The Clave' plossl are considered the only true plossl because the original optical design of a plossl was a couple of different doublet (asymmetric doublet). A more economical design of plossl is the common symmetrical design where the two doublet are the same, but obviously nothing to do with asymmetrical design. The Clave' eyepiece remain the best of best with some other eyepiece like Zeiss Abbe II, without distinction of planetary or deep sky eyepiece: this is a non-sense. If an eyepiece has a superior optical correction with a very small number of optical surfaces like Clave' or Zeiss it means it transmits much more light then a five or eight elements eyepiece despite of "fantasy" of some observer: number of surfaces x % of light absorption, it is very easy to understand. If you have a very large field eyepiece you have to correct the field with a lot of optics: you will lose light! A like this eyepiece is like a big TV but it will eat light and optical correction. Simple design and high quality glasses and coating is the Clave' secret.
