Art. –Nr. RE-SWA-20
Super Wide Angle 20mm
Sharpness:
Very good at the center, but drops towards the edges
x-axis: distance from optical
axis in °, y-axis: resolution in arc minutes
Apparent Field of View:
Our measurement gives 67° - close to the manufacturer data.
Contrast:
Very good.
Aberration:
Slight cushion distortion as well as field curvature.
Eye Relief:
Eye relief is close to be comfortable, but you can not wear eye glasses.
Mechanical Quality:
Good quality with rubber eye guard, grip coated body. Fully multicoated
and well blackened inside.
Summary:
You can not use the full apparent field of view in good optical quality,
and really not recommended for F/5 or F/4. However, as the field is much larger
than for Plossl eyepieces, there is an advantage at a more or less equal price.
Edge quality is enhanced remarkably when combining this eyepiece with a Barlow
lens.