I had a little time this afternoon to play with the bino-viewer. I used a pair of 29mm binocular eyepieces mounted in1.25" barrels and coupled the viewer to my home-made 50mm f/9 refractor. Since it was daylight, I looked at the Wasatch mountains. The view was obviously dimmer with the bino-viewer than without it, but not objectionably so, even with the small aperture. There's lots of light in daytime! The view was inverted but still I could tell that my acuity was better with both eyes than one alone. Even with the inexpensive Kellner eyepieces I was picking out incredible detail on the mountainside. Now I'm eager to observe some planetary detail with both eyes. I have another pair of 23mm remounted binocular eyepieces for this, but I broke down and ordered a pair of the University Optics 20mm, 70-degree wide-scan eyepieces. I'm thinking that with all the internal reflections in the bino-viewer, multi-coatings on the eyepieces couldn't hurt the throughput. The UO eps should be here early next week. A bino-viewer can get expensive just buying eyepiece pairs, that's apparent. Most of my commercial eyepieces are no longer manufacturerd, so I can't just order a second copy of something I already have. My 10" f/5.6 Newtonian has enough in travel to accommodate the binoviewer without using the relay Barlow, so hopefully I can try that combination on the stars sometime this weekend. Stay tuned. On Wed, Apr 9, 2008 at 1:54 PM, Chuck Hards <chuck.hards@gmail.com> wrote:
Can anyone comment on wide-field eyepiece performance in bino-viewers? I'm wondering specifically about noticeable vignetting with AFOV's exceeding 60-degrees.