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Posted by: Phillip B on 2010-03-06, 12:14:45
Normally I would expect a spec like 6 x 30 to mean six times magnification and a 30mm front lens. A small boat sailor would normally choose a maximum of 8x because it's hard to hold steady anything stronger. But you can get image stabilised models now, so higher magnification is possible, albeit at a price and with a need for batteries (normally). The size of the front lens is a measure of light gathering power for a given magnification. Divide one by the other, eg, 30/ 6 = 5mm exit diameter. The human eye doesn't dilate more than 7mm, so that's the maximum that binocular designers would work to, eg, the popular 50mm front lens with 7x magnification. However, you mention "zoom ". Binoculars with zoom would be cited, eg, 6-12x30, meaning variable magnification from six to twelve times. At the 12x setting, the image will appear quite dark except in good light. Read on at [1] and come back with more if you need it, perhaps mentioning the brand that you're considering. |
