Hi Andrew,
Here are my settings using an Edge 9.25 with no reducer, Feather/Micro Touch and a modded 6D. Second pic is the nice v - curve that results. 300 for backlash compensation is good, and you are correct that the direction is in. These settings give me excellent, repeatable results. Let me know if I can help if you have any issues, since my setup is very similar. Note that you no longer need to disable smart focus with the newest focus routine in SGP.
To initially set it up and find your step size, start by getting excellent focus using a Bahtinov mask or other method, then try to run the auto focus. With my setup, I find that the tops of the v curve, where the focus is the worst, give me around 5.5 HFR when the seeing is such that the best focus is around 2.0. If the v curve is not steep enough to get you in this general area, try to increase the step size. If your step size is such that the tops of your v curve are much above about 5.5 or 6 HFR (assuming that the seeing is such that best focus that night is around 2.0 HFR), try reducing the step size until you are in that area. In general, you are shooting to have the HFR at the tops of the v curve around 2.5 to 3 times what it is at perfect focus. So just adjust your step size until you achieve this. You can have the worst focus positions of the v curve showing small donuts and it should still find focus unless the donuts are really big.
Once you have the right step size, unless there has been a really drastic temperature change from the last time it was focused you will not likely need the Bahtinov mask to start the night. You can just run the auto focus routine.
And I promise once you have this set up properly, you will actually enjoy watching it go through its routine as it brings you to perfect focus every time. I use temperature compensation, set at -6 steps per degree C. This lets me image for hours without having to stop and do an auto focus run while still maintaining perfect focus.
Dean
