Binoculars for Bird Watching

Good binoculars provide superior clarity and image quality with the least distortion and discoloration.

Things to consider when buying binoculars
1. Minimum magnification should be 7x35. Larger multiples of 8x, 9x, or 10x each give a larger image. You might find 10x binoculars can be rather unwieldy since they get heavier as they go up in power.

The first number given is the power of magnification, and the second number is the size of the front or objective lens. For example in 7x 35 the image will appear 7 times closer. The lens diameter will be 35 millimeters. A larger lens lets more light in and give you a clearer image. Get the highest power you can keeping in mind that there can be a large weight difference and you may get tired carrying heavy binoculars around.  Because birds are small, and often in shaded areas it is desirable to have a wider objective lens, allowing more light in for a brighter image.

2. Test to see if the barrels of the binoculars flex fairly easily. They should move easily but if you hold them out they should not move by them selves.

3. Make sure you can bring the barrels of the binoculars close enough together so that the image you see merges into a single, clear image within a single, perfect circle?

4. Some binoculars do not focus on objects up close, so you may miss a fleeting bird. Try to focus on something close. While doing this also check to see if there is any distortion in the image. Poor quality binoculars may

5. The exit pupil is another thing to consider. The exit pupil is the diameter of the image as it leaves the eyepiece lens. If the exit pupil is smaller than your eye's pupil diameter the image may appear dark and less clear. A binoculars exit pupil should be 4 mm or above for general daylight use, or 6-7 mm for low light viewing. To determine the exit pupil of a pair of binoculars, divide the size of the objective lens by the magnification. For 7x35 binoculars we would divide 35 by 7 and find that these binoculars have an exit pupil of 5 mm, a good size for general bird watching.

6.  Lens coating will provided better contrast and image quality, as well as extending the life of your binoculars.

Learning to use your new binoculars
In bird watching you are trying to spot small objects that move very fast. The best way to see a bird is to first focus on it just with your eyes. Then without loosing focus bring the binoculars up to your eyes. You can easily practice this before going on a bird watching trip.

Also, look for a pair with a rubber casing. These are more resilient to nicks and scratches and better able to withstand the jolts that can throw some binoculars out of alignment

Eye Relief
Eye relief is important if you wear glasses is. Eye relief is the maximum distance in millimeters that your eyes can be away from the eyepieces and still see the whole picture. Most glass wearers need extended eye. Binocular manufacturers try to provide this relief through the use of rubber eyecups that can be rolled down. Often this is not enough! Some binoculars are constructed with extended eye relief for glass wearers.

How Optics Work
Inside the binoculars or telescope is a series of glass lenses. The lens nearest the eye is known as the eyepiece. The lens farthest from the eye is known as the objective lens. Inside the housing between the eyepiece and the objective lens are combinations of other lenses and glass prisms. These are used to magnify or bend light. A longer light path gives more magnification.

In binoculars reflecting the light into a folded path using a pair of prisms increases the length of the light path.
In a telescope magnification power is increased by increasing the length of the lens.

Telescopes
If you are viewing waterfowl, shorebirds, and perched birds of prey a telescope is great. You have more power than binoculars will give you letting you see much farther.
A reasonably priced telescope with a zoom eyepiece and magnification ranging from 20x to 45x is a good place to start. Add a lightweight, sturdy tripod that easily extends to eye level.