galactique OAG guiding I get about 580ms: so this is the Calibration Step ?
Just calculate the Calibration Steps to get about 10 to 12 steps (in your case) for PHD2. Check the PHD2 log to see how many steps it took to get 25 pixels worth of movement. You can also just watch it while it is calibrating. Notice that it will move up to 25 pixels and then reverses direction.
BTW, this is why you also want to calibrate near the celestial equator. If you try to calibrate near the poles, it could take half a day's worth of steps to move a star by 25 pixels.
If you find that it takes more than 12 steps to complete 25 pixels, just increase the Calibration step. And vice versa.
Max RA and declination duration are exactly that, the maximum that PHD2 will correct per guide frame. If your camera's FPS is high, you can use a shorter max duration. If your FPS is low (like 0.5 frames per second), you will need to use a longer duration -- but ultimately, it depends on the first derivative of your periodic error curve.
The max durations simply limits how much PHD2 is permitted to apply per guide frame. If you set it too low to match your mount, you will not be able to keep up with the mount errors.
You can set the max pulse duration to 10 seconds, if you like -- this will handle even horrible periodiuc error curves. But with a max value that is unneccessarily large, something like a wind gust or centroid measurement error can cause auto guiding to make very wild back and forth swings, especially when you set a high feedback loop gain (shown as RA and declination "aggr" percentages).
You cannot use someone else's numbers. That is why I ROTFLMAO each time some idiot on Facebook (redundant phrase) asks for someone else's number. It depends on your guide pixel scale, your mount's periodic error and backlash, seeing conditions, etc.
Just remember that PHD2 goes by pixels units in the camera x- and y- directions, while the mount (and guide pulse) works in units of arc-seconds, not pixels, and in the Hour Angle and Declination directions, not camera x and y directions. Once you grok that, it will all come together.
Chen
