4mm orthoscopic by Meade, about 25 years old
Terrible. Bad at the center, it becomes worse to the edges.
x-axis: distance from optical axis in °, y-axis: resolution in arc minutes
Apparent Field of View:
Field of view is 39°.
Very bad, the multi-coating does not help.
Cushion distortion, field curvature and chromatic errors are visible.
Uncomfortable as expected at this short focal length.
Light-weight eyepiece because of aluminum sleeve. Simple, but not bad.
Something for the trash can. However, Meade sold it as a medium-priced eyepiece. Manufacturing of this eyepiece has been stopped years ago – good decision.