Types Of Binoculars

Learning how to find the best bird watching binoculars !

Binoculars for bird watching come in two basic types, Porro-prism binoculars and Roof-prism binoculars. How do they differ and what are the features? Let's take a look at the two types:

Porro-prism

Below is an image of the porro-prism style of binoculars.

These are the normal angled-body binocular design that has been most commonly seen in the marketplace over the years. You can distinguish them by the tell-tale M shape they appear to form when they are standing on their barrels on your table or hanging down from the strap around your neck.

This type of binocular uses an external, central "focuswheel" that you turn to adjust the focus the image of the bird you are looking at. This focusing method allows for very sharp images of fairly close birds and also offers very precise focus when birds are as close as six feet away from you.

Advantages

-offer fast focusing

-tends to brighter images due to greater transmission of light in this style

-close focusing on birds just 6 feet away

-gives a wider field of view - this is the amount of area you can see in your field of vision when looking through the binoculars

-offers greater depth perception

-lower cost - when comparing binoculars of the two styles with the same cost - porro prisms are usually the better buy

Disadvantages

-	lack the durability and compact styling of roof prism models
-	weight due to the large prisms which offer better -transmission of light but add to the heft and harder to hold for long periods
	-bulky - again because of larger prisms used - difficult for people with small hands
	-external focusing mechanisms can be jarred out of alignment when in rough terrain

Roof-prism

The image below is a roof-prism style of binocular.

This style has a pronounced H-shaped appearance as opposes to the M or zig-zag shape of the other.

Advantages

-more compact and easier to hold than comparable porro-prism binocular

-more rugged due to closer optical and mechanical tolerances in manufacturing process

-because of the design they can be made weather-resistant and waterproof

-greater durability due to fewer external moving parts

-offers a better ratio of power-to-weight so that a 20x roof-prism style usually weighs less than a 20x porro-prism model

Disadvantages

-more expensive

-don't focus as closely as porro-prism style

-don't usually offer as bright an image as porro-prism