Are Radians and Pentax XLs ALWAYS first in performance

It would be valuable to note what focal ratio telescope(s) [all?] your evaluations apply to.

Some planetary observers rate "classic" eyepiece types, such as UO orthos, Brandons, and TV Plossls, as producing superior contrast images of planets, compared to eyepieces with more optical elements, such as Radians.

Personally, I find TMB Super Monocentrics to be the "ultimate" planetary eyepiece, as long as the telescope is f/12 or slower. With f/7 or faster telescopes, TMB/SMs have unacceptable residual spherical aberration and limited field of good definition.

On Yahoo groups, the TEC group, Yuri Petrunin has a very insightful evaluation of eyepieces. The Pentax XLs rate very highly. Presumably on f/7 apos.

I have two Pentax XL eyepieces with my 5.9 FR dob. The Pentax XL 10.5 is my primary planetary eyepiece. It performs very well for this purpose. I have no tracking, so it is very important to me to have a clear image of the disk from one side of the FOV to another. There is no distortion whatsoever. I've had the chance to look through a Pentax XW 10.5 in my scope and it performed just as well with the slightly larger FOV.

I also have an XL 40mm but not used for planetary viewing much. It performs well under dark skies. Not so great under light polluted skies. A little bit of image distortion around the outside 5 to 10% of the FOV.

I hope this helps.

Jim

I sold all my Radians after comparing them head to head one night with supermonos. (They were my planetary ep before.)

"first in performance"?? Heck, I dunno. I have neither the time, money nor inclination to test every possible eyepiece design to determine what's the absolute best. I rely heavily on the forums and reviews for insight as to what might be worth trying. Once I've found something I like, the search stops. Viewing comfort and decent eyerelief count almost as much as sharp, detailed images. e.p.s that are prone to blackouts and kidney beaning don't stay long.

That said, my Pentax XL 7mm and 10.5 mm are two favorites as is my XL 40mm...I have no other XLs. Primary usage is in f8 and f8.6 APO refractors and also an f6 dob. Have thought about looking for a 5mm XL, but the search stopped at a very good 5mm Tak LE.

Other favorites in these scopes: 9mm and 12mm UO orthos, 19mm Panoptic, and a very sharp Meade 26mm Plossl.

I'm easy to please.
Bob

The Pentax XLs and newer XWs are nice eyepieces. They are, however, subject to glare from bright objects just outside the field. Usually, this is not an issue, but it has caused me to change eyepieces when observing near the Moon or an occultation on the dark limb of the Moon.

Clear skies, Alan