This post is my opinion only, and is of no scientific value or factual content.
Paul Rini is known for making the inexpensive eyepieces that are optically and mechanically competent. They are assembled from surplus lenses.
I don’t know when Paul Rini started making ep's, or what he is doing now. I remember seeing his ads in the magazines in the late 90's. In 2001 I bought 3 ep's from an east coast dealer. From hearsay it’s probable that this dealer bought Paul’s entire inventory. At the 2004 Delmarva star party I saw the "new" Rini ep's, sold by a rep from Ganymede optics. In early 2005 Paul was an Astromart sponsor. He also had a nice website: "proptics" I believe. It was from his Astromart ad that I purchased some more ep's.
The ep’s come in several varieties: old, new, 1.25”, 2”, and reticle. The old style lacks any signs of mass production. There are numbers hand engraved on the barrels. The 100mm bears the inscription “31644”. The barrels are scuffed and scratched. The lenses have dust, metal bits and the rare, tiny, air bubble. Coatings are minimal and reflections bright. The glass imperfections and dirt are unnoticeable in field use. Some components are held together with adhesive. The bottoms of the 2” barrels are Hoya filter rings. The 100mm has this ring: “Hoya 48mm 85B Japan” Ed Ting reviews some of these, see below for website.
The “new” versions are black anodized aluminum(?) with nice lettering stamped on the barrel. They are in two pieces that unscrew easily. Don’t lose the lenses! The newer versions all exhibit some degree of chromatic aberration not seen in mass-produced ep’s.
The 100mm MPL (modified Plossl?): fov 28deg*. In a 12.5” f/5 dob the secondary mirror is always seen. I viewed the Beehive and Jupiter in the same field in 2003. The targets must be moved halfway from center to be seen. A 3” extender is required to reach focus. Very light weight. Narrow fov and large exit pupil annoying.
The 75mm: fov 36 deg*. Same performance as the 100mm. There are no advantages to using the 100 or 75mm over the 62mm. These ep’s stay in storage.
The 62mm RKE: fov 44 deg*. This is the gem of the Rini ep’s. Very lightweight, low power viewing on the cheap. Pleasing images. Very useful as a “finding” ep. No extender needed to reach focus. Disadvantages: very long eye relief, easy to “blackout”
The 45mm MPL: fov 52deg*. This is where Rini ep’s make their mark. Low power, 2” glass, and relatively flat field, no major distortions. I keep this lightweight ep in the case with the 80mm refractor as a finder ep. New price in 1998: $40.
32mm MPL reticle, 2” barrel fov 56deg**, 14mm eye relief. This oversize ep features the newer style optical and mechanical improvements. The glass is free of debris and imperfections. The barrel is anodized black aluminum, smooth and attractive. Machine stamped “Rini 32mm” The removable reticle is crosshair style with some tick marks and “R L” on either side. The reticle can be sharply focused by unscrewing the eyelens assembly. Focus is set with a nylon setscrew. A very nice ep for aligning the finderscope. Much sharper than the 26mm below.
25mm reticle. A nice lightweight 1.25" ep. I use this one for aligning finderscopes. Similar to the 32mm but smaller. This is the only Rini ep stamped with white letters.
26 and 10mm, 2” barrel MPL. These oversize ep's are nicely machined but optically inferior. The 26 have a large 60 deg fov** but exhibits much edge distortion even in the f/15 scope. The 10mm has only a 45 deg fov** and is optically inferior to any generic 10mm Plossl. They DO make great starparty or public ep’s. No pain felt at $20 each. The chromatic aberration makes the 10mm almost unusable for personal observing.
Of these ep’s I use the 25 reticle and 45MPL the most. The 62 RKE and 32 reticle see some use also. The others are kept as curiosities. Why do I even use them when I have Panoptic and Nagler? They're fun!
Ed Ting review
*Old syle specs
Sky and Telescope Magazine, July 1998, page 131. Advertisement by Paul Rini
**New style specs