APM 80mm F/6 Triplet and 10mm Radian tested on proper mount

[michael.h.f.wilkinson]

Today I finally got round to putting my 80mm on a solid mount, to put it through its paces at higher magnifications. I simply attached it to my Vixen Great Polaris mount, and after removing one of the two counterweights got the whole thing nicely balanced. Though it is a bit hazy this evening, I got some really nice views of the crescent moon, at first with the 22mm, but then with my new Radian 10mm, yielding 48x magnification. The view was very sharp indeed, no colour fringes anywhere, and as contrasty as could be expected with the slight haze. I then threw the 3x TeleXtender into the mix, to reach 146x magnification. The atmosphere now seemed to be slightly unsteady, but the mount was solid as a rock. The image was still nice and sharp. Detail around crater Theophilus standing out nicely. The top of the central mount was neatly illuminated. I tried the 2x TeleXtender with the 8mm Radian at 120x, with similar views, but a bit crisper, and with the 10mm Radian at 96x which still showed all the detail, but with slightly more contrast, due to increased light levels.

It is immediately tempting to compare the view to those with the C8, but that comparison is not really fair. The C8 at 50x magnification with the Paragon (1.38 deg FOV) is just mind-blowing, because the view is sharper, and much brighter. At 143x with the 14mm UWA I still have the entire moon in the FOV in the C8, it clearly shows more detail, and the image is considerably brighter. Only in terms of contrast does the APO have the edge.

I gave Jupiter a quick glance at 48x with the Radian 10mm, but atmospheric refraction turned it into a little rainbow, so I left it at that.

Returning to the 22mm I gave the Pleiades a quick look. Really nice view with stars sharp from edge to edge. The focuser of the scope is just a joy to work with. I just relax my eyes, tweak the fine control and enjoy the razor-sharp result. Finished off with the double cluster, framed neatly in the FOV. There was a bit too much background haze, and the football field has its floodlights on, so the view was not perfect, but the optical quality is just great. The Radians seem to fare very well in this faster scope, producing sharp, contrasty images from edge to edge. They are also very comfortable to use. The two Radians are not parfocal, BTW.

This run clearly shows the little scope deserves a first-rate mount. Now to get one that travels well.