I made some new discoveries this morning when creating a new profile to improve my understanding of PHD2.
?
1. It is not possible, when creating a new profile to enter a mount speed less then 0.20 x Sidereal. It's only possible when changing the settings later. (that would be 3.01 arc seconds per second in the Meade Generic driver (if used) before creating a new profile in PHD2 change that in the driver)
?
2. The calibration step size is not only calculated from guidespeed, focal length, and pixel size but also which declination the calibration will be performed, this can be set under Advanced settings.
?
This explains why the calibration step size suddenly changed for me, i was calibrating at a different declination and PHD2 used the pointing information from the Meade driver to use "dec compensation".
?
Since the PHD2 documentation advises against changing guidespeed after creating a new profile, it's probably best to go with 0.20 x Sidereal from the start and leave it.
?
The last calibration that i did, which was Orthogonal, completed in both axis within 8-12 steps and produced good guiding results was done at about 60 AZ and 38 ALT and declination of 46.
?
I had changed guidespeed to 0.18 x Sidereal in PHD2 and as usual 6 arc seconds per second in Servocat Sky, Calibration step size was 4900 ms.
With the new profile i set all the values the same, including declination 46 for the calibration, produced a step size of 4300 ms, since guidespeed had been raised from 0.18 to 0.20 Sidereal.
?
Since the step size is reduced, in order to not slow down the measured guidespeed with 0.20 x Sidereal set in PHD2 it's probably a good idea to use 7 arc seconds per second in ServoCAT sky instead of 6 arc seconds per second, i have changed this in ServoCAT sky.
?
Will be interesting to see next clear night when i will be using the DSC Pro and hopefully do actual capture.
?
?
Here is an extreme crop (to see the stars better) of 180 stacked subs, 20 seconds each processed in Siril on a random part of the sky near Ursa Major, it is from the night when i got around 0.95" RMS guiding with EasyTrack.
?
The stack had a FWHM of 3.4 arc seconds, which is what i get when looping 1 second exposures on a night when seeing is above average from this location.
?
?
Edit (correction): The measured guidespeed will not slow down because of increasing the guidespeed from 0.18 to 0.20 in PHD2, but it will send shorter pulse commands and that will increase the number of steps used during calibration, and to compensate for that it would not hurt to increase the guidespeed in ServoCAT Sky if the number of steps are more than 12.
?
/Gabriel
Gabriel Wiklund