mark7331

Adam, sorry you're still having trouble. How long are the gaps between the peaks in DEC activity? Do you get, for example, 5 minutes of smooth guiding then a blip?

Maybe you're right about the mount but I wonder is there a way to test it? Could you, for example, use an artificial star and see when (or if) the mount misbehaves?

If you can get 5 minutes of good guiding then maybe that's acceptable for the mount...

Mark

Ouch. I hope it's not mechanical.

Just a thought Bamus but have you tried, once calibrated, reducing MxRA and MxDEC. Maybe PHD is over compensating? Try 500 ish?

Mark

You really shouldn't be changing the guide rate simply to achieve a certain "calibration" result.

Hi Chris,

I completely agree but just to clear this up I'm not looking for a certain number of calibration steps to get guiding working. They are just an indicator that the settings are OKish. The point of changing the guide rate is that the mount doesn't take enough notice of the guide commands when the values are set too low. I started, by mistake, with both RA & DEC set to x0.10 and for ages have struggled to get the mount to keep up with the guiding. Once I changed the rates (to x0.30) my guiding started working.

My approach is to get a guide rate that works well with a calibration step. If it's too low it doesn't.

Regards

Mark

Bamus, glad to help mate

The EQMOD pulse guide rate should be set before you calibrate and if you need to adjust it again you should re-calibrate PHD because it's a major change to the responsiveness of the mount.

I'm not sure you're going to need to set the backlash value in EQMOD. Once your calibration is reasonable in DEC it may not be an issue any more (mine is also "0") but maybe that's because I have different mount? So I can't find a direct way of measuring the backlash but I wondered could you use the EQASCOM trace feature to work it out? Right click on the ASCOM logo in EQMOD to see the trace. If you watch/record the log while PHD is clearing backlash it might give you an idea of the number of ms you'll need. I checked the PHD debug log and I couldn't see any backlash related data.

Just to be thorough I have the EQMOD minumum pulse width set to 20ms. My RA guide rate is x0.30 and DEC is also x0.30.

I'm really interested to see if making these changes takes out your DEC bumps (as it should do) as it would be great to have a clear procedure for getting rid of these kind of guiding issues.

Keep us posted.

Mark

bamus sorry if you know this approach already but I thought it might help to share my method for calibration. I understand your frustration, I've experienced it myself, but there should be a fix for reasonable guiding.

So:-

I started by working out a calibration step value that produces between 10 and 20 steps when calibrating. Leave everything else as default until you can produce this. If you're using EQMOD you can change the RA & DEC Pulse Guide rate to help reach the calibration "zone" you're looking for. If you're using the ST4 (Autoguider) port then adjust the guide rate to help - you may need to do this with your handset.

Once you've found a good calibration step/guide rate pair then take some exposures of increasing length and modify the MaxRA and MaxDEC durations. Once you have a reasonable image then tweak the other settings (RA agressiveness, hysteresis etc) to smooth further if you need to.

In my experience the guiding graph isn't really a useful indicator of good guiding. I've taken some long exposures where the stars are perfectly round but the graph has appeared quite bouncy. So my message is don't worry too much about the graph. Take some subs, note the settings you used to get them and compare to previous subs. You may find you're getting good images with a crazy looking graph.

Sorry if you've heard this all before but I hope it helps.

Mark

Forgot to mention that on my birthday my other half order me an Ha 7nm filter. I already had one and after a quick phone call the guys at FLO said "send it back and well send you the OIII you asked for :)". Simply the best service anywhere. Thanks guys.

Just thought I should say something about Modern Astronomy.

I'd not ordered from them before but I wanted a QHY5 and couldn't find in on my usual sites (FLO,Greenwhich). So I placed the order early yesterday morning. Received lots of emails about the order progress and this morning my shiny new guider camera turned up barely 24 hours after the order.

Brilliant service.