Mirko,
Thanks mate!
I find Ha solar scope users have difficulty with two things....focus and etalon tuning.
A single etalon system (PST, Solarmax, Lunt) will always show the spiculation layer (between the "white light" Photosphere and the Ha Chromosphere) at the solar edge....this sometimes confuses the novice when trying to find best focus.
This is best resolved by using a feature (if any!!) on the surface, or a brighter prominence as a focus point. A motorised focuser certainly helps. Practise....
Tuning: Red wing/ On band/ Blue wing???? Doppler shift???
All tilt tuners are set towards the Red wing when closed...
Opening the tilt adjuster moves the central wavelength from the Red wing across the Ha ("On-band") towards the Blue wing - and and eventually to the background continuum.
When "On-band" the image is brightest and the contrast greatest.
One of the best and "Wow" images I've seen for a while was one uploaded by Josef in 2016 - he clearly shows the transition from White light features to Chromospheric features while tuning from the Blue to the Red
Amazing stuff!!!
https://www.dropbox.com/s/im0ujj8fmz..._edge.gif?dl=0
Ken