Tuesday, August 23, 2011

General Binocular Questions

Eagle Optics,

I am new to bird watching, but experienced friends have recommended your binoculars. However, I do not know what some terms and abbreviations in your descriptions mean. Please explain: roof prisms and ED. And how do I decide between 8x42 and 8x32?

Thanks,
Eleanor



Eleanor,

Thanks for your interest in Eagle Optics.
Roof prism binoculars can be recognized by their straight barrels.
Roof prisms are a type of prism built in to binoculars with straight barrels.
They are, in general, more durable and easier to waterproof than the other kind of full-sized binoculars (Porro prism binoculars, which have a jog in the barrel).

ED stands for extra-low dispersion, and is a type of high quality glass built into some binoculars.

If you are comparing binoculars of equal quality in a 32mm and 42mm, the only determination will be how much weight you’re willing to carry and what kind of light gathering you need. The first number, 8, is your magnification, so everything will be magnified by 8 times.

The last number, 32 or 42 in this case, is the diameter of the front lens in millimeters. The bigger that second number, the more light will be let in (for brighter images in low light), but also the heavier the binocular will be (because it is bigger and has more glass).

I hope this helps answer some of your questions.
You can also visit this section of our website http://www.eagleoptics.com/articles/technical-guide/ for explanations of many more terms you might have questions about.

Thanks,
Eagle Optics

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