Magnification of binoculars

[rogerr]

Can anyone explain this to me in simple terms please.
I want to buy a lightweight pair of binoculars to watch the birds in my garden, which is not very big.
I managed last year with my dad's old ones which are 7x50 but they are so heavy.
I have just had a look on ebay and found 8-24x25 and 10x25 and other numbers and am now totally confused.
Any help appreciated.

[Fitzer]

The first number in the specification for binoculars is the magnification, so your dad's make things appear 7 times larger (or nearer). The second number is the diameter of the front lens (known as the objective lens) in millimeters, the larger this is the more light can be gathered and the brighter the image that you see. The second set of figures you have quoted indicate that the binoculars have a 'zoom' capability, varying the magnification between 8 and 24 times. If you are birdwatching in a garden do not be tempted to go for large magnification as these are very difficult to hold still enough to get a good view without the image wobbling all over the shop. A good compact pair of binoculars for general use might be a set of 8x25. You ideally need to try binoculars out before you buy them to see if they suit and what the quality of the image is like, good binoculars are not cheap I'm afraid so you might want to consider buying secondhand from someone who is upgrading.

[kempie]

The first number is the magnification of the eyepiece

7x ... 10x ... 20x

Where 2 numbers exist, this is an indication that the binoculars are variable zoom

8-24x ... in this case from 8x to 24x

The final figure indicates the size of the object lens in mm

The larger the object lens the more light is captured and thus a better(!) image (depending on the quality of the lens, of course).

[rogerr]

Thanks both of you--I now fully understand.
I will take your advice Fitzer and try some out.
Good point about not going for too high magnification as I had great trouble with wobbly images last year.
Cheers
R