Okay let's get on with the discussion of aperture - we're talking f-stops and Depth of Field. Have a look at your camera's mode dial; on one side you'll see a bunch of icons and on the other, some letters.
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| Image courtesy of Nikon.com |
What we're looking for is the aperture priority mode, which is 'A' on Nikon and 'Av' on Canon. When you set the camera to this function, you are giving yourself control over how large or small the aperture is, basically: how wide the shutter opens when you take a photo. Whoopie doo, you say? Well, remember the little girl from our post on storytelling? (Click HERE) I had the f-stop set too low, giving a very shallow depth of field which makes it hard to tell what she's looking at.
Whoah Nellie! Too many terms that need definitions. Aperture priority mode allows you to select what's called the 'f-stop' by using either a button or another dial, depending on your camera (check your user manual). And here's the tricky bit - the lower the f-stop, the wider the aperture. Huh. Don't ask me why - I'm a creative type, remember?
Okay, now for the next definition: Depth of Field. This determines how much of your photo, from foreground to background, will be in focus. If your depth of field is shallow (or narrow), a good part of the image will be out of focus, highlighting the main subject, as in this photo:
See how the background is blurred? That's what depth of field can do. Notice how her eyes are in focus but the raindrop on her hair is out of focus - that's a very narrow depth of field. In the photo below, the mushrooms are in focus but everything in front of and behind them is out of focus.
So now that we know what f-stop and depth of field are, we need to know how they work together. The lower the f-stop, the wider the aperture, right? What's easier to remember is: the lower the f-stop, the shallower the depth of field. They both get smaller or larger together. An f-stop of f5.6 will give a very narrow depth of field, while a higher f-stop of, say, f22 will give you a photo that's in focus pretty much from front to back.
But why do we want to bother with all this? Look again at the statue above. If I had taken that with a higher f-stop, the background would be more in focus, introducing too much clutter into the photo. The statue (which is the subject) would compete with the non-essential parts of the image. Show the viewer only what you want them to see.
These next two photos are taken with a higher f-stop. The colours of the car are reflected in the trees, but instead of blurring out the trees completely I opened up the aperture a little, allowing the viewer to see where the car is.
This beach photo is taken with the highest f-stop of these four images, to get as much as of the vista as possible in focus.
There is, however, a problem with opening up the aperture. A wider opening means... you've got it - more light gets in. And it's not much good to us having a bunch of photos that have fantastic focus but are all washed out. Rats. But not to worry, there's a way to fix the problem. It's a balancing act between the f-stop (aperture) and shutter speed (how long the shutter is open). We'll talk about shutter speed in another post. In the meantime, see what happens when you play with aperture - have some fun!
