Objective Lens – What’s the ‘Big’ Deal?

October 15, 2009 by binocular

When you’re looking at buying a pair of binoculars, one of the factors that inevitably comes into play is the size of the objective lenses. But what’s the difference? Does it really matter how large the lens is? It certainly does, and it can affect more than just the quality of the image. Let’s find out if bigger is better.

Binoculars have two objective lenses – they’re the big ones (usually) that you point away from yourself. They gather light and direct it into the binoculars towards your eyes. That’s the key factor to consider as far as size goes: how much light can the lens pull in. A larger lens has more surface area, so more light will strike it and consequently be pulled in. A larger objective lens will lead to more overall light entering the unit, which will result in a brighter picture for your eyes.

A large lens does not necessarily correlate to a larger image, however. How large objects appear when you look through a lens is a factor of the magnification or power of the binoculars, not by how large the objective lens is.

Before you run out and the biggest monster you can find, realize that much of the weight is directly attributable to the objective lenses. If they are huge, you’re going to pay for it by having to lug around a massively heavy viewing device. You may want to balance out a practical size for your use with the light gathering potential.