I'd like a pair of binoculars for hiking. I don't have a specific use other than for looking off of overlooks, at animals, etc. What are the important things to look for in a good set of binoculars? There appears to be a very wide range of price and features to choose from.
I researched this and there are a few factors
Aperture - This is the diameter of the objective (or front) lens and affects the amount of light taken in. Aperture is very important for low light situations. If you plan on using your binoculars near dawn or dusk, or under canopy, then you want a larger aperture. This is the second number used to describe binoculars. So 4x30 binoculars would have a 30mm aperture. Aperture unfortunately tends to linearly correlate with weight.
Magnification - Simple zoom. The first number and indicates the zoom factor. So 4 in our 4x30 example magnifies by 4 times. 9 should be more than sufficient for most hiking. Mountain hikes with long open lookouts may call for more.
Lens Coating - Lens coatings will significantly reduce glare and improve quality. At a minimum you want "Full coated" which means that all lens-air surfaces are coated. Multi-Coating will generally improve glare reduction and is exactly as it sounds... multiple different coatings.
Roof vs. Porro Prism - Roof prism will be smaller, lighter, and more durable, but will provide a smaller field of vision as compared to porro prism. For hiking you want the durability and lightness gained with roof prism.
Water/Fog Proofing - These features are critical if you expect to be in wet or damp environments. I have purchased (and wasted money on) more than one pair of cheap binoculars that did not have this. Waterproofing is usually accomplished with O-Rings, but fog proofing requires that the internal air spaces be filled with inert gas.
Optically, even cheap binoculars are very good these days so unless you need something special I wouldn't use this as a differentiator when looking.
Instead the three I see as most important are size, weight and robustness.
If they are going with you everywhere you need to make sure they will fit in your pack, not be too heavy and be able to take the odd drop, being bashed off trees, getting wet etc.
If you are looking for binoculars suitable for hiking, you should look in the category of 'compact binoculars'. So, what are some of the characteristics of these binoculars?
They should be small and lightweight. Hikers usually carry a lot of weight in their backpack, especially when setting out on a long trek. Heavy binoculars are difficult to store in a backpack since they take up plenty of space. Furthermore, it is not comfortable to carry them strapped around the neck for too long. Compact binoculars boast an ideal weight and size for such occasions (the objective lens measures somewhere between 28 and 36 mm in diameter). They can be easily stored in a backpack and even fit in some bigger pockets. You will not experience any neck tension when wearing them strapped around the neck, even for longer periods of time.
I advise you to get either 8x or 10x magnification binoculars as they are the most popular. Get 10x if you wish to observe more details; get 8x if you wish to have a wider field of view. Keep in mind that the shaking of hands is more noticeable when using 10x magnification binoculars. Binoculars with magnification bigger than 10x should be mounted on a tripod when observing to maintain a steady image.
Roof prisms are more popular than Porro prisms when it comes to binoculars suitable for hiking as roof prism binoculars are not as bulky as the Porro ones. Porro binoculars are known to provide a better light transmission rate than the roof prism ones, but compact binoculars are not designed to be used in the dusk, which is why this feature is irrelevant for such use.
Compact binoculars are not only great for hiking, but also travelling, camping, birdwatching, and many other activities. They can also be used by children because of their small size.
You can buy this type of binoculars for as low as 50 or as high as 2000 EUR. The differences are mostly in the build quality, optical quality, number & quality of accessories provided, country of manufacturing, and the length of the warranty period. We would advise you to spend at least 100 EUR for the binoculars to avoid disappointment.
If you wish to read more about the topic, learn about the features of binoculars in each price class and find out which are the best-performing binoculars in each price class, check out the compact binoculars buying guide on this link: https://www.optics-trade.eu/blog/compact-binoculars-buying-guide/
Note: I have experience in this field as I work at the Optics-Trade webstore.
Let me share my rather limited experience.
A 50BGN ~= $25EUR 12-50x50*:
There are several small loose parts of plastic inside the binoculars. They obscure small parts of the lenses. Not a very big problem, and I accept it for the money.
The 50mm will collect more light through the large input lenses and provide crisper viewing, working well near dawn/dusk. However, the thing weights more than half a kilo - prohibitively heavy for any kind of backpacking.
The variable zoom is useless. Zooming works, but the resolution is limited by the lenses and therefore no additional details appear.
My second binoculars was 12x35, extremely lightweight, waist-mounted. Perfect for hiking, until I sat on it. Lightweight and rugged seem to exclude each other.
My third binoculars is ~100EUR and it seems to be the sweet spot. You can see Jupiter or the Moon's surface!
* The first number (in this case a range from 12 to 50), represents the zoom factor. The second number, in this case 50, represents the diameter of the input lenses in mm