I can't answer for Rich, but in my own case, I sold my 20x80's because I didn't see that much of an improvement in the view over the 70mm binos, for the added mass. I would instinctively reach for the 70mm bino almost every time. The 15x70 has a slightly larger exit pupil than the 20x80's, so the added light of the 80mm is negated in practice by it's additional magnification. The only real advantage is increased resolution and magnification... and at these low powers, that's a debateable advantage and object-specific. That said, going to a 25x100mm would be a worthwhile upgrade from a 15x70mm, optically, although the added mass is now much greater and might require a new parallelogram. The one I made for Rich can't handle most 25x100mm. A final note, I find myself actually using my 20x70mm waterproof Bruntons more than my 15x70mm binos most of the time, especially from less-than-dark sites. My 2 cents. On Tue, Mar 9, 2010 at 8:47 AM, <erikhansen@thebluezone.net> wrote:
Rich,
If you are going to put them on a tripod why not replace them with 20x80's? Higher Mag and more light, what is the advantage of 15x70?