Binoculars

Backyard BirdwatchingBinoculars are one of the key pieces of gear for any Backyard Birdwatcher.  They can bring the birds up close to where you can enjoy them more.  Not only can you identify new birds, but you can watch and learn the behavior of all your birds.

You might be wondering, OK, so what’s the best type of binocular to get?  The right answer is:  It depends.  There is NO “best” style of binocular.  Each one has its advantages and disadvantages.  So, what you first must determine is what you’re going to use your bincoulars for, where are you going to use them,  what aspects of bird and wildlife viewing are important to you, and what your budget is.

First, you need to know the basic terminology with binoculars.  Here is a diagram from the Eagle Optics website:

Eagle Optics Diagram

 

Binoculars models are described by their magnification and objective lens diameter (in millimeters).  So, for example, an 8X40 binoculars magnifies an image 8 times and has an objective lens diameter of 40 mm.  This tells you a lot about the binocular by itself.  The magnification is self evident.  But the objective lens diameter tells you a lot about how much light this binocular can take in.  The larger the objective lens, the more light it can physically gather in.  Also, this diameter will tell you a lot about how large the binocular is.  Other things being equal, the larger the objective lens, the bigger the entire binocular will be.  This will of course affect the weight.

Here are some other key factors you want to look at when comparing binoculars:

Field of View

This is a measure of how wide of an area a binocular can see when someone is looking through it.Binocular field of view  This number is measured in either degrees or the width of viewable field at an arbitrary distance from the binocular (standardized in the binocular industry at 1,000 yards).  This is shown on the diagram.  What this means to you is that a wider field of view number will be better when viewing moving objects (like flying birds) or in looking at a large area further away (like a marsh).

Close Focus Distance

Every binocular has a a minimum distance from it that an object will appear in clear focus.  This is called the close focus distance.  It’s dependent mostly on the internal design of the binocular itself.  But, a short close focus distance can come in handy when viewing butterflies or birds that are unusually close by.  An excellent close focus distance is the 5 to 8 foot range.

Eye Relief

Eye relief is the maximum distance in millimeters from the ocular lens of the binocular where you can see the full field of view.  So, beyond this distance, you will see less and less of the maximum field of view of the binocular.  This number is very important mainly if you wear eye glasses when using binoculars.  The reason is that glasses act to increase the distance of your eye away from the ideal viewing location of that binocular.   Every binocular has a specific eye relief number based on its design.  A very good eye relief is 14 mm. or more.

Roof Prism Vs. Porro Prism

Binocular model typesA roof prism binocular (shown on right) tends to be a more compact design for the same size objective lens compared to a Porro Prism model.  Some people prefer having a binocular that’s narrower and easier to hold.  As a result, most people tend to favor the roof prism models.  But, either one is fine from an optical point of view.    One related point is that roof prism binoculars tend to have more rugged hinges between the two barrels, which make them less prone to getting out of alignment.

Compact vs. Full Size

Binoculars are considered full size models if the objective lenses are greater than around 30 mm.  Less than this size are considered compacts.  The main advantage of compact binoculars is their small size.  They are easier to travel with and store in a small space.  Also, for people with very small hands or not very strong shoulders and neck, the small size and weight are easier to hold.  But that’s where the advantages end.  Full sized binoculars have larger ocular lens, which makes it much easier for almost everyone to look through and see a wide field of view.  Compacts usually have narrow field of views which make it much harder to find birds when pointing them in the direction you want.  Almost everyone I’ve gone birding with who’s used compact binoculars has complained about how hard it is to see the birds and identify them.  So, if you’re mainly going to use binoculars around the house or yard, I strongly recommend getting a full sized pair.

Magnification

Most binoculars for bird or nature viewing (or mostly everything else) are sold in the 7 to 10 power range.  I’ve found the optimal magnification for backyard birdwatching is around 8 power.  Some birders tend to like the 9 and 10 power models.  But, keep in mind the higher the magnification, the lower the field of view.  Also, if your hands tend to shake at all, higher magnifications will multiply the shaking movement and be harder to use.

 Lens Coatings and Quality

This is a VERY important factor to compare.Binocular lens coatings  Lens coatings are chemical layers on the inside surfaces of the binocular lenses and prisms that act to absorb reflected light that would otherwise bounce around inside the binocular making images fuzzier and dimmer.  In general, the better the quality lens coatings, glass quality, other materials, and construction used in the binoculars, the sharper and brighter the image you see will be.  Also, you will often have better depth of field to.  All this can make identifying birds far, far easier.  Of course with higher quality comes higher price.  So, the level of quality you can afford will come down to your budget.  My only advice is to buy the best quality binoculars your budget will allow.  High quality optics make your enjoyment of the hobby far greater and pay for themselves many times over.

Final Advice

It’s very important to try out binoculars before buying them.  If you can go to a birding festival or event, there are often optics dealers there with high quality binoculars and spotting scopes (usually not needed in the backyard, but can come in handy on occasion).     How a binocular performs and feels will differ greatly from person to person.  Factors such as distance between the eyes, face shape, hand size, and strength can make a big difference when trying different models.

For the backyard, I recommend  8 power magnification binocular and an objective lens in the 40 to 50 mm. range.

Get a good strap for your binoculars.  Most come with a basic strap. But, there are much better padded and harness straps that will make carrying your binoculars around much easier.

Again, buy the best binoculars your budget will allow.  I started out with a basic pair and gradually moved up, buying better binoculars each time.  But, I finally invested in a pair of Swarovski binoculars and absolutely love them.  The clarity and sharpness has made a huge difference in what I can see and enjoy – both in my backyard and at birding locales.

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Cornell Lab of Ornithology