Can someone tell me what it means when your looking at binoculars and the say 10×25 or 8×32 and also which?

2 Responses to Can someone tell me what it means when your looking at binoculars and the say 10×25 or 8×32 and also which?

1. jerryb says:

   April 8, 2011 at 1:16 pm

   Magnification: The ratio of the focal length of the eyepiece divided into the focal length of the objective gives the linear magnifying power of binoculars (sometimes expressed as “diameters”). A magnification of factor 7, for example, produces an image as if one were 7 times closer to the object. The amount of magnification depends upon the application the binoculars are designed for. Hand-held binoculars have lower magnifications so they will be less susceptible to shaking. A larger magnification leads to a smaller field of view.
   Objective diameter: The diameter of the objective lens determines how much light can be gathered to form an image.This number directly affects performance. When magnification and quality is equal, the larger the second binocular number, the brighter the image as well as the sharper the image. An 8×40, then, will produce a brighter and sharper image than an 8×25, even though both enlarge the image an identical eight times. The larger front lenses in the 8×40 also produce wider beams of light (exit pupil) that leave the eyepieces. This makes it more comfortable to view with an 8×40 than an 8×25. It is usually expressed in millimeters. It is customary to categorize binoculars by the magnification × the objective diameter; e.g. 7×50.
   Field of view: The field of view of a pair of binoculars is determined by its optical design. It is usually notated in a linear value, such as how many feet (meters) in width will be seen at 1,000 yards (or 1,000 m), or in an angular value of how many degrees can be viewed.
2. muncie birder says:

   April 8, 2011 at 2:02 pm

   The first number is the magnification. The 2nd number is the size of the objective Lens (the larger of the two. The one in front) The larger the objective lens the brighter the image so the 2nd would have a brighter image than the first but you would not really know the difference unless you were to be using them in low light conditions. 10 magnification binoculars have more image shake than 8 mag binoculars so that might be a problem for you. I have both 8 and 10. I like the 8 better. The 8 also tend to have a wider field of view which helps you to find the object you are looking for in the binoculars. That is most important when you are looking for a bird in a clutter of limbs in a tree or a bird flying through the sky. I did have a pair of 10×25 binoculars for about 10 years until I dropped them on the ground and knocked them out of alignment. I do like my 8×40 much much better though. I would get the 8×32 if they have good reviews.