More Info About Binocular Lenses

This is a continuation of last week’s article about binocular features needed by hunters.


Magnification: Makes Objects Appear Closer than They Are!

But what does this mean? One x is what you can see with the naked eye.  Thus, a 7x binocular promises to magnify an image 7 times larger than with the naked eye. Another way of looking at this is: A magnification of 7 means that the image you are seeing through your binoculars seems 7 times  closer that it really is. Generally, the higher the magnification of a pair of binoculars, the narrower the field of vision. Thus, the closer the image appears, the less you see around that image. If you are focusing on a deer with a pair of 8x binoc’s, you will see much more of the scene around that deer than you would with 10x binoculars.

Binocular Lens Diameters

The diameter of your lens determines the binocular’s ability to gather light. When the lens is larger, it lets in more light so you can see things in greater detail. If you want more light during the hours when deer are most active (dawn and dusk), then 7 x 50 is a great choice. This is because , at lower power, your view will be brighter and you will have a wider range of vision than with stronger binoculars. Objective Diameter: This is the lens at the opposite end of the glasses from the eyepiece; its size is expressed in millimeters. Essentially, it tells you how much light this pair of binoculars can deliver. Understanding the Numbers: With a pair of binoc’s rated at 7 x 42, this is expressing – “7” is the magnification and “42” is the objective diameter (amount of light that can be gathered to see an image).

An Example of a Roof Prism

Prisms: In a nutshell, roof prisms are lighter but porro prisms provide a clearer, sharper image. The roof prism can be more compact. With the porro lenses, however, you get more depth perception.

An Example of a Double Porro Prism


Full Disclosure: Although I sell binoculars and other optics, I will not mention them in this article.  My mission is to share information about using the proper equipment while hunting!


The 2 images showing the two types of prisms in binoculars are from Wikipedia. I am using them through the “Fair Use” Clause. This article is educational.


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Published in: on December 14, 2009 at 8:51 am  Comments Off on More Info About Binocular Lenses  
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