Pentax XW 20mm
Perfect in the center area. Towards the edges still very good.
x-axis: distance from optical axis in °, y-axis: resolution in arc minutes
Apparent Field of View:
The measured apparent field of view is approx. 70°, as given by Pentax.
Very good contrast.
Very slight pincushion distortion.
Comfortable at 20mm eye relief.
That’s nothing we have to report on earnestly for Pentax eyepieces. Look e.g. at the perfect grip coated body, use of high quality materials etc. The cap at the eye lens is removable and releases a thread (43x0.75mm), which can be used for fixation of accessories.
Really a nice wide angle eyepiece. It is a “classic” design, which means
that contrary to the Nagler design the distortion is kept at a minimum.