I've had a lot of people ask me to help them learn how to use their cameras in manual mode. So I'm doing a short series of videos and blog posts about aperture, shutter speed, and ISO for beginners. Aperture is first because it's my favorite.
Watch the video tutorial below:
What is Aperture?
Aperture is one of 3 basic camera settings that you need to adjust in order to get the correct exposure (ISO, aperture, and shutter speed). Aperture is the size of the hole in the shutter that lets the light into the camera. It's like the pupil in your eye. Your pupil changes size depending on whether you are in a bright area (smaller pupil) or a dark area (larger pupil).
How is it Measured?
Aperture is measured in f-stop numbers. The smaller the number, the larger the aperture hole. The larger the number, the smaller the hole. This seems backwards, but once you practice enough, it will be easy to remember.
1. Aperture Controls Light Coming In
Aperture helps you get the right exposure by controlling how much light is coming in to the camera. A large aperture allows more light in. A small aperture allows less light in.
So, if your camera is telling you that it's underexposed and needs more light, you can select a larger aperture (smaller f-stop number). This would give you a larger hole to let in more light so that you aren't underexposed. If your camera is telling you that it's overexposed and needs less light, you can select a smaller aperture (larger f-stop number). This would give you a smaller hole to let in less light so that you aren't overexposed.
2. Aperture Controls Depth of Field
Depth of field is the zone that is in focus around your focal point. You could have a depth of field where everything 4'-6' away from your camera is in focus. You could have a depth of field where everything 8'-200' is in focus. There are other factors (lens focal length and focal point distance) that help control depth of field, but aperture has the biggest influence. Which is why it's my favorite.
If you want to have a lot in focus, you need a large depth of field. A smaller aperture (large number), gives you a larger depth of field.
If you want to isolate your subject and have only a small plane of focus, the you need a small depth of field. A larger aperture (smaller number), gives you a smaller depth of field.
Depth of Field Example
Depth of field is easiest to understand once you see it. The first gnome photo below was shot at f2. This is a large aperture. It gives a small depth of field. That's why the gnome in front that I've focused on is the only one in focus. All the gnomes behind him, plus even the bird in front of him are out of focus.
But what if this is a gnome band, and all the other gnome bandmates are mad they are out of focus? For the second gnome photo, I switched my aperture to f11. It's a smaller aperture and a larger depth of field. So even though my focus point is on the first gnome, the entire area of focus is much larger. The bird and all the gnomes are now in focus.
Now Go Experiment!
You can read a million tutorials about aperture, but the best way to learn to use it is to practice. Go play with your camera and try shots at different apertures. See what happens to your exposure and to your depth of field. Get artsy! Make mistakes! Have fun and learn!