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Binoculars are standard equipment for a myrid of activities such as birdwatching, hunting, wildlife viewing, sporting events, and more. What does all the terminology mean and what do you really need in a binocular? This article will help you learn more about binocular features and aid in you making an educated purchase.

 

binocular comparison

 

Porro Prism binocular

 

Roof Prism binocular

 

binocular display

 

binocular eye relief

Binocular eye relief is important if you wear eye glasses. Having a longer eye relief also makes it more comfortable viewing if you don't wear glasses. Eye relief refers to the distance from the eyepiece where the image will remain in focus.

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How to choose binoculars

Making a selection from the wide array of binoculars available can be daunting. There are a lot of manufactures and lots of models from each manufacturer. This article will help you make a binocular buying decision by explaining some terminology and features. Then, comparing models will be easier. Research the binocular features online from the manufacturer information. If you can, visit a larger hunting store, like Cabela's or Bass Pro Shops, or a specialized birding store to compare some different models and price ranges.

How much do you want or need to spend

Binoculars range in price from 10 to 1000's of dollars. What is the big difference between them you may ask? There is quite a bit of difference in quality between the price ranges. More information about the features are below. The typical price range for decent quality binoculars is $100-$400. Anything lower than around $80 is more of a toy than something you will be happy with. Binoculars in the medium price range have sharp, quality optics. When you start getting above the $400 range, things get a little murky. The question is how good is good enough? Most people can't discern the difference between a mid priced optics and super expensive optics, so why would you need them? Your best bet is to go to a store that carries a large selection and do an actual comparison for your eyes. Swarovski is a great name, but I have seen some where I can not discern any difference from a mid priced Eagle, Bushnell, or Vortex binocular. Another thing to think about is that you are carrying an expensive piece around your neck. If you drop or loose your binoculars, how much money are you going to be out to replace it?

Roof or Porro Prism binocular body types

There are two major body styles that are named after the prism they use inside the binocular. The porro prisms are larger, easier to manufacturer, and cause the weight of binocular to be heavier than a roof prism design. Porro prisms, being heavier, also tend to be knocked out of alignment easier than the more rugged roof prism design. There isn't a real difference in quality between the two body types, either can be made of similar quality. It is more about weight and portability. Roof prism binoculars are more compact, lighter, and can be sealed better from dust and water.

How much binocular magnification

There are some balances to be made for your intended use, skills, and the power of the binocular you choose. Most binoculars range from 7 to 10 power. In general the lower the power, the greater the field of view and ease of holding them steady. A binocular with 7 power would be good if you have trouble following or finding your subject, like a bird flying from branch to branch, or if your hands are a little on the shaky side. An 8 power is a balance between a 7 and 10 power, while it will give better magnification, it will still have a reasonable field of view, and may be the limit for those who don't have a steady hand. More experienced birdwatchers can use 10 power binoculars, since they are skilled in finding birds with binoculars, and need the greater magnification to discern fine details for bird identification. For glassing, a term often used describing a hunter scanning long distances for game, an 8 to 10 power binocular would be best for viewing long distances. I would stay away from “zoom” type binoculars, as the mechanisms to achieve the zooming degrades the overall quality of focusing and typically narrows the field of view greatly.

Binocular objective lens sizing

The objective lens of a binocular is on the opposite end that you view through. In general the larger the size, the greater amount of light is gathered. A 50mm lens allows about 42% more light, than a 42mm lens, to reach your eye. This becomes important when viewing in overcast, dim, or night conditions. That being said, most of the roof prism body types use 42mm lenses, but they will out perform a cheaper 50mm lens due to quality coatings, and better prism material. So, you can not judge by size alone. Common power/objective lens sizes are 7x35, 7x50, 8x42, 10x42, 10x50. Anything under 35mm should be considered only for pocket binoculars. In my opinion, pocket-type binoculars usually don't work much better than your eyes and have poor light gathering.

Binocular prism glass and coatings

First, there are two grades of glass used for binocular prisms, Bk7 and Bak4. Only inexpensive binoculars will use Bk7 prisms, as it is a less expensive material. Good quality binoculars use Bak4 glass, as it is a higher grade of glass that produces better light transmission and better images. If the manufacturer doesn't mention which type of glass used, it should be assumed it is Bk7. Better quality binoculars apply a coating to color phase correct the prisms to enhance the accuracy of color alignment that reaches the eye, called PC or Phase Correction. I have noticed binoculars with phase corrected prisms to have better contrast and perceived image crispness. Some manufacturers will even coat the prisms with silver for better light reflection, but compare them with others before buying into marketing.

Binocular lens coatings

Manufacturers have many names for coatings and you have to be careful with the exact wording to know what you are getting. Lens coatings increase the amount of light that is transmitted through the glass by reducing light reflections. There can be single coatings or multiple coatings. Fully Coated (FC) means only one coating is applied to often only one side of the objective lens. This is the least expensive coating. Next, there is Multi-Coated (MC) which amounts to more than one layer of coatings applied to usually only the objective lens. Most good quality binoculars are Fully Multi-Coated (FMC), meaning all the lens are coated with a number of layers of anti-reflection coatings, thereby increasing the amount of light to your eyes. Coatings can make a significant difference in how brilliant the binoculars are able to pull in a subject under dim conditions and overall make viewing much better. Many manufacturers have developed their own coatings to enhance the light transmission of their binoculars. Some manufacturers are also using better quality lens glass, like Extra Low Dispersion (ED) and Fluoride containing glass, which allows for thinner glass, better light transmission, and lighter weight. But, you will have to compare those expensive lenses to a mid-priced binocular to see if they make a difference to your eyes.

Minimum Focus

Expensive binoculars make a big deal out of focusing within 4 feet, but how often can't you see something 4 feet away? Maybe if you are studying insects, that is important, but a reasonable good minimum focus would be around 10-14 feet for most subjects. Any further than around 15 foot minimum focus starts to become a problem, especially when trying to view/identify hummingbirds and warblers.

Low Light Optics

Astronomical binoculars are in a special category. These binoculars are optimized to gather as much light as possible by having large objective lenses for their magnification compared to general birdwatching or hunting binoculars. Common combinations are 7x50, 8x50, 10x63, 20x80, 25x100. Look for the specification of exit pupil size. For daylight viewing, the exit pupil can be 2.5mm to 4mm. For best night viewing, the exit pupil should be 5mm to 7mm. Anything over 7mm is no better, since the human pupil doesn't dilate any more, and therefore it wouldn't be useful. All the information above on lens coatings and prism glass types are also relevant to low light optics.

Other Features

Other features found on binoculars add to the value. Rubber coating the outer shell is nice to provide grip, comfort, and shock resistance. Another valuable feature is being waterproof and filled with inert gas like nitrogen or argon. This is not only useful for keeping water out of the binoculars, but it keeps them from fogging on the inside, and keeps dust from getting inside the optics. Some binoculars are promoted for birdwatching or hunting, but they are really very similar. The only difference with hunting versions are that they are camouflage in color. Speaking of color, it would be best to keep the shiny material off any binoculars for wildlife viewing. Anything shinny, may spook animals. You may paint over any shiny material, if needed.

Quality binocular manufacturers

Here is a list of manufacturers who make quality models of binoculars. Please note that some of these manufacturers also make inexpensive binoculars that aren't very good, such as Bushnell and Barska. Alpen, Barska, Brunton, Burris, Bushnell, Celestron, Eagle Optics, Fujinon, Kowa, Leica, Leoupold, Meade, Minox, Nikon, Pentax, Steiner, Swarovski, Swift, Vortex, Zeiss, and Zhumell. Some brand names I consider with having a high value for the price are Swift, Bushnell, Zhumell, and Nikon.

Discount Binocular Online Retailers

Here are a few bargain online retailers with a good selection of binoculars.

http://www.binoculars.com/

http://www.opticsplanet.com/

I hope this article helped you make your binocular decision. May you enjoy birdwatching, wildlife viewing, or hunting for many years with your new binoculars. If you find this article helpful, please let your friends know of it or otherwise link to it across the Internet.

binocular cut away view

A cut away view of a roof prism binocular.