Vortex is famous for their warranty being great. Because they get a lot of practice at replacing defective crap. Paint me as not a Vortex fan. But I'm an optics snob (the binoculars I always carry are Swarovski EL). Vortex high end stuff really isn't bad, but we're talking well over a kilobuck, way out of your budget. And in that price range, I'd never consider Vortex as you can get the actually legitimate good stuff for that much money. Their budget crap is just budget crap. No better or worse than dozens of other cheap brands. They do have that famous warranty though...
Optics are a get what you pay for game. The curve gets steep and the returns diminish rapidly once you start looking at over about fifteen hundred bucks. But you can't get really good stuff for $400, either. Decent, but not really good and definitely not great. Decent is probably all you'll ever need though. It's not until you start spending days at a time with binoculars growing out of your forehead that the benefits of really good glass start to show strong. For occasional, casual use, you'll find something to be happy with in that range.
Magnification is pretty straightforward. The 7x, or 8x or 10x simply means that a distant object will appear 7 times or 8 times or 10 times closer. Novices usually get too much magnification, which is more difficult to hand hold steady and actually ends up causing more eye strain and a less clear view than a lower magnification. I personally like 8x. I can only use 10x for short stints. You might be fine with 10x though, as it doesn't sound like you intend to spend long hours behind the glass.
The second number is the objective lens diameter. Common designations include 7x35, 8x40, 10x50 etc. An 8x40 means 8x magnification with a 40mm objective lens.
The objective size matters, with bigger being better for optical quality and low light brightness. The objective diameter divided by the magnification is what is known as the exit pupil. An exit pupil as large or larger than your actual pupil dilation will provide all the brightness available. An exit pupil smaller than the actual dilation of your eye will appear less bright.
The average human pupil will be around 5mm in dim light. Everyone is different though and again, size does matter. I'm cursed with small pupils, they don't dilate to 5 until it's dark. The upside, is that optics that might appear kind of dim to someone else, look normal to me, because my pupils don't dilate that large.
So, you want to avoid small exit pupils as found on compact binoculars like 8x20. As a general rule of thumb, going for an exit pupil of 5 should be all you can really use under normal viewing conditions.
So, all that said, my recommendation is a 7x35 or an 8x40.
You'll have a choice in prism style. Porro prism vs. roof prism. Porro prism are the old fashioned type with offset barrels. Roof prisms are more compact and lightweight. Everybody wants roof prism. But, the old porro design is optically more efficient and considerably less expensive to manufacture at equal optical quality. So, bang for the buck, porro prism still rules. And in the $300 - $400 range, that will be noticeable. I'd get porro prism, at that price range, unless you really just can't stand the size and shape.
And, speaking of size and shape... That matters a LOT. A whole heckuva lot. Do NOT buy binoculars without handling them in person first. Ergos make a huge difference in the real world usability of binoculars. And it comes down to hand size, the shape of your face and personal preference. I highly, highly recommend you go to Cabela's or Sportsmans and handle all the candidates in person in your price range before deciding.
But I'd be looking for a 7x35 or 8x40 porro prism in your budget range. Really, you can still get some better than decent glass at that price if a porro will work for you. Roof prisms in that price range, meh, none of them impress me at all.
- DAA
