keramos
Based on you previous replies could I request you to kindly elaborate on the tuning of calibration steps i.e. how would one do this in ASIAIR pro? I've had calibration go up to 40 steps definitely West and East don't remember North and South.
Calibration steps is simply the way for PHD2 to discover the scale of the mount's movement when it is told to guide. The Calibration process also finds the actual direction of the movement (the guide camera angle relative to the mount's RA and Declination axes).
To calibrate, PHD2 tries to move the guide star by 25 pixels in multiple steps in the camera's horizontal and vertical directions (and relate it to RA and EDC too). PHD2 averages the movement over these number of steps to average out various noise sources (gear, star centroid, "seeing," etc).
If the Calibration finishes in 6 steps, it is too coarse (i.e., not sufficient points) to make a good estimate of the magnitude and the direction (i.e., the vector) of the movement. On the other hand, if it takes more than 30 steps, you have way more than sufficient points, and you will just be wasting time (otherwise, there is no real harm).
In your case (40 steps), you can save some time in the future by increasing the Calibration Steps parameter in the Guide Settings window by a factor of about 3. This will make each step coarser, and thus finish the 25 pixels in fewer steps.
You might be curious why the step size is specified in milliseconds and not arc second or pixels :-).
Well, the reason is this...
... for mounts that support slewing in RA and DEC, PHD2 uses what is called "pulse guiding." When PHD2 wants to move a guide star by 1 pixel, it turns on slewing in the appropriate direction and then turn it off after N milliseconds later. This is the "pulse" in "pulse guiding." "N" is a function of your mount (and even the latency of the commands from the ASIAIR to the mount).
For most mounts, the timing to determine the duration of the pulse is in PHD2. There are some mounts where you can send a pulse duration command, but the most common mount protocols don't supprt that (I think one day they all will, since it will be more precise).
To figure out how long N needs to be to move 1 pixel, PHD2 needs to measure the mount ("calibrate"). I.e., how many millisconds of N corresponds to 1 pixel.
There is a second parameter that determines how many steps it takes to finish the 25 pixel movement. And that is the "guide rate" of the mount. Now, here is the crazy part... you need to go to Telescope Setup window in ASIAIR to find that.
The even crazier part is that there is a recurring bug that keeps cropping up in versions of ASIAIR where ASIAIR uses the slew rate in the GOTO subwindow as the guide rate, instead of taking the rate from the "guide rate" in the Telescope Setup window. If you find autoguiding for your mount running away at times, try to set the slew rate in the GOTO window to 1x. This will use 1x for guide rate instead of 0.5x, but better than nothing. And of course, recalibrate.
If you scroll close to the bottom of the Telescope Settings (it is really mount settings) window, you will find the guide rate. This is how much the mount moves per second when it is commanded to move. The usual default is 0.5x the Sidereal rate (i.e., if you keep slewing engaged at the guide rate, it moves at half the rate that a star moves across the night sky). If you set this to 0.75x, each second of guide pulse will of course increase the movement by a factor of 1.5. If you change the guide rate, you will also need to go back to adjust the Calibration Steps (and also recalibrate) in the Guide Settings window so that you again have somewhere between about 12 and 25 steps.
So, the short answer to you question is:
1) select a guide rate (0.5x should work fine with most mounts -- I have never come across your mount, though)
2) go to the autoguide window (tap Guide in main window and then tap on the autoguide popup window) and start the calibrating process. If there are insufficent steps, reduce the length of Calibration Steps in the Guide Settings window. If there are too many steps, increate the Calibration steps parameter. Rinse and Repeat step 2 (each time clearing the calibration by clicking on the "i" that is inscribed in a circle in the autoguide window; then clicking on "Clear") until you are happs with the number of steps it takes. Note all the numbers down in your notebook so you won't have to do all this again until you replace your mount.
PHD2 is actually quite simple to use (it was originally named "Push Here, Dummy"). Unfortunately, it is not integrated well in ASIAIR's user interface. To set up guiding, you need to jump between three or four windows!
The good news is that you will eventually get the hang of it, and muscle memory takes over.
Chen