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First Light for BB's

Started by tomhole, 10/27/2004 05:11PM
Posted 10/27/2004 05:11PM | Edited 10/27/2004 05:14PM Opening Post
On a tip from Tom D, I picked up an older Celestron 2x barlow that was really long (5.5"). It kinda screwed onto the nosepiece of the BB and I measured the mag at 2.7x or so. Better than a short barlow was giving me, but not as low as I hoped.

So, the lowest power I can get is 170x with the 24 Pans. The lowest unvignetted power I can get is 240x with the 17 WA's. Not the best options, but at least I get to look at stuff with the BB's.

I pulled the Starmaster out and put the BB's in with the 17mm WA's from Bill. Oila! It focused. First view was the blue and gold double in the northern cross (I'm sure they have a more proper name, but blue and gold are my alma mater's colors). Whoa! It's now a foursome. That's not good. I wiggled the ep's around and got it down to the normal two stars. I suspected the set screw ep holders might cause merging issues and they did. It's easy enough to wiggle the ep and get them to merge. I used the diopter adjusters and as I rotated the right one, the image would merge and unmerge. Looked kinda cool, but not a desirable characteristic in binoviewers. A wiggle of the ep gets them merged again. This phenomenon is to be expected as the set screw pushes the ep against one side of the ep holder thus, uncentering it. As the ep rotates, the center of the focal path rotates around the center of rotation causing the image to unmerge. This is a minor annoyance, but one that new binoviewer folk should be aware of. It will drive you batty if you don't know what is going on.

On to the double double. Wow! Nice split! Then I remembered I was at 240x. I would hope they split nicely there. I put the 24 monocentrics in and still a clean split, as expected. The 24mm ep's were actually 24 Pans but they vignetted down to about 40 deg AFOV or so. That confirms the baffle acting as a field stop theory.

The skies are crystal clear and fairly steady. I anticipate a wonderful evening with the BB's and the eclipse. The 170x I can get with the 24 orthos will be a bummer. I'll have to pull out the Denks for a wider FOV.

No obvious spherical or chromatic aberrations noted during a star test. Not steady enough for a critical test, but at least there wasn't any obvious issues.

Hope everyone else gets to view the eclipse as well.

Clear skies,

Tom