Lately I have been asked a lot about aperture. Pretty much, “What is it and what does it do?” After reading PostSecrets one day, where a person confessed to being a professional photographer and had no idea what an f-stop meant, I thought to myself, “Wow. I wonder how many “Professionals” really don’t know a thing about aperture?” I’m definitely NOT judging! We’ve all been there and have all had to be taught at some point. So if you already know about aperture then I’m sorry. This is going to be a boring post, but for those who still have a question or two I hope this brief explanation helps.
Aperture is the hole in the lens that lets the light in to reach the camera’s sensor or film. The aperture or hole can be set at different sizes measured as f stops. f 1.4, f 2.8 etc. You’ve all heard that before. The main thing to remember is that the smaller the number like f 1.4 the BIGGER your hole. The bigger your number f 22 the smaller the hole. Remember that and you’ll be peachy. The aperture combined with the shutter speed are your two main controls for your exposure but lets not worry about shutter speed right now.
My pictures were taken with a Canon 5D MarkII and a 50mm f1.4 lens. So my lenses largest aperture is f1.4. This picture was taken with a shutter speed of 1/25 and at f 1.4.
Now that we have pictures to compare, lets compare them. You’ll notice the top picture has blur or bokeh and the bottom picture is more crisp. The difference can be seen in how dirty my floor is. Embarrassing! The top giving you a shallower depth of field. Bigger f stop, smaller hole, more of an overall focused photo. Smaller the f stop, bigger the whole, bigger the blur. Getting it? The other difference is the bottom picture is darker. This is when your shutter speed comes in. Your shutter speed is measured in fractions of seconds. The bottom picture is 1/6th of a second, my shutter opened to let light in for 1/6th of a second. Don’t get aperture and shutter confused. They are two separate mechanisms to let in light but they work together. The top pictures shutter speed was faster at 1/25th of a second combined with a large aperture, made for a really nice photo. The bottom photo set with such a small aperture needed more light so I made the shutter speed longer. Why didn’t I set the shutter speed even longer for more light? That’s when you start getting bad blur and camera shake. The next thing you can change is your ISO. Your ISO determines how sensitive your image sensor is to the available light. Turn your ISO higher if you’re getting the shakes, lets in more light, and it may just be the difference between a blurry and crisp photo. Just be careful how high you set your ISO because the higher it is the grainer your picture will be.
So I know I said this was going to be about aperture and it kinda turned into a lesson about aperture, shutter speed, and ISO but I hope you realized they all work together for exposure. The easiest and best way to understand it is to turn your settings dial OFF of the green box and put it on manual. Then start with one non moving subject and play with your settings. What if you had a really fast shutter speed, with a medium aperture? Now go into a brighter room. What do you have to change to get the picture you want? How about in a darker room? Don’t be afraid to learn how to use your camera. Play around, have fun and learn!