Quote:
Originally Posted by AG Hybrid
Due to what Duncan said regarding these eyepieces being designed for telescopes that are no longer in production, they are not all effective in each type of telescopes or a broad range like Naglers are.
If I remember correctly. The 10mm XW and shorter focal lengths were rather well corrected in even sub-F5 reflectors but the 14mm and above induced heavy field curvature. I remember testing this myself a couple years back. I couldn't stand them in my 12" without a coma corrector/field flatterer.
I tested the 14, 20, 30 and 40mm and they were bloody awful without a corrector. And only passable with it. If you want a 14mm with essentially the same ergonomics, fov and image quality as a Pentax get a Delos 14mm instead.
Should be good in your refractor though.
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I used to have the plots that Pentax published, but IIRC the field curvature of the EPs 14+ differs from those <=10mm. This may explain their behaviour in refractors/SCTs vs newts.