Some of you may remember from past postings that I have a 90 mm f/9 fluorite refractor, made by Vixen for the Celestron label. It is a fine instrument, easy to set up, and small enough to fit comfortably in the back of my Geo Metro, but I have always been vexed by the fact that it could only accept 1.25-inch eyepiece barrels. I have been well spoiled by low-power wide-field views in binoculars and other telescopes, and missed them in the little refractor.

Recently I spent a lot of time wistfully wondering if maybe I shouldn't get something like a Tele Vue Genesis, or an AstroPhysics Traveler, already equipped with two-inch plumbing; but that seemed such a waste, since the Celestron/Vixen is so comfortable in other ways, and is almost certainly of equal optical quality to any commercial telescope made. Finally, I experienced an attack of common sense and decided to take the Vixen apart, to see if there was any prospect of modifying it to take two-inch eyepieces.

I left my hack saw and plumber's pliers in the tool box this time. Rather, I started gently unscrewing things one at a time, starting at the extreme back end of the telescope. In fact, I have not one but two Celestron/Vixen refractors -- the other is a 102 mm f/9.8 with a conventional doublet objective (no fluorite or whizzy glasses) -- so I disassembled them in parallel, thinking it would be nice to upgrade both.

What I found was, that most of the paraphernalia on the aft end of these refractors unscrews easily. With a handful of black-anodized fittings sitting on the table, I was left staring at silver-metallic finished tubes sticking out of the tailstock castings. These tubes had toothed racks attached, that the pinion gear of the focuser knob engaged, to adjust the focus. The tubes had different diameters on my two refractors -- for the 90 mm, a bit over 5 cm, and for the 102 mm, about 4 cm. The outer end of each tube was threaded internally with 1-mm-pitch threads, to hold one of the black-anodized pieces I had just taken off. Thus it would be possible to have a different threaded fitting, that would screw into the focuser and accept two-inch eyepiece barrels.

What's more, on peering up the tube of the 90 mm, I found that the internal baffles did not vignette any more than the drawtube itself; so that two-inch eyepieces would have most of their field fully illuminated. The field of the 102 mm was restricted rather more, by the focuser tube itself.

After a little nosing through ads and catalogs, I found that Lumicon (of Livermore, California -- they advertise in Sky and Telescope) listed adapter fittings for two-inch eyepieces for various Celestron refractors. Likely one of those was what the 90 mm needed. I called Lumicon, and the person answering the 'phone very kindly went and measured the part in question with a caliper, so that I could compare it with my own measurement of the part I had unscrewed. The fit sounded good, so I ordered one of each, and indeed, one was just right for the 102 mm and the other did indeed fit the 90 mm.

Lumicon's service was fast and polite -- I got the parts in two days.

Meanwhile, I had ordered a two-inch star diagonal from Orion Telescope Center in Santa Cruz, whose service was equally fast and polite -- delivery again took two days. And I had plenty of two-inch eyepieces, from other telescopes, so I was all set.

First light for the modified 90 mm was Saturday 10 February, at Fremont Peak, and wow, what a win! With a 32 mm Erfle (25 x), star images were sharp across the entire field, and the field of view encompassed the entire sword of Orion, showing not only M42 and M43, but also nebulosity around the other sword stars, north and south. Views of other objects were similarly rewarding. Dew and encroaching fog cut short the observing session, but the modification is a complete success, and I am sure the 102 mm will benefit as well. I recommend such an adaptation to any of you who have similar refractors.