Telescope Reviews: Baader Classic Ortho

OK, I can't take the pressure any more. I'll come clean with my comparo.

The same night I took out my 90mm Mak and the Q-Turret, of course I had four eyepieces along with me, too. They were the BGO 9, SF (Sheldon Faworski) Ortho 10.5, TV Plossl 11 ... and the BCO 10. According to Clear Sky Chart, the seeing was supposed to be "poor," but I think it was better than that. I'd give it about a 3.5 to 4 out of five. The Moon was one day past first quarter.

Except for the BGO 9, the eyepieces were nearly parfocal. I just needed to move two of them up a little in the focuser holders. Then I could switch the Q-Turret quickly and easily among the BCO 10, SF 10.5 and TV Plossl 11. For the BGO 9, I had to use the focus knob on the 90mm Mak.

The magnifications and exit pupils were:

BGO 9 _____ 167x _____ 0.9mm
BCO 10 ____ 150x _____ 1.0mm
SF 10.5 ____ 143x _____ 1.1mm
TV 11 ______ 136x _____ 1.1mm

First I observed the Moon. All four eyepieces gave a comparable view of the lunar surface. I couldn't find any detail that was visible in any of the four eyepieces that wasn't visible in all four. But the TV Plossl 11 gave me the most pleasing presentation. There was something about it that was just more "contrasty."

I looked for some detail that was seen in the TeleVue that I couldn't see in any of the others, but there wasn't any. Somehow, though, the TV Plossl presented an image that was "contrastier" which gave the illusion perhaps of a sharper image. This was especially noticeable on the maria, away from the terminator. Maybe this was due to the "coffee" tone?

The 11mm is one of the newer TV Plossls, with the undercut. I was surprised, because my previous experience binoviewing the Moon in my 10" and 8" Dobs with a pair of new TV Plossl 25mm (at 12mm or shorter due to an OCA) was nothing special. In those cases, I preferred pairs of BGO's or even SA LERs. Maybe I should try binoviewing the Moon with my shorter focal length TV Plossls?

Next I turned to Jupiter. All four Galilean moons were lined up to the west of the planet. They were about equally spaced. A nice show. I could tell they were not stars, though they were not quite resolved as disks. The NEB and SEB were obvious and easy. The polar regions were also not difficult. When the seeing cleared a bit, I could begin to make out a few more bands. Switching among the eyepieces, I could discern no variation in the level of detail or perceived contrast. Especially when switching quickly among the three "parfocal" eyepieces, no differences were seen in the images. Even the magnifications were close enough that the size of the disk did not change appreciably.

I wouldn't want to make a final judgment based on this comparo. Smaller apertures often cannot show the subtle differences among eyepieces that larger ones can. And the seeing was only mediocre. A better comparo would be in a larger aperture during better seeing. But that night was cold and I knew the seeing wasn't the best. That's why I took out the 90mm, and not my 8" or 10" Dob.

Maybe next time.

Mike