I’ve been able today to find a way to place the etalon at the right (200mm) distance from the prime focus.

Thanks to the double focuser setup (one before the etalon and one between the etalon and the BF) I’ve been able to also take some comparison shots between different etalon positions.

First of all I have to say that I wasn’t sure if it was the case to process the videos or not as it was cloudy and so even during the recording conditions changed quite often. In any case here are the results:

All the images has been “processed” in the same way.

The longer and shorter exposure recordings has been made after the two with “wrong” etalon position and weather conditions were worst. Despite of that the details are back. Naturally after changing the etalon position I refocused 

So the good news is that I’m done with the new Omni 120 (100mm) setup… I think. The bad news is that weather won’t allow me to take any “serious” shot before at least a couple of days