Pentax XW 5mm
Perfect up to the edge. At 5mm it is simply not possible to get a better result.
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. 67°, close to the 70° given by Pentax.
For a 5mm eyepiece containing 8 lenses: outstanding! Compared to the 5.2mm ED by Soligor contrast is really better and just beaten by the 5.1mm XO.
Slight cushion 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.