PHD problem

[CSM]

 I am trying to train my mount using PECTool and PHD2 with an Orion G3 Starshoot camera for guiding.  This is my first time of using PHD and although everything seems to be going fine after about 5 mins or so PHD gives a message saying that the star has failed to move enough. The PHD help says 

'The star moves during calibration but it moves "too far" or "too little."  This is easy to fix - simply adjust the 'calibration step-size' parameter in the 'Mount' tabs'

but gives no indication as to which way one should alter the step-size and have tried increasing (doubling) and decreasing (halving) it with exactly the same result.

Any advice would be most welcome!

Thanks
 

[Steve 1962]

From memory PhD needs the guide star to move about 24 pixels to successfully calibrate.

If it's reporting that the star isn't moving far enough, you can increase the guide pulse duration in PHD or maybe increase your mount guide rate if you have the facility.

Also - where is your scope pointing while you're trying to calibrate? You'll struggle if you're near the pole.

[CSM]

Thanks Steve.  Will try to increase the guide rate, if I can.  Am using Sadalmelik which is on the Equator.

[Steve 1962]

Does the star actually move? Have you confirmed that Phd is connected to your mount. You can do this using the manual guide buttons in PHD.

[CSM]

Hi Steve,  yes star did move but reading the manuals again I am pretty certain it is all down to the fact that I didn't have the star properly aligned in RA and DEC.  Will be trying again tonight.

[Steve 1962]

You don't need the guide star to aligned in RA and DEC - calibration works that all out for you.

[CSM]

Well after 3 unsuccessful hours I have come to the conclusion that I really am a dummy!  First hour not a program problem although PHD was complaining about the CameraXSize not active..  Reloaded Ascom and did various other things but eventually it was solved - take the computer cable out and put it back in again!

But the next 2 hours was spent constantly changing parameters and watching PHD trying to calibrate.  It did almost manage it once but then moved to the East step and lost the star.  Looking at the help and on-line it seems that calibration might be a bit of an issue!  Guess I will be looking for another program.  Anyone any suggestions?

[Phillyo]

Ok, go back to square one. Have you input the correct data for calibration? Pixel size, declination, duration, focal length etc? How far does the star move? How many steps does it take before it fails? Have you got the mount unparked and sidereal rate on? Are you pulse guiding through ASCOM or using ST4 guide port? Once the calibration completes (or fails) have a look at the result in the tools drop down, it can give you a good hint at what's going on and why it failed.

PHD2 works well once you've got it set correctly. And it's free

You'll get it sorted, keep at it.

Phil

[CSM]

Have been away over the weekend but this has given me a chance to read up on the software.  Basically I think it is all down to my stupidity - I never seem to be able to think outside the box when in the dark!  And now I think I have a much better idea of the mechanics and maths of guiding.  Will be using the simulator now and back outside when we next get a clear night.t.

[CSM]

After all the reading and studying and having run the simulator 'successfully' I thought I knew what to expect.  However  the results were no different.  Far too little movement and changing the step and various other parameters made very little difference from when I had the focal length set at 350 instead of 2350.  The polar alignment is ok - All Star followed by Drift Alignment and all set up permanently. Checked connections.  I am wondering whether to try the ZWO ASIMC120-S instead of the Orion G3 or what? Definitely cheesed off.  What a waste of clear skies!

[Steve 1962]

What exactly are you trying to do ..... guide or introduce some Periodic Error Correction?

If it's just guide - why are you using PECTool? You should be able to use PHD only with no extra software.

Can you share more details of your set up and maybe post a screen shot of your PHD settings please?

Thanks

[CSM]

Hi Steve - I may have solved the problem which is simply that of calibrating before doing any guiding.  Changed my computer over to my main laptop - no difference.  So used the ZWO ASIMC120-S and despite the difficulties of chasing an imaginary star in the daytime it was moving a lot more.  It appears the Autoguider port on the Orion G3 is faulty.  Doesn't matter as I intend to use that as the camera and the ZWO as the guider.  Hadn't used the ZWO as the PHD instructions slightly confused me as to how to operate it.  Tonight maybe!

[Steve 1962]

Ok - glad to hear you may be get

getting somewhere!

[CSM]

Success - yes it was a dodgy autoguider port.  PEC on mount looks quite good.  Next stage is to use it all and guide!

[solarboy]

Hi

I am having the same trouble

Maybe I should change my cables

Pete

[CSM]

Hi Pete - in my case it appears to be a dodgy autoguider port not the cable, maybe due to a bad connection.  I used the same cable with both cameras.