TS Ploessl 4mm
Fine for a 4mm eyepiece. Our measurement system is diffraction limited at this focal length to about 1.4 arc minutes.
x-axis: distance from optical axis in °, y-axis: resolution in arc minutes
Apparent Field of View:
The apparent field of view is approx. 46°
Very good for 4mm focal length.
Very short eye relief because of the short focal length. Viewing the complete field of view is not possible without looking into the eyepiece under different angles – or fold the rubber eye cup.
Simple, but not bad. Unfortunately no blackened filter thread.
Great for planetary observations. Just beaten by the Pentax XO – but this is clearly another League in price.