Quote:
Originally Posted by ausastronomer
Again this is clearly incorrect and it is something you continually harp on and try to push across with zero substantiation.
The only Newtonian specific eyepiece that has ever been designed and built is the "Pretoria" eyepiece, which had an inbuilt coma corrector. This was sold by University Optics and Brandon (Vernonscope) in the 1980's. When Televue released the paracorr in about 1990 the Pretoria eyepiece died out because the paracorr could be used across multiple eyepieces and was more versatile, particularly when they subsequently released the tunable top version of the paracorr.
The facts are that the eyepieces which perform best in fast Newtonians are eyepiece like Naglers, Radians, Ethos and Delos made by Televue, Nikon NAV HW made by Nikon and a few others, none of which are made by companies that make Newtonian telescopes. It just so happens that the only telescopes Nikon and Televue produce are refractors. Do you seriously think that companies like Nikon and Televue are going to design an eyepiece to work well in Newtonian reflectors, but not work well in the telescopes they design and sell? Fact is these eyepieces work equally well in both Newtonians and refractors and just about any other telescope design you care to drop them in.
Unfortunately Alex, to people new to astronomy, you sound like you know what you're talking about when it comes to optics. To people who have been around a while, it's pretty obvious that this isn't the case.
Cheers
John B
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Further reading
https://www.telescope-optics.net/eye...rrations_1.htm
As quoted on Telescope Optics.net and also in Telescope Optics by Rutten and Van Venrooij
"
Most objectives generate curvature concave toward objective, and
most eyepieces nowadays have near flat field, in which case the combined visual field has curvature similar to that of the objective"
These are the reasons these complex eyepieces work equally well in just about all types of telescopes.
Cheers
John B