PHD Settings with OAG and Lodestar

[John K]

Hi guys,

I had my first go at using my Lodestar guider with an OAG last night but could not get tracking accuracy at all.

I am wondering whether in terms of PHD settings there is a correlation in settings for a specific mount when comparing the focal length that the guiding is done at.

So far, I have been using an 80mm f3.7 300mm fl. short focus refractor to guide with, but even though the graphs on PHD look perfect, smaller stars are never perfectly round and I am getting some flex in the system as well. I am shooting with a 12.5" f/5 reflector and a DSLR.

The setting that seem to work on my mount with the 80mm short focus refractor are as follows:

Drive set to x0.5x
RA Agress: 78
Ra Hys: 48
Min Motion: 0.05 pixels
Mx Ra: 815
Mx Dec: 102
Avoid switching in Dec
Caligration: 1500

So the question now is, if I use the OAG, but guide at like 1500 mm f.l., what should my settings in PHD change to?

I tried all types of settings last night but for the life of me could not get an kind of accurate tracking!! Very frustrating as there is great potential here!

I would like to move to the OAG as the Lodestar is super sensitive and guidestars are not an issue and this will remove the flex issues I am having.

Any suggestions really welcome!

Clear skies.

John K.

[Merlin66]

John,
I use a version of an OAG (reflective slit guiding) on my C11 at f10 with a Lodestar guide camera...
I'll double check the settings I use on PHD 1.13, but I'm almost sure I just use the defaults....
Good adaptor connections (Threaded parts given a smear of boot polish!) and good balance I think are the key....
If I find the settings are different, I'll edit this post.

[White Rabbit]

I'm no expert but your RA Hys seem to be very heavy handed. I dont use an OAG but mine are set to under 10.

[John K]

Thanks for the info guys.

I lowered the calibration to between 300 and 500 and all else was left the same.

Have now been able to get 5 min subs no probs!

Very happy.

John K.

[White Rabbit]

That's weird that your calibration would have an effect on your guiding accuracy. Like I said I'm no expert but I though calibration only tells the software what angle your camera is? Shouldn't effect your accuracy.