Sunday nite was the "maiden voyage" for the Omegon BV with a pair of 23mm Aspherics in the SW180. It was only fitting to invite over a maiden for assistance and a second perspective.
The good news is, using a 1.25" prism diagonal, there was no problem at all coming to focus.
Unfortunately, in other respects, night 1 was a bust. We couldn't get the images to merge. No amount of fiddling helped bring together the two Saturns, one sitting a couple diameters away on top of the other. I punted and contemplated the letter I was going to write to the prior owner of the BV's.
Yesterday, it occured to me to examine the twist-locks more carefully. The collet is fairly narrow, and high in the barrel. I inserted one of the eyepieces, tightened the collet, and felt it hang on the edge of the blasted undercut. Tightening further lifted up one side of the eyepiece before it snugged into place, leaving a tipped eyepiece. That was the cause.
Why don't we boycott all eyepiece manufacturers until they get rid of these cursed things?
So I used some 0.20" wide tape I had laying around, and filled the undercuts. Last night I set up again, sans maiden, to check it out. The images merged.
: The pseudo-stereo effect is compelling, even with a dimmer image. It appears one can use less magnification to get the same perceived detail.
: There is some mild vignetting visible with the 23mm Aspherics. Not objectionable, but noticeable if you look for it. So this FL/AFOV combo represents the outer limit of useable low-magnification and widest FOV possible observing with this setup.
: Eye placement is very finicky.
: Eyepieces with less eye relief and/or good eyecups would help steady the head and let in less ambient light.
: Besides loss of brightness, detaill also suffers through the BVers. This was especially noticed on M22. Comparing mono vs bino with the same eyepiece showed the clear superiority of the monocular with the BV out of the optical chain. This would only be worse with shorter FL eyepieces.
This latter causes me to want to use the BV's at lower magnifications. But we're already at the lower limit with this scope.
So that's where it rests. Yes, it works. Yes, its interesting. But it's not an ideal combo. A scope with half the focal length would deliver a more usable range of magnifications. And bring along its own bag o' worms.
Edited by precaud, 27 August 2019 - 08:57 AM.