Jason Magna Vue
The Magna Vue was an early line of binoculars from Jason with both a wide field of view and long eye relief, a rare combination for commercial models. These are very comfortable binoculars to look through, although the deep eyecups should be removed when using glasses. Unfortunately, both of my samples have low index prisms.
Magna Vue 7x50, No. 962018
Mfr: J-B22, J-E29
Date: circa early 1960's
AFOV: ~65 degrees
TFOV: ~9.2 degrees, 484 feet at 1000 yards
Eye Relief: ~22mm
Prisms: low index
This binocular appears to be from the early period of J- markings when the maker put the J-B number on the prism cover (the J-E marking is on the hinge support). It is a delight to use with its excellent eye relief. The image is fairly well corrected across the field, though the edge is soft as is expected in a wide angle design. There is some light leakage from the prisms and other spots. I partially disassembled the eyepiece and it appears to be a Plossl design (2-2 configuration).
Magna Vue 8x50, No. 813716
Mfr: No J- markings, probably same as 7x50
Date: circa late 1950's
AFOV: ~68 degrees
TFOV: ~8.5 degrees, 446 feet at 1000 yards
Eye Relief: ~19mm
Prisms: low index
There are no J- markings on this binocular, so it is probably from before 1960. Its construction is practically the same as the 7x50. However, the eyepiece is an Erfle type with a 2-1-2 configuration (or what is sometimes called "Super Plossl" today), with a 30mm diameter element closest to the eye. The extra 8x magnification is very noticeable in comparison to the 7x50 and I prefer it for most astronomical viewing, with the additional image scale and background darkening. It is too bad that more 8x50 binoculars have not been made. I consider 8x to be an ideal compromise between 7x and the image unsteadiness of 10x. As with the 7x50, there is some extraneous light and prism leakage. Other than that, I find the image to be very pleasing.