Greetings!
If you are after light weight, I would HIGHLY recommend that you pick a 25mm or 32mm objective lens. The 42mm and 50mm binoculars will REALLY let you know they've been there after you carry them around for a day... your neck with thank you for going 25 or 32.
I can personally recommend the following models without reservation, depending on your price range and the quality you are after:
Leica Trinovid BN 8x32 (Approx. $900)
Nikon HG (Venturer LX) 8x32 (Approx. $500)
Nikon HGL (Venturer LXL) 8x32 (Approx. $800) [A few ounces lighter, and you pay for it!]
Leica Ultravid 10x25 (Approx. $550)
Nikon HG (Venturer LX) 10x25 (Approx. $450)
Kahles 8x32 (Approx. $600)
Minox 8x32 (Approx. $500)
Brunton Echo 8x32 (Approx. $225)
All of the above binoculars are truly excellent optically, waterproof, fogproof, and quite rugged (ESPECIALLY the Leica Trinovids). If I were going for a lightweight binocular for hunting, my first choice would be the Kahles 8x32, you just get more bang for your $$$ with that brand... although the Minox 8x32 are very close (not quite as good in low light) for another $100 less. The 10x25 models are GREAT for daylight use, but suffer quite a bit in dark forested areas or low light around dusk. If you are on a tight budget, the Brunton Echo 8x32 is a VASTLY underrated piece of optics - easily within 10% performance-wise of the other 8x32 models mentioned, at under 1/2 the cost. For the ultimate in rugged hard-use, the Leica Trinovid has NEVER been beat by any binocular model that I've ever seen... those things are TANKS (and cost about what a tank costs too!).
Finally, the Nikon HG and HGL series have the most vivid, contrasty and colorful image I've ever seen in a pair of binoculars along with great edge-to-edge sharpness, but you pay for it in extra weight and lower brightness (especially under low-light conditions).
Good luck with your purchase, I hope you enjoy what you eventually decide to buy!
Best wishes,
Bawko