Hi Doug,
First of all, thanks for the links and info. I had completely no idea about those concepts (cfz, etc.). In fact I need some more time to digest
but I think that more or less I get the point.
First. The focuser has just arrived. Now I think I misunderstood what the manufacturer said and what is published in their site. The motor is engaged into the low motion knob of the crayford focuser: that's the, I guess, reduction 1:10 gear he meant. So, it is not 16k steps per motor rev, but 1600, and, that's it, 16k steps per revolution of the main focuser knob. I don't know if I'm explaining correctly and, if so, is ok; but I guess. In fact, I've connected the focuser to ekos (perfectly detected, by the way) and a 1600 steps motion order sent to the motor makes it a full (360 degrees) revolution. So, the motor itself has (if I'm not wrong) 1600 steps per full revolution.
Second. According, Doug, to your explanation (thanks again!), my TS102 (f7) refractor has a (more or less) 120um of cfz. I've also measured the drawtube travel per
low focuser knob revolution and after the calculations it results in ~2000um per rev (more or less, the drawtube travels 1cm per 5rev, that makes 2000um per rev). So, 1600/2000 ~ 0.8 counts per micron travel (that is, 1.25um per count). Since I guess we can only send discrete movements (steps, counts) to the motor, every step "action" movement I send to the motor, makes the drawtube travel 1.25um.
Third. As stated, my scope has a ~120um of cfz. As I have understood, the cfz is basically the amount of um I can move the focuser maintaining a sharp image. So, under a perfect focus (that is, I'm just in the middle of the cfz), I can send the motor up to (120/2)/1.25=48 steps and still keep a perfect and sharp image. And this would be the resolution I would expect from the motor and the focuser system. I don't know, however, if consider I would be under or oversampled.
Doug, I would really appreciate your comments about these thoughts. I'm still quite newbie and these terms and concepts are not still completely clear to me and all of this reasoning is, well, just that, reasoning from what I have understand from the info I've read.
Thanks for your help!