Ok Using CCD Calc I get the following numbers for your setup:
Guider 2.68 arc sec per pixel
Camera: 1.92 arc sec per pixel
Good news is this guider and camera combo should theoritecically allow you to guide at around 0.6 arc sec per pixel accuracy. Reality depends on your mount, camera connections. ie how tight your guide scope and camera and main camera and scope are coupled. How tight your guidescope is coupled to main refractor etc... Double check all of these things and tighten evrything up as much as possible.
So depending on your local seeing conditions. Lets assume moderate seeing of 2.5 arc sec.
You need to find guide settings that keep movement to within the limits of seeing. ie within 2.5 arc sec
Given that 1 pixel on your guide camera sees 2.68 arc sec of sky if you can keep your guiding to within 1 pixel on PHD you should have satisfactory results.
from your graphs you posted you can see your osciallation index is at 0.41. This is saying there is a 41 % chance that at the next exposure you take on guide cam will likley cause a change direction in RA. Try get this down to around 30%
Your RMS is .29 which is acualy not too bad and most of your data is falling within + or - half a pixel which meats your typical seeing conditions of 2.5 arc sec.
Other than the fact you are getting so much oscialltion from exposure to exposure things ar elooking pretty good. This osciallation wil effectively just blur the image a little and wont be as sharp as you could get. Your stars will be round though but just a little smeared.
Try tame the osciallation by turning off bakclash comp if its on, reducing the agressiveness and max RA. I would try half the max RA first and see how you go. then try reduce egressivenes if this has no results.
Also your minimum move is quite low. You have it set at 0.15 of a pixel. This means you are telling PHD to make an RA drive correction every time the star deviates by more than .15 of a of a pixel. Remember you seeing is only probably about 2 - 3 arc sec. so with this low a number your mount will be chasing the seeing all over the place which can also account for the oscillation. try increase your min move to something like 0.4 instread of .15
In summary:
1. Set your RA Aggressiveness lower to to reduce errors
2. Set your Maximum RA move as low as possible
3. Set minimum move to ignore seeing variation. ( I think pushing this up to .4 or .5 will remove your osicllation)
if you want some theory here is a good arcticle
http://www.wilmslowastro.com/tips/autoguiding.htm
. I did think as well that this thread would be a good resource for newbies to guiding. I am now trying to get my head around the whole 'arcsecond / G-Ratio' thing. It is funny how you can go out and just take an image with the basics and get some results but then when someone mentions the deeper stuff you just have too learn it. It is great that people will go to the trouble to help.
