Hi Doug,

Unfortunatelly, there is very cloudy and rainy outside, so I perform my measurements and calculations at home. I MUST be abolutely sure what am I doing before I go outside. That's why I ask for support. All my calculations are made in the Excell, so it's easy to verify it and to change the values quickly.

The EAF has a great feature that it detects a too high torque and it stops then. So I know where is its real zero position and where is its real end position. But I didn't ralize till now that if I moved the tube to the zero position it didn't mean that the count ended with zero, but i.e. 147 instead. Requesting the zero several times moves it slightly, step by step more inwards (76, 42, 1) while I can hear the movement and finally it stops at zero, so I cannot heare the work of the gear. As I wrote earlier, I measured the maximum extrusion using the vernier caliper. I read a rough distance on a scale engraved on the tube after 10,000 steps and based on that I calculated a rough number of steps needed to reach the end point that is around 95 mm. I requested the Ekos to perform the full extrusion and then I found out that I have to add some steps in Ekos/Focuser tab. I set the step as 25 and was adding the value to the calculated number by pressing the "arrow up" button. This way I found earlier that the end position was 25,992 steps.

As I wrote, the EAF stops automaticaly, when the torque is too high. It ends the travel at the end of the toothed treadmill and confirms it by double beep. I positioned the EAF and the focuser at the zero position and requested the Ekos to move it to a 27,000 that is over its capability. Now it stopped at 25,703 steps, maybe there is the backlash invlved. So I repeated the scheme: moved to the zero (it stopped exactly at zero and I can see that there is no gap) and again to the 27,000 - now it stopped at 25,822 steps. And again: 25,805. And once again: 25,803. As you can see, the number of steps is not trustworthy too much, unless you physically force the zero position. Now I can say that all the path takes the EAF ~25,800 steps. It doesn't change too much in the final values: 1 step means 3.658914729 µm while 1 µm means 0.273305085 step.

I assumed 5% of the tolerance and 2 arcsec seeing, but I can assume now the 10%, as you wrote, at least for the beginning. What about the diffraction limit? Can I use the average 130/D value?

I found another my fault in the calculation of the total seeing: I forgot to multuply the diffraction limit by 0.2... Ooops.

Now the NCFZ is 80.18745577 µm. So, even for the full value of the NCFZ the Step Size is 22 steps, because 1 µm meas 0.273305085 step. If I understand it properly, Step Size = NCFZ (or 1/2 NCFZ) * 0.273305085 steps = ~22 (or ~11).

The top row in the picture is the example from the website.

Our calculations are similat till this point. I think we calculate different the Step Size. If I multiply the NCFZ by 3.658914729 that is the movement caused by 1 step expressed in µm, then I get 293.399063 that is very close the result expected by you. But If I following the proprtion below, I get a the value of 22:



Doug, where is the main fault?

Martha

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