Silicon Valley, California
trashbird said:Hi Ed,
I scanned through your fine history, and I can tell you with some certainty that I had the 804 4b2. It was definitely fully-multicoated. Maybe it technically had 14mm of eyerelief, but it still cut off a good 20% of the FOV for me. As Steve Ingrahm pointed out, this still leaves an eyeglasses wearer with a large FOV. I just really like to see the field stop when I look through binocs.
Interesting about the Erfle 5-lens design. I think that Edmund Optics still offers an Erfle-design telescope eyepiece. From what I have read, Erfles have a wide FOV but definitely lose resolution on the outer part of the field. Konigs, I think, are much more prevalent these days in lower-priced wide-field eyepieces. It too apart an inexpensive binoc once -- a Swift Plover, I think -- and saw that the eyepiece was a Konig design. Shockingly, one of the lens elements was plastic! (I really try not to take binoculars apart because I have never put one back together again).
The super-duper wide-field telescope eyepieces, the Naglers, Pan-Optics, etc., have over 8 elements, I think, and may be a variation on the Erfle design. These kind of eyepieces are huge, and would really weigh a binocular down -- not to mention, all those elements really dim the image. However, with new thinner lens designs, and an oversize objective, I am thinking you could build a dream binocular -- say an 8x56 with 8-element Nagler type eyepieces, and 80-degree FOV sharp to the edges, with the brightness of a good 8x42. Porro-design probably, to get the big prisms necessary. And with a reinforced polycarbonate body and modern thin-lens design, it wouldn't weigh much more than the Audubon 804.
At any rate, I'm no engineer. Just a dreamer.
By the way, it was indeed the Swift 825 7x35 roof-prism Audubon that I owned for a short while.
I feel blessed that I don't really have to wear glasses, although the 828 Audubon roof has proven the value of correcting my unbalanced astigmatism by keeping them on. I was out today with the 804R (Type 4b(1)), and again enjoyed the wide FOV and larger 8.5 image with unadorned eyes. The eyecups are wisely engineered to narrow down and hence fit my eye sockets so well there's very little opening for sidelight. In the end, that what turned me off about the 8x30 E2. I couldn't adapt to the very wide eyecups that let in so much sidelight.
My requirements for binoculars are very modest. Of course, they should provide an excellent view and be comfortable to use, but they must also be quality made and good looking. For some reason, brands beginning with "Sw" have these qualities. One of the things I like about 804 Audubons is their rich history and collector potential. I just got an 804 HR/5 ED on eBay, incidentally, which may turn out to be the centerpiece. It's even named after me. :'D