Binocular magnification

[beedeez]

Hi all,

I would be most grateful to receive advice on what the numbers on binoculars mean e.g. 20x50 or 10x90 etc. they all seem to have them and I'm about to purchase some. I have received conflicting advice so I'd much appreciate an opinion from anybody out there who uses this website.

What I need are very powerful ones for landscape, sea scape and bird watching (eagles in particular).

Hope somebody can help - best wishes,

Brian Davis

[Clanad]

Binoculars are often specified by a set of numbers such as 7�35 or 8�40, the first number indicates the strength of magnification (how many times closer the subject is to you, 5 times closer, 7 times closer, 10 times closer) and the second number is the size of the objective lens measured in millimeters going across the lens. The size of the objective lens will determine how much light it can obtain for effective viewing. The higher the number, the larger the lens; in effect allowing more light to pass through thereby projecting a brighter image and viewing experience. (Source: Just Binoculars)

[john91]

Also don't forget the more powerful, the bigger and heavier they will be, anything much above 10x50 will be impossible to hold steady and will require a tripod or mount.

[Loosehead]

Echo the above. Trouble is as john points out if you want powerful ones for bird wathcing then you will not be able to hold them steady enough to see so it's a trade off between power and usability.

[Fitzer]

This is why dedicated birdwatchers carry binoculars (for spotting) and a telescope on a tripod (for thorough examination)

[sloperton]

You might find this website helpful. It confirms what the other answers have said:

http://www.alpenoutdoor.com/about/terminology.shtml