Binoculars!

Besides good quality outdoor clothing, there is probably no product that transcends the borders of outdoor sports like good quality binoculars. You’ll find them put to good use by boaters, skiers, hikers, bikers, hunters, fishers, birdwatchers, rock climbers….well, you get the idea. When you are ready to purchase one of these fine instruments, the hard part is how to make an intelligent and appropriate purchase from the vast range of brands, styles, powers of magnification, and prices.

Simply put, there are times when a high-quality, light weight and expensive pair of binoculars are absolutely necessary, and then there are times when another selection, very reasonably priced, will be an appropriate choice. The key is getting some background information about which magnifications are used for what purposes, information about how different binoculars are manufactured, what that means to their performance, and how all that relates to how you plan to use them.

So, with that in mind, we’ve put together a basic primer on binoculars that should get you a long way to narrowing your selection…..read below on “How to Buy Binoculars” for some good basic information, and for more help in making your selection, stop in or give us a call.

 

How To Buy Binoculars

The pair of binoculars you buy will probably end up lasting you a lifetime.  The following discussion should help you determine which features are important to you in your particular use of these wonderful optical instruments.

Magnification/Lens Diameter

• Every pair of binoculars should have a pair of numbers stamped on them that reference power of magnification and the size of the front (“Objective”) lens.   An example would be 8 X 40.

• The first number (8 in this example) refers to the magnification, or how many times closer an object will appear than with the naked eye; in this case, it will appear 8 times closer than it really is.   There are many compromises in optics, and this is one of them:  the higher the magnification, the smaller the field-of-view (how large an area you can see at a given distance), and the more difficult it is to keep the image steady.  Higher magnification will not only magnify what you’re viewing, it will magnify hand movement as well.  Holding binoculars without the aid of a support will work fine up to and including 10-power models.

• The second number (40 in the above example) refers to the diameter of the front lens of the binoculars, the objective lens.

• The objective lens gathers the light that will eventually reach your eyes

• In general, a larger objective lens means more light will be transmitted to the eye, resulting in a perceived “brighter” and “crisper” image; however, it will also result in a larger, heavier pair of binoculars.

Brightness

• Binoculars come with a variety of brightness levels, which means the amount of light transmission through the multiple lenses of the binoculars to the eye

• The primary deciding factor in determining brightness is the size of the exit pupil, which is the size of the beam of light that exits your binoculars to be used by your eyes

• A larger exit pupil will allow more light to reach the eye, which is a benefit if you plan to use your binoculars in lower light conditions but not as necessary if they will be used outdoors in the sunshine

• To determine the size of the exit pupil, divide the objective lens diameter (millimeters) by the magnification power.  Our 8 X 40 would be 40 divided by 8 or an exit pupil of 5mm.

• A 3-mm to 5-mm exit pupil is generally adequate for normal viewing.   A 7-mm is best for low-light use.

Prisms — Porro Prism vs. Roof Prison

• Prisms are located inside the binoculars and they transmit light from the objective lens to the eyepiece and focus the image right-side-up for correct viewing by the human eye

• Binoculars come in two prism designs: porro prism and roof prism.  Which one’s for you?

  • A porro prism offsets the eyepieces from the objective lens to allow more brightness to be let in.  However, this makes the binoculars larger.   They are also generally less expensive than a roof-prism binocular of the same quality.

  • A roof prism aligns the lenses in a straight configuration, which makes the design smaller. This style should be chosen when size is a consideration, but the image is not as bright as with a porro prism of equal quality.

Field of view

• Field-of-View is the measure of how much area you can see through your binoculars at 1,000 yards

• Generally, the higher the magnification, the less the field of view

• This information is always printed either on the instruction sheet or directly on the binoculars

• The field of view for a 7x binocular is usually 7 degrees, or 369 feet at 1,000 yards

• A wider field of view, up to 9 degrees, is considered a wide-field model and is best for wildlife viewing

What does price have to do with selection?

This is a common question, and it has to do mostly with 2 variables:  1) the quality of the glass used in manufacturing the product and 2) the number of lens surfaces that are coated and the number of coats-per-lens-surface.  These two variables will determine the clarity of the image reaching the eye and the total light transmission at the exit pupil.  Most inexpensive lenses are clear in the center portion of the lens, but have abnormalities toward the edges.  The best (and most expensive) of lenses will be clear throughout the entire surface of the lens, and these are more costly to manufacture.  Also, there is always a portion of light transmission that is lost do to reflection of light at each lens surface.  To accommodate more light reaching the eye, the lens surfaces of more expensive models are covered with a non-reflective coating, resulting in additional manufacturing costs.  The more coatings, the more light transmission, the more cost.

Does it really make a difference?  That can be answered by how you will use your binoculars.  If you are keeping binoculars on a table next to the cabin picture window for occasional use, a moderately priced pair in 10x50 porro-prism binoculars would work fine, as you would not be concerned about weight, size, nor fine detail/contrast.   However, if you will be glassing hillsides for long periods of time in search of wildlife, you will want a higher quality lenses and coatings to provide maximum light transmission, and a level of clarity that will prevent eye strain and headaches.  The greater contrast attainable with premium binoculars will aid in separating background structure and the objects on which you are focusing.  You will also appreciate the compactness and lighter weight of the roof prism style of binocular.

The information on this sheet should get you close to determining the right model of binoculars to purchase, but for a complete discussion of optics choices, contact a Joe’s expert at 888-468-6563 or stop by to view our complete selection.  If we do not have the particular model you need, we can special order to your specifications.

BINOCULAR MODELS TO CONSIDER