Using Lenses

The other day some stranger noticed my camera, (I had my 200 mm with a F/ 2.8 so of course my camera was hard to miss) and as we were chatting about it, i started telling him about my lens. He said "Can take photos really far away?" and I said "Well no I have smaller lenses than this that have more zoom." The man was completely confused. Sometimes, amertures have trouble figuring out the use of different lenses, when really it's very simple.

When you look at a lens, you'll notice a bunch of confusing numbers on it. Believe it or not, but these numbers really mean something! If you look at the end of your lens closest to your camera, you'll see some strange numbers, normally followed with millimeters. That is your focal length, a lot of people refer to that as the zoom. This one happens to be 18-135mm. That means, that as you move the ring closest to it, your camera can zoom anywhere from the smallest number to the largest. Those numbers above it, the ones on the line? That is the number you are using. In the picture below, it is set on 18mm (indicated by the little white line). The larger the number is, the farther you can zoom.

 So automatically you think that a lens that is 75-300mm is going to be bigger than a 70-200mm lens right? Well that isn't always a case. Remember when we talked about aperture? That is the ring that allows so much light into your camera.

Well that ring is located inside your lens (as shown to the left), and the larger your aperture is, the larger your lens is. Most lenses nowadays have a changing aperture, which means you can change it from F/30 to an F/5.6 (remember: the smaller the aperture value, the bigger the aperture hole) without changing your lens. Most cameras have an aperture of F/5.6 and it can get smaller (which means your aperture hole is BIGGER), but sometimes you need even more light than that, so they use a lens with an aperture of F/2.8

This lens is only 200mm... but its got an aperture of F/2.8

 (thats a HUGE aperture!)

And this little guy, is a 300mm lens, though its got a longer zoom, it is really really short and skinny.

Lenses also help control your Depth of Field. If you read my depth of field blog, then you remember there are three things that control your depth... Aperture, distance from subject, and FOCAL LENGTH. Now that you are more aware about what focal length is and how to find it on your lens, you will be able to control your depth of field better. Knowing your lenses apertures and focal length help you decided what type of lenses you want to buy for your favorite type of photography.