My imaging setup is now almost fully automated with the exception of the filter wheel, I have fitted a focuser control stepper motor from Pegasus Astro – This system allows both manual control via a knob on the side of the control box and computer control via USB. The control knob when pushed in allows fine control and simulates the 10/1 fine focus, a green/orange LED indicates either course or fine adjustment – while computer control allows vibration free focusing. I have used the free USB port on the back of the 1600mm Pro camera for connecting the focuser to my laptop. the stepper motor and control box was very easy to install as the adapter plate is universal and I used velcro tape to attach the control box right on top of the motor housing; so it’s all tidy. The stepper motor itself allows incredibly fine control with a step angle of 0.0625° – this means that for one full rotation of the focus knob there are 5760 individual steps, the downloaded software knows the step number and can send the focuser to any defined focus position, this means I can use APT ( Astro Photography Tool ) to automatically focus the telescope with the auto – focus aid, this uses a number based on the FWHM ( Full Width Half Maximum ) of a selected star, basically the lower the number the better your focus. It is also supplied with a temperature sensor so the software can make changes to the focus position as the temperature changes ( metal contracts or expands depending on the temperature and can cause the focus position to change ). The software also allows for setting up filter offsets, some brands of filter are not ‘Parfocal’ so when you change filter you have to refocus slightly, The Baader filters I use are parfocal so this won’t be used but it is a nicely thought out feature.
I tried this out Wednesday night and it worked faultlessly, I imaged the brightest part of the Pelican nebula IC5070 in Cygnus, I only managed to capture 19 frames of 300 seconds each in Ha before the clouds moved in but I processed them anyway, focus looks very good.