Skywatcher Ultra Wide Angle 9mm
Very good sharpness within 60° apparent field of view, just a little bit worse close to the edge.
x-axis: distance from optical axis in °, y-axis: resolution in arc minutes
Apparent Field of View:
The apparent field of view is approx. 66°.
Very good contrast.
Slight cushion distortion.
Good quality with foldable rubber eye cup.
Large apparent field of view for little money combined with good optical performance. The eyepiece is recommended for use with F/5 or slower optics.