Here’s some information you might need to have in order to buy those new binoculars you have been wanting.
You’ve got your bird in your binoculars, but just what color is he?
Brightness is given in that second number in the details, 8×40. This number is called the objective. The larger the objective, the more light will be allowed in and the more detail you can see on the birds.
So do you need the biggest number you can get? No. Think about the times you will normally be looking at birds. If you look at them in bright sunlight fairly close, then binoculars with an objective lens of 35 will be fine.