PHD calibration question

[danielsun]

Hi, just wondering if anyone can help.
I have had my mount pretty much perfectly polar aligned with barley any drift but when I click on PHD to calibrate the mount to guidescope, after the 61 seconds it tells me that calibration failed because the star did not move enough.
So I have to pull the mount considerably out of polar alignment for PHD to detect the guide star movement and make it accept the calibration and begin auto guiding.
Is this normal or am I missing or doing something wrong?


Cheers Daniel.

[spearo (Frank)]

Hi
I'm by no means an expert on this but could it be backlash or the combination of backlash and the pulse settings (too short)?
cluelessly yours,
frank

[Robert_T]

Hi Daniel, I wish I had polar alignment that good

Have you tried putting a barlow into the guidescope - perhaps magnifying the image will magnify the drift enough for phd to "see" it.

cheers,

rob

[vash (Ashley)]

I had this exact same problem my first night out autoguiding with my eq6, mine seemed to be caused by the mounts autoguide rate. It was too low. try changing it to a higher rate. I have mine set to .5x but maybe you should try .75 or 1x.

[dugnsuz (Doug)]

I've had this happen occasionally - an intermittent fault...don't you love those!?
I checked balance, shut down and restarted PHD and it worked.
...also try the Autoguide speed as vash said - default setting is 0.5x.

On one occassion when PHD was acting strangely, I clicked on the little "brain" button and saw that a few of the values had changed from their default settings - don't know why!! But restoring the defaults remedied the guiding. Perhaps look there too.
All the best, shame to loose a decent polar alignment though.
Doug

[danielsun]

Thanks all for your replies and help.


I checked my auto guide speed and it is set at .5x, so I will try to change it to .75x or 1x and see what happens, or try the barlow.
It was a shame to pull my polar alignment out after having it near perfect but it was my last resort.
The manual even says to get the mount polar aligned as accurately as possible before starting.

Cheers Daniel.

[seeker372011 (Narayan)]

I have read somewhere-probably the Stark Labs yahoo group FAQ- that if you are trying to autoguide on a target nearer the pole you should change the default setting up from 500 ms for the calibration steps. Try 1000ms.

When you go to other parts of the sky a calibration step of 500 ms should generally work fine

PHD as you know tries to move the star a certain distance in each direction during calibration. If your mount is caught in some backlash loop this sometimes fails-the star simply doesnt move, in which case PHD gives up. Turning off PHD and starting up again sometimes works

[seeker372011 (Narayan)]

PS this has nothing to do with polar alignment-the better the alignment the better PHD should work anyway.