Synguider 2 - problems autocalibrating

[spaceman_spiff]

Hi everyone,

I'm restarting my astrophotography after a year or so out and I am having trouble with my Synguider 2. During auto-calibration it correctly calculates the RA movement but then it tries to complete the DEC drift calibration goes wrong. It basically hangs and then times out (after the timer hist 30). The  result is the RA aggressiveness has a reasonable value but the Dec is zero or near zero. I have to guess what the DEC aggressiveness is (about 2/3 of the RA) and it works fine.

Weirdly, it worked fine a year or so ago and once I have manually set the DEC aggressiveness it works well (which means the mount is receiving the guiding signals and moving properly).

The mount is a AZ-EQ6 and the guider is attached to a ST80 scope. The guider has the latest 1.2 firmware installed.

Any ideas?

Many thanks, Dan. ?

[michael8554]

If your mount has a lot of Dec backlash then the autocal may only take up the backlash and never move the mount before timing out.

So if the autocal moves the mount north, try nudging the mount north before starting the autocal.

Michael 

[spaceman_spiff]

39 minutes ago, michael8554 said:

If your mount has a lot of Dec backlash then the autocal may only take up the backlash and never move the mount before timing out.

So if the autocal moves the mount north, try nudging the mount north before starting the autocal.

Michael 

Good point Michael, I could also slightly unbalancing the DEC axis and see if that helps.

[spaceman_spiff]

Also, Is it worth altering the dec play feature? Will this be accounted for in the auto-calibration procedure?

[spaceman_spiff]

Just a brief report on the issue...

I am about to bring the scope in after a very good night guiding on M64 (the Black Eye galaxy). I added a 0.1s DEC backlash signal to the guider so it automatically provides a small amount of movement every time the guiding switches direction. I was worried about spurious small changes in direction causing an unnecessary backlash input so I increased the guiding exposure to 300ms to help prevent seeing conditions causing this issue (hopefully by smoothing them out a bit). I also slightly de-balanced the scope (both RA and DEC) and the auto-calibration procedure worked perfectly, no issues at all.

No meaning to brag, but my PA was excellent this time (one of the best I've done). TBH, I was easily getting round stars with 3 min exposures. I am not sure if this played a part in the issues with the auto-calibration procedure but I will bare it in mind next time.

Cheers,

Dan.

[michael8554]

5 hours ago, spaceman_spiff said:

so I increased the guiding exposure to 300ms

300ms, or 3000ms = 3secs ?

Glad you're sorted.

Michael 

[spaceman_spiff]

58 minutes ago, michael8554 said:

300ms, or 3000ms = 3secs ?

Glad you're sorted.

Michael 

Hi there, it was 300ms or 0.3 seconds. I know this is still a pretty short exposure and atmospheric seeing could still shift the guide star but I normally guide using 50ms exposures which must be worse! 🙂.