But let’s back up: last week I got a little carried away with talking about the way that you can play around with shutter speed to capture motion in you pictures, and I forgot to really talk about shutter speed and light. Do you remember how I said that most exposures are only a fraction of a second long? Well the important thing to keep in mind is that the smaller the fraction the more light that you’re going to need to get a proper exposure.
This can get a little confusing because your camera will leave out the 1/ bit and just list the bottom number. So instead of seeing 1/60, you’ll just see 60. If your shutter speed is set to 125 then you’re letting light into your camera for less than half as long as you would be if your shutter speed was set to 60, and so you’re going to need a lot more light to get a correct exposure.
Sometimes it helps to visualize:
1/250 < 1/125 < 1/60 (now mentally remove the 1/)
Aperture works in a similarly obnoxious way, but first let’s talk about what aperture is.
Aperture is the hole in your camera lens that that allows light to come through. This hole will get bigger or smaller depending on your aperture setting. The bigger the hole the more light you let in, the smaller the hole the less light you let in. Aperture settings are measured in f stops. Typical aperture settings are as follows:
Like shutter speed, aperture settings are confusing in that the smaller the number the larger the hole. It will probably help you if you check out this chart. As you can see f/2 is a really large hole that allows lots of light in, whereas f/22 is a teeny tiny hole that allows hardly any light in.
But, but, but! Aperture doesn’t just control light it also controls depth of field. What is depth of field you ask? Well, you know how in some pictures only one tiny part of it is sharp and the rest of the image gets all soft and fuzzy?
Then in other images the entire scene is fairly sharp and in focus? Depth of field is a term that describes the range of sharpness that is present in an image.
I have a little demo here to demonstrate how various f stops affect depth of field. Notice how in the first images of f/1.4 & f/2.0 only one small bit of the orchid is sharp and distinct while the rest of the picture is super soft and out of focus. Pay close attention to how the background changes as you move up the f stops. Again with f/1.4 it’s just giant blobs of color, but by the time you get to f/22 the blob of white has transformed into a car (also by f/22 you can tell that my window could maybe do with a wash).
Whew, so that was a lot of information. Feel free to ask me questions in the comments if you’ve got any. Next week I’m going to talk about exposures, how aperture an shutter speed interact with each other, and easy ways to get a correct exposure when you shoot manually. For now here are your weekly links!
Margaret Durow’s work is stunning. So gorgeous.
Klara– I’m not sure of her last name but her work is amazing. She does street photography on film in Berlin. A girl after my own heart.