Ideal PHD Guiding Settings?

[Matty P (Matt)]

Hi all,

I was just wondering if I could improve the accuracy of my autoguiding by changing the advanced settings on PHD?

The settings are currently set on default and I find that I sometime get some guiding errors that show up in some of my images.

Are there any settings that I can/should change to improve the accuracy of guiding?

Thanks in advance.

[iceman (Mike)]

What do you classify as guiding errors?

How accurate is your drift alignment before you begin guiding?

Wind and/or clouds will throw off the guiding.

Very bad seeing will throw off the guiding.

[Matty P (Matt)]

Originally Posted by iceman

What do you classify as guiding errors?

How accurate is your drift alignment before you begin guiding?

Wind and/or clouds will throw off the guiding.

Very bad seeing will throw off the guiding.

Hi Mike,

I would classify guiding errors as 'eggy stars'. I'm not sure what is causing though. Out of 5 sub frames, 1 or sometimes 2 have eggy stars.

My drift alignment was very accurate because I observed no drift.

Bad seeing or wind could have caused guiding errors but from my last imaging session. There was hardly any wind and the seeing was average but steady.

[g__day (Matthew)]

What is your guide scope's angular resolution at that focal length? How many arc seconds of space does each pixel cover versus what it the minimum seeing error before a guide command is issued? For instance at 1500mm focal length into a Meade DSI I set error around 0.4 of a pixel in great seeing conditions to 0.7 in poor seeing before a guide pulse is issued. At 2350mm focal length I used 0.7 pixel before a guide pulse is issued in great seeing to 1.2 in poor seeing with that guide ccd.

Secondly how frequently does your screen update - I found 3 second captures seem to give me optimal results to avoid chasing the seeing (I expect any guide correction will be very small, infrequent ~ maybe every 20 seconds, random in RA or DEC).

[multiweb (Marc)]

You might want to check this out. I found it very instructive.
http://www.stark-labs.com/movies/NEAIC08_Guiding.html

Originally Posted by Matty P

Hi all,

I was just wondering if I could improve the accuracy of my autoguiding by changing the advanced settings on PHD?

The settings are currently set on default and I find that I sometime get some guiding errors that show up in some of my images.

Are there any settings that I can/should change to improve the accuracy of guiding?

Thanks in advance.

[multiweb (Marc)]

and this too may help clear a few things:
http://www.stark-labs.com/blog/files/PHDSubpixelAccuracy.php

[Matty P (Matt)]

Thanks for the links Marc, I've got a lot of reading/listening to do.

Just a question regarding the PHD settings. When you click on the "brain" and the Advanced setup window pops up.

What settings do you guys have?

Cheers.

[Tandum (Robin)]

Matt,
Mine are pretty standard as I reinstalled PHD tonight. I tried the beta version to get my new QHY5 going but it just froze the mount so I uninstalled it and went back the the current version with a tweaked dll for the qhy5.

I've been shooting 10minute subs tonight fo the first time ever and have attached an image of the settings and a sample raw file. The raw looks like crap, remember we have a full moon, but the stars are round.