by Paul LeFevre
Last Saturday, with a brand new TV-85 refractor fresh out of the box, I gave it a quick test run on some similar objects. As you mentioned, Castor was an easy split -- I used a 4mm Vixen Lanthanum EP (150X) and had a great view of the pair. Comparing it to the view through my 10" LX200 (which has fine optics for a commercial SCT), I noticed a much cleaner split...the SCT showed clearly it was a double (18mm Radian, 138X), but the two blurred together somewhat. The TV-85 split them cleanly, and I had much more of a sense of the color of the pair with the refractor (whitish-blue and whitish-yellow). It was tough to see any color in the SCT, as the stars were merging together a bit and the diffraction rings were washing over each other.
I repeated the experiment on Procyon as well. The little TV-85 shined again, giving me an obvious split at 210X (8mm Radian with a 2.8X Klee barlow). I pushed the power up in the SCT (4mm Vixen Lanthanum, 625X), but the seeing wasn't supporting that much power, and all I had was mush. Dropping back to 312X (8mm Radian) in the SCT, I thought I detected a hint of the companion, but it was never as distinct as with the TeleVue.
The little 85mm APO doesn't have the aperture of your AP-10, but at least now I understand why these little refractors cost so much...the views are worth it! Good stuff. Takes good images, too (only got one shot that night, http://www.slip.net/~lefevre/mx7c/m42tv85.jpg).
