exposure. I'm dithering after every exposure and the timeout is effecting maybe 80-90% of the individual subs. Looking at PHD2 the dithering is taking place but not sure why it's timing out. 

This is frustrating as hell considering I haven't changed anything.  Has anyone else experienced this?

Thanks

Stu

[david_taurus83]

How much are you dithering? If the mount has backlash it can take a while for PHD to recentre on the guide star. The Dec axis is usually the worst for this.

[Stuf1978]

20 minutes ago, david_taurus83 said:

How much are you dithering? If the mount has backlash it can take a while for PHD to recentre on the guide star. The Dec axis is usually the worst for this.

The dithering distance is set to 5 within APT which as far as I can gather equates to 5 guide camera pixels as the dither scale is set to 1 within PHD2. 

I've just stripped and regreased the dec axis as it was running a bit stiff however I encountered this issue both before and after the strip down. For what it's worth the dec axis is running more smoothly but nowhere near as freely as the RA axis. There is no play at all in the dec axis so there should be minimal backlash. 

[david_taurus83]

When it dithers does it recenter on the star before the next exposture starts?

[Stuf1978]

16 minutes ago, david_taurus83 said:

When it dithers does it recenter on the star before the next exposture starts?

I'm not 100% sure to be honest so I'd have to check the next time I run it. The graph definitely hasn't settled when the next exposure starts. However, this doesn't seem to be effecting image quality as far as I can see.