Hello h45e,
I think:
Allthough they are named "super plössl" I am quite sure that they are "symmetricals":
2 - 2 like the Plössl, but in the case of the symmetrical two equal Doublet lenses.
These are cheaper in Production that the original Plössl eyepiece design.
Next: The apparent field of view (afov) typically is smaller than indicated in
the catalogue. In a 1,25" eyepieve the maximum field stop diameter is 27mm.
So if you calculate with the arctan formula maximum afov is 37,3!° in a
40mm eyepiece. Add a little bit because of pincushion distortion and you
may reach 40° afov.
Same in a 32mm 1,25" eyepiece where 45,75° ist possible, with pincushion
distortion maybe 48° afov.
The shorter ones are often said to be 52° exepieces, but look more to have
50° afov. Eyerelief is about 2/3 of the focal length.
See the Televue eyepiece specifications for this:
http://www.televue.com/engine/page.asp?ID=144
In a 32mm, 25mm, and 20mm eyerelief is quite nice. But the shorter the
eyepiece focal legth the shorter the eyerelief gets.
I personally can observe well with er down to 10mm and I can accept 7mm er.
In a dobsonian you might consider eyepieces with bigger afov, at least
for higher mags, where the objects speed through the field of view.
But if your Dobs moves verysmooth you can use 50° afov eyepieces
up to about 300x without problems.
I would recommend to use a quality barlow with a longer focal length plössl
rather then a short focal length plössl.
Clear skies, Karsten
