I learned a lot when I began shopping for binoculars about 7-8 years ago. I depended upon binoculars a lot because I was doing my deer hunting exclusively with an open sighted flintlock, in all seasons. I loved my little Nikon 7 x 20 compacts, because they were light as a feather. But when I needed them the most... near dawn and dusk, they didn't transmit enough light to make out bucks in the thickets. I had a nice pair of porro prism 7 x 35 Sans & Streiffe model 702's that utilized some superb Japanese glass, but I dropped them out of a tree stand and knocked them out of collimation. My Pentax 7 x 50's are decent, but not great, and way too heavy and bulky for still hunting.
I started out looking at Zeiss, Swarovski, and Leica binoculars that met my criteria. I didn't want over 7x since any hand shake becomes more apparent at higher power. I wanted at least a 5 mm exit pupil since that was the most that 50 year old eyes could utilize anyway, and very important was my self imposed weight limitation of no more than 22 oz., since I tend to do a lot of walking, probably more than I should. In fact, I pushed an 8 point buck to another hunter during a move to another stand on Monday. I soon found that the three ultra premium brands I mentioned were all much heavier in models that met my other criteria.
I continued to do research and comparison shop. I pored over reviews in birding magazines since bird watchers are known for demanding the absolute best in resolution and optics. I actually bought a pair of 8 x 40 Nikons that were highly rated. When I received them, it was a dreary rainy evening. I unpacked them and looked at some distant objects in the waning light. They seemed good until I grabbed those damaged 1960's vintage Sans & Streiffe 7 x 35's. When I torqued the mis-aligned barrels to bring the images back together, I was shocked to find that they were clearer, sharper, and brighter than my brand new Nikons. What really pissed me off was seeing that the Nikons were made in China. I sent the Nikons back and kept shopping. Long story short, I ended up buying a pair of the unfortunately now discontinued Swift Eaglet 825R 7 x 42's. They were, and still are outstanding, with low ED Japanese lenses and prisms. In side by side comparisons to Zeiss and Leica's under the same low light conditions, looking into woods and brush, looking at distant numbers or letters on road signs and mail boxes, looking at roofing slates on a distant barn, they are 98-99% as good for light transmission, clarity, pincushion distortion, edge to edge sharpness, etc., and they cost half as much. But even better to me was that their overall quality came in at 10 - 12 oz. lighter than their much more expensive competition. They weigh 21 oz.
So it boils down to compromise. The absolute very best optics glass in the world unfortunately comes in some heavy packages. That's fine if you sit in a stand all day. I chose to sacrifice perhaps 1% on optical quality in order to not feel like I've carried a brick around my neck all day. There are some real sleepers out there if you shop and compare. That's the hardest part, because it is extremely hard to make a valid comparison unless you can look through several different brands and models under the exact same conditions, at the same time. And looking out the window or door of an optics shop at noon on a clear day won't tell you a damn thing about how they will perform at dusk on an overcast December day in the brush.
