I've been looking at the Leica Ultravid in 7x42 and 8x42. Can't go wrong with either, but wondering what everyone here thinks in the trade off between brightness and 1 more power of magnification. Is there a measurable difference between the two?

While I have no experience with the Leica, I can tell you I simply cannot tell the difference in 7 or 8 power in Swarovski binoculars.

My dad owns a set of SLC Swarovski binoculars in 8X30. I own a set of the same glasses in 7X30 power. I simply cannot tell the difference in the two binoculars!

I bought the 7 power glass because I got a hell of a deal on them through Cabela's at that time.

In a roof prisim bin a 7x will have one or two LESS glass elements than an 8x. Granted, in a top bin like the Ultravid it's not a big deal, but less glass for light to go through is always better. Also, the 7x has a larger exit pupil which contributes to less eye strain while moving your eye around the image in the bin.

I think the 7x42 Ultravid offers a very slightly better image than the 8x42. The difference is very minor and, for my eyes, I think these are the two finest bin's made, period.