First go at PHD

[NickRose2006]

Last night I finally got the chance to try out auto guiding with PHD. The mount I have is the Vixen SP with GOTO Nova motors and the Guide scope is a celestron with a D=60mm and F=700mm. I am using a unmodified Philip Toucam Pro 740K. The graph that I have attached will show how bad the guiding was. My first guess is that maybe the polar alignment off and I need to redo my Drift alignment. When I did the 3 Star alignment it showed Alt: 52.8' Higher and Az: 89.1' east.

[swag72]

Can you post your settings in the brain icon? Often things can be improved with the tweaking of settings.

[Zakalwe]

It looks a bit lairy TBH. What refresh speed were you using (the little drop-down at the bottom of the screen)? 2.5 secs seems to work best for me.

Also, make sure that the scopes are not perfectly balanced. I go for camera and counter-weight heavy...it means that the gears are always engaged and backlash is prevented.

Try these things first....if it is still off, then your polar alignment must be out.

Here's my guide graph. Tripod mounted, polar aligned using EQMOD's polar alignment routine, no drift-alignment.

[NickRose2006]

RA Aggressiveness: 100

RA Hysteresis: 10

Dec guide mode: Auto

Dec Algorithm: Resist switching

Max Dec duration (ms): 400

Dec slope weight: 5.00

Calibration step (ms): 750 (I think, I don't remember what steps I had for this guide period)

Min. motion (pixels): .05

Search region (pixels): 15

Noise Reduction: None

Time lapse (ms): 0

Force Calibration: Yes

I was trying many different numbers with each setting but it was either the same or worse outcome.

[NickRose2006]

Refresh was 1secs.

[martin_h]

Try upping the refresh to 3 secs.

And I'd re check your polar alignment.

[NickRose2006]

Just curious, does it matter which side the motors are on. Mine are on the west side.

[James]

RA Aggressiveness: 100 (80)

RA Hysteresis: 10 (20)

Max Dec duration (ms): 400 (1000)

Calibration step (ms): 750 (1000)

On my setup with a 600 ish mm focal length my settings are a little different (in brackets after your figures above). As others have advised you need to check the balance (should be slightly off) and the polar alignment. If the PA is well off then no amount of tweaking will help you!

Having the max dec duration higher (and the calibration step too) helps take up the backlash on the Dec axis if you have any...

A longer guide sub of say 2-3 seconds will also help smooth out any fluctuations caused by bad seeing).

HTH

James

[Glider]

Was your Min Motion really 0.05? Try 0.5, not that it'll necessarily help you problem.

[NickRose2006]

So I guess it doesn't matter which side the Dec. motor is on east or west. Is it better for it to push or pull?

[NickRose2006]

Several nights ago I tried out the CCD Drift method. It actually worked out quite well. I could see that the drift for the South alignment was off but not as bad as the East alignment. It was a total of 5min. for each picture. I guess that's where my main PHD trouble was from. I think I'll have a free night tonight to test out the PHD and see if I get a better graph.

[NickRose2006]

Here is a update of my latest PHD guiding. I re-did the CCD drift alignment since I had to level my tripod, do to the driveway sinking to one side on a regular basis. Anyway the PHD guide did a lot better then the first time I tried it, with a much more level graph. Some info on the test picture with the star's. It was a 10min PHD guide with my 6inch F5 Reflector. Don't mind the stars near the edges, I guess that's due to it being a F5 scope.

[mark7331]

Hi Nick, your guiding looks pretty good now. I think the odd shaped stars round the edges are due to coma. You can use a field flattener to help with it. Here's an SGL thread I found that may help.

Nice result.

Mark