Shopping for Binoculars
Once you've narrowed down your choice of binocular style, magnification power, objective lens size, and field of view, try the following tests on the array of suitable binoculars in your local optics store. Save your final decision regarding price until you've examined what's available.
- Compare binoculars of the same magnification power by holding one above the other. Alternately look through each binocular, comparing them for brightness and clarity. Then compare the best binoculars from your first selection with a third group, each time choosing the binoculars with the best characteristics. Continue this process of elimination until you have thoroughly examined everything that's available
- Check optical quality by holding the binoculars at arm's length, and checking the exit pupils to see if they are blocked at the edges by gray shadows. Carefully examine the print on a billboard or sign to see if you can read the lettering at the edge of the field as well as at the center.
- Check that the binoculars have "fully coated" optics; all optical surfaces should be coated with an even purple-violet or amber hue. Carefully examine the objective and eyepiece lenses for scratches.
- Be sure that all the mechanical parts move smoothly and that the bridge supporting the barrels does not wobble.
- Outside the store, check alignment by looking at a rooftop or horizontal power line.
- Look at the edge of a backlit sign or building to see if it is fringed with a band of bright color. This fringing indicates an inferior optical system that cannot focus light of different wavelengths to the same point.
- If you wear eyeglasses, be sure the binoculars feature long eye relief.
- After narrowing the field to a few choices, select the best binoculars you can afford.
To read the Cornell Lab of Ornithology's latest binocular review article "The Age of Binoculars" from Living Bird magazine, Winter 2005, click here.