I purchased 3 eyepieces - a 14mm, 40mm and 52mm - from Paul Rini, the New Jersey gentleman offering eyepieces for a phenomenal $17.50 each. The 52mm and 40mm are wonderful for wider fields of view. Large area clusters such as the Pleiades and the Beehive are marvelous in these eyepieces. The stars were sharp, and no chromatic aberration was visible to me, even at the edges. When I tested the eyepieces by viewing the shingles on a neighbor's roof, there was no noticable pincushioning. (For those who don't know, such as myself last week, pincushioning is the name given to the distortion in which horizontal and vertical lines bend toward the middle of the field of view.)
The eye relief on these 2 eyepieces is tremendous! The specs on the website give the eye relief distances as 36mm and 26mm for the 52mm and 40mm eyepieces, respectively. This seems correct, though I haven't measured it. I like these because I can use them with my eyeglasses on! The 52mm ep is a little trickier to use than most, since you need to be 36mm away and on axis with the ep. It's easy to lose the view at first; you really need to be in just the right position to see. At that distance from the ep, a lot of the light from your surroundings can make its way into your eye. I'm considering adding rubber eyecups to these 2 eps.
The website lists the eyepieces as modified Plossls (MPL), but the 52mm is labeled RKE. This is indicative of a "David Rank-modified Kellner for Edmund" eyepiece. The Astronomics website says "[RKE's] are computer-optimized ... for low to medium power use on telescopes with focal ratios down to f/4. Like all Kellners, however, they still perform best with scopes having focal ratios above f/6, and preferably above f/8." This eyepiece seems to work very well in the ETX at f/13.9.
The 14mm is a bit different than the other eyepieces. It exhibited a bit of pincushioning in my "shingle test", and in viewing Saturn, showed some chromatic aberration at the edges. It is also a touch less sharp than the other eyepieces. This is still an excellent eyepiece for the money, though!
At $17.50 each, all 3 eyepieces were better than I expected. The 40mm ep is one that no ETX owner should be without, and experimentation with the others is encouraged. With the ability to get 3 or 4 Rini eyepieces for the price of one Meade 4000 series eyepiece, there's nothing to lose!
Paul Rini's website no longer works. Here is the latest contact
information I have for him:
Maple Shade, NJ 08052-0224
Mon-Fri 8:00-11:00 AM and 6:00-11:00PM