Guiding with PHD

[Coco]

On Thursday nigh I managed 5 frames on NGC6888.

My problem with PHD is if I 3 star align from west to east I sometimes get failed alignment, sometimes it aligned but wont clear the back lash,I now 3 star align from West to East.

I've followed RobH's suggestion of clearing the lash manually and this has cured the 'no DEC' warning, Ive also increased the calibration steps to 1000 , it used to be 500 , I am now only getting stars trailing N/S and am very happy with E/W...

My Guide Scope is an ST80 with QHY5

As far as a can fathom my scopes balanced with a little weight against the motors.. Any suggestions..

.

[Deneb]

you sure it's not your polar alignment..

[Ant]

Hi Mate,

What has a three star alignment got to do with PHD? I don't think I have ever done more than a 1 star alignment. When polar aligned well I've managed 20 minute subs.

How good is your polar alignment?

Cheers

Ant

[martin_h]

I agree it looks like you have drift due to dodgy polar alignment...I was looking at someones graph last night and it was exactly the same as yours.

He had polar aligned without the scope on, and after fitting it the alignment was a tad out due to (I think) the tripod settling due to the extra weight. A quick tweek and the graph was flat(ish)

[Sparrow]

Polar alignment doesn't need to be spot on for PHD guiding although obviously the more accurate the better - It might be a backlash problem. I think Craig Stark actually recommends turning off backlash in the mount handset now as PHD does the compensation for it. It might be that the two are fighting each other or causing an over correction.

[adamsp123]

Guy, try increasing the DEC max from 100 to say 300 and see what this does, it looks that PHD is trying, and somewhat failing to correct the DEC error then all the backlash is taken out and the mount over corrects.

Pete

[James]

As Peter says, bump up the max dec figure although I'd go up to 700 or 800...

[adamsp123]

As Peter says, bump up the max dec figure although I'd go up to 700 or 800...

Actually on second thoughts James is right then lower it in 100's to see what happens, importantly if you make any adjustments, change only one setting at a time.