Astrophotography Beginners Training - Part 07 - Focusers

[@johnwacker4587]

Thanks Sasha! I’ve enjoyed the base camp series and have learned many helpful tips. I’ve been contemplating the focuser issue as I slowly learn how to get good photos from my Edge HD 9.25 that I bought a year ago. Yep - I need to bite the bullet and get the 2” Esatto.

[@bobbryant4410]

You can also do temperature focus compensation. This allows you to keep your scope in focus during exposures. The Dark Sky Geek created an ASCOM driver for NINA to work with the EAF. He has updated the driver to work with other focusers and temperature probes. I use the EAF and temperature focus compensation in NINA with the "Move Focuser by Temp. "instruction.

[@viewintospace]

Great tip - did not hear of this until now!

[@bobbryant4410]

@@viewintospace Julien, aka “Dark Sky Geek” has two videos on Temperature Focus Compensation. The original video was the development of the ASCOM driver for the ZWO EAF (link: kzbin.info/www/bejne/bGK9fKCqeKeJerc ) and the Second video was for “Any” focuser (kzbin.info/www/bejne/mKq3eGueepqcmqM). In NINA you use the “Move Focuser by Temp.” instruction with Absolute set to OFF. You do need to measure a steps/degree C slope parameter for your system at different times during the year but this can be done with the moon up. I run the Temperature Focus Compensation and Imaging loops in a Parallel Container in NINA. This allows small adjustments to the focus during long exposures. Using this, I have kept my Red Cat 71 with in the Bahtinov critical focus range for over 4 hours with the focuser moving over 200 steps.

[@MakeAMark]

Great set of videos, especially for beginners. One point on the ZWO EAF, it's not advertised it seems, but the EAF has a temperature sensor built in, so you don't need the external thermistor. Also, I find using the ASIAIR to control the EAF more convenient than the external controller, and never use it (assuming you are using the EAF).

[@rainerehlert]

Hi, that is correct but the measured temperature inside the housing is not as accurate as the additional temperature sensor.