Further tuning the telescope optics: looking for the right distance corrector-sensor (it’s not the Starizona advertized 134.5mm ) and dealing with OAG focus, field, illumination, shadow and also with the new T-Ring filter L-Pro from Optolong.
![](https://i0.wp.com/www.drogenberg.be/wp-content/uploads/2017/07/M57-ISO400-21x120s-C11-Starizona-F72-Nikon-D750-MoonJULY2017.jpg?resize=525%2C351)
Continue reading “Ring Nebula M57 in Lyra – further testing the setup”