subject: 12 Tips For Selecting Quality Birding Binoculars [print this page] Bird watching can be one of the most rewarding outdoor experiences, but it can also be the most frustrating. The first challenge is to simply find the bird. Then, you must be able to follow its rapid movements through the trees or across a field.
Binoculars that work well for boaters, hikers or hunters won't necessarily be the best for birding. Look for a pair with a bright image to help distinguish subtle features, particularly in dim light. Also, being able to focus them quickly is a must.
Here are a few tips that will help you select the right pair of binoculars for a successful bird watching adventure.
1. Image quality and field of view
Binoculars are described as "7x35" or "10x50." The first number refers to the magnification "power," and the second is the diameter of the objective lens (the big one in front) in mm. The bigger the objective lens, the more light the binocular can gather. Those that have a larger ratio between the magnification (first number) and the objective lens size will provide a brighter image than ones with a smaller ratio. (For instance, 8 x 42 provides a brighter image than an 8 x 32.)
The field of view is how wide a view you get. It is a published specification for all high quality binoculars. FOV is usually expressed as view width in feet at 1000 yards or in degrees. Look for at least 250 feet at 1000 yards. Lower power binoculars will have a wider FOV than higher power binoculars. Since birds are fast moving, a wide field of view will help you locate them faster.
2. Porro Prism or Roof Prism?
Think of binoculars as two small telescopes strapped together. In fact early binoculars were just that. But there were problems. First they were very long, and secondly, the view was upside down and backwards. Not the best for birding. An Italian gentleman by the name of Porro solved this problem by installing two prisms in each tube of the binocular. The light comes in through the objective lens, hits the first prism and is reflected into the second, which reflects the light to the eyepiece. Thus the light makes two 90 degree turns on its way to your eye. Porro prism binoculars can be recognized by the "shoulders" on each tube.
Roof prism binoculars work the same way, but the "roof" - shaped prisms are oriented in the tube such that light follows essentially a straight path through the tube to your eye. So there are no "Shoulders" and Roof prism binoculars have straight or slightly conical shaped tubes.
There is essentially no difference in optical performance between roof and Porro prism binoculars. However, for the same size (8 x 42) for example, Porro prism binoculars are less bulky, but may be slightly more expensive.
3. Weather Proofing, Coated, Gas Filled
Look for binoculars that are water proof and fog proof. Good binoculars will be filled with inert gas - preferably argon - but nitrogen is good, too. Since these gasses have no moisture content, the inside of the glass will not fog in changing temperatures. However, the outside surface of the lenses will fog if they are taken from a cold environment to a warm, humid environment. The solution is to let the binoculars adjust slowly to the warmer climate. Do not try to wipe the condensation off, as this may damage the lens and the condensation will rapidly reappear.
Optical glass is coated to prevent internal reflections from reducing the clarity and brilliance of the image. In good binoculars, all glass-to-air surfaces will have multiple coatings. This is called "Fully Multi-Coated." Beware of binoculars that claim "coated optics" or "multi-coated optics."
4. Magnification
Most binoculars will have 7, 8 or 10 power magnification. A higher number isn't always better. Most birders feel that 7 or 8 power is a good choice. Opinions against the 10 power binoculars are that the higher the magnification, the smaller the field of view and any shaking of the hands will be magnified.
5. Exit Pupil Size
The exit pupil is the size of the image that exits the eye piece of the binocular. To see it, simply look at the eye pieces while holding the binocular about a foot from your face. The exit pupil size is computed by dividing the power into the objective lens size in mm. So an 8x32 binocular would have an exit pupil of 4mm.
The exit pupil is important because it determines the brightness of the image. At dawn and dusk, the human eye will dilate to about 5mm, so for satisfactory viewing in dim light, a binocular of 8x42 (exit pupil of 5.25mm) or 10x50 is necessary.
6. Weight
Typical standard-sized birding binoculars will range from 20 to 40 ounces. Reasonably light weight is good, but don't let the weight be the determining factor. A heavier model is often helpful for steadier viewing. Binoculars weigh just a fraction of what your arms weigh. It's the weight of your arms rather than the weight of the binoculars that tires you out. A wide neck strap or harness will make carrying them easier.
7. Focusing
The two basic types of focus systems are center and individual. For birding binoculars, center focusing is the most common and convenient and typically the most preferred, as both eyepieces can be focused at the same time. A separate diopter adjustment on one eyepiece (usually the right one) helps to compensate for differences in the strength of each eye. An acceptable minimum focus distance is 18 to 20 feet, but many birders prefer models with a closer focus of 8 to 13 feet.
8. Diopter Adjustment
On mid and high quality binoculars, the right eye piece will have a focus ring which is independent of the main focusing knob. The reason is that most people's eyes are not the same strength. The diopter adjustment allows you to achieve perfect focus with both eyes.
9. Eye Relief
The distance behind the binocular eyepiece at which the entire field of view is clearly visible is known as eye relief. This is a very important specification for those who wear eyeglasses or sunglasses. This distance can vary from as little as 5mm to as much as 23mm. Most current models feature fold-down rubber eye cups so eyeglass wearers can bring the binoculars in closer to the eyes to significantly improve viewing. Some models have what's known as long eye relief for those without the need for glasses, but they do not have a particularly wide field of view. Decide which feature is most important before making a purchase.
10. Inter-Pupillary Distance (IPD)
This is the distance between the pupils of your eyes. Binoculars are hinged in the middle so they can be adjusted for varying IPD. This adjustment should be stiff enough so that normal carrying and use won't shift it.
11. Zoom Binoculars
In general, zoom binoculars have a host of problems that can't be easily overcome. Fixed-power binoculars, of similar price, will always out-perform the zoom variety. At low power the view is almost half that of the fixed-power. At high power the image quality is not as good and is likely poorly merged. Similar fixed-power binoculars offer as much magnification as you can steadily hold and the image quality will be far superior.
12. How To Use Binoculars
Setting up and using binoculars is dirt simple. First, set the inter ocular dimension. Look through the binocular and open or compress the hinge until you see a nice, round, clear circle of your image which does not "black out" when you use the binoculars in normal viewing position.
Second, set the diopter adjustment. Set the diopter adjustment to zero. Then, look through the binocular as you normally would and cover the right lens with your hand. Focus on a target 25 to 100 yards away until it is sharp in your left eye. Then, cover the left lens and turn the diopter adjustment until the image is sharp in your right eye. Done! From here on, you should only have to adjust focus with the center focus wheel.
Good quality binoculars will probably be heavier than less expensive models, so use a harness rather than a neck strap. If you're birding or hiking, binoculars around the neck will get uncomfortable after carrying them for hours. The harness spreads the weight to your shoulders and back. Also, the harness keeps the binoculars from flopping around if you bend over or worse - you happen to fall.
Involve the Kids! Kids who show an interest in birding at an early age should be encouraged to join in the fun. Gift them with terrific kid-size binoculars that are designed with smaller features for little hands. This is a wonderful way for children to not only enjoy nature but to make it a special bonding time with parents and siblings.
Once you have chosen and purchased your binoculars, get comfortable with them. Practice before that first big birding adventure. Follow birds leaving your feeder to develop a feel for the speed of flight and the quickly changing focus. It's awe inspiring. Tune in and enjoy!
