Quote:
Originally Posted by Don Pensack
ES 9x100=9 elements in 6 groups
ES 9x120=12 elements in 6 groups
Pentax XW = 6 to 8 elements depending on focal length (40mm 6 elements in 4 groups, 3.5mm 8 elements in 5 groups, 7mm 8 elements in 6 groups)
Delos = 8 elements in middle focal lengths, unknown at the ends
Ethos = 8 to 10 elements depending on focal length
All these eyepieces have about the same number of air-to-glass surfaces, so what's the difference?
Coatings. Pentax and TeleVue use very sophisticated coatings and also multi-coat the cemented surfaces.
Polish. Higher polish results in less light scatter
Design parameters. Different eyepieces have different spot sizes and this results in superior focus to fainter stars.
|
There we go. I knew I was on the right track.
