How is the power(magnification) of a Binocular marked?Want to buy one; but can't understand how they differs!

Answer 1

They will be something like 8X35 or 10X40 or even 6 to 12X38.

In the first example, you have 8 power maginfication - something 80 yards away looks like it it 10 yards away - with a 35 degree field of view. (A full circle is 360 degrees)

In the second, you have 10 power magnification with a 40 degree field of view.

In the last example, they are adjustable from 6 power to 12 power.

Other things to consider is some will automatically focus, which is a nice feature unless you're using them in a wooded area or indoors looking out. They tend to focus on the nearest object directly in front of them. Some also have range finders and light gathering capability which is useful in low-light situations.

In a nutshell, purchase the best quality set you can afford. Depending on your uses, a maximized field of view may be more important than greater magnification.

Answer 2

Pater47's answer is good, except for one slight error. Yes, the first number is the magnification. However, the second number in the notation (the one after the "x") is not the field of view angle. Instead, it is the size of the objective lenses, measured in millimeters (the big lenses on the front). Bigger objective lenses gather more light, so they provide slightly better viewing in the early evening/morning, or when skies are overcast. The field of view is denoted by how wide an area you can see through the binoculars when you're looking at something 1000 yrds away (usually in the range of 280 -350 ft, higher is better).

Answer 3

To my knowledge, the first number (Example: 10 in 10x50) is the magnification factor (how many times the view is enlarged) and the second number is the diameter in millimeters of the outer lens.
Magnification is interesting at first sight but keep in mind that, all other factors (quality of the lenses -outer and inners, along with their coatings, other inner elements such as prisms, which impressively affect the quality of the result) being equal, the second number obviously gives an idea of the brightness of the image.
Well, "all other factors" never being equal, if you are looking for image quality, stick to a well-known brand and choose the bigger "second number" instead of bigger magnification, as your budget permit.