I'd been interested in buying low power binos for viewing the structure of the milky way, but I have found almost nothing. There is a 28 degree 2.3x40 TFOV bino available from Japan
http://www.kasai-trading.jp/binoculars.htm, however I think the AFOV is 64.4 degrees (I get this by multiplying 2.3 x 28mm) and I would like more AFOV than this if possible.
What I have been thinking about is making a bino using a Televue Ethos 13mm and a Nikon 35mm F1.8 lens (The Nikon taking the place of a apo scope). Depending on which lens I go with, the Nikon 35mm lens has a > 41 degree full TFOV, although I think 30mm would be optimum.
So as I see it, a 35mm F1.8 lens operates as a 19.44mm (0.7655 inch) F1.8 apochromatic telescope (35 divided by 1.8 and divided by 25.4). With the 13mm Ethos, I should get a 7.2mm Exit pupil and 37.14 degrees TFOV.
With a 30mm F1.8 (0.656 inch), I should get a TFOV of 43 degrees and 2.3x magnification. This would be ideal, except they are no longer making 30mm F1.8 lenses, so the chance of getting two identical ones seems slim.
If the idea seems good I will probably test it on a 50mm F1.8 (Which I already have), which should be 1.09 inch F1.8 scope, and with 13mm Ethos should give a TFOV of 26 degrees at a magnification of 3.83x.
I notice that the field stop of the 13mm Ethos is 22.3mm and the die size of a film lens is 35mm (or with a DX lens around 23.3mm), so I am not sure if this means I would need to baffle it or that I would lose edge illumination or get vignetting.
Has anyone ever tried anything like this before? The one advantage to this design is that these could be binos without prisms, so they would effectively make a Galilean binocular.
I think I can get the T-mount for it from a manufacturer of CCD cameras (it is not the regualr T-Mount), and I think the Ethos 13mm should hopefully get close enough to the lens in the T-mount to focus, but does anyone have any idea if this would work?