Discard 20% of the photons? No I keep all the photons I can :-)
But we will see how I fix that, but it's already good to me. And I haven't got the tilt eliminated yet. Today I made a 80 my shim and installed it. I f also offset the focus position to get rid of a wraparound problem. Jumpning from 65550 to 0.
Have a look at page 8 at bottom:
http://www.astrofriend.eu/astronomy/...pberrypi4.html
/Lars