Here’s a handy one for you point-and-shoot photographers. Have you ever wanted to get one part of the scene just right, but you could never get the colors to pop out? Sometimes you know more about the thing you want to photograph than your camera does. You know you want the sky to be blue, really blue, but your camera assumes you want everything to have equal importance. How can you put an end to this? Auto exposure lock, that’s how.
Photo By Tim Green
Learning how to "expose for" something
You’ve probably heard of this before. Photographers often talk about “exposing for the sky” or “exposing for the grass,” but what does it all mean? What are they really talking about?
An exposure is a complicated way of talking about a photograph. Whenever you “expose” your camera’s sensor to light, you are creating an exposure. It happens every time you press the shutter and take a picture. Light enters, hits the sensor, and an image is formed. The way light enters, how much gets in, and how it spreads across the sensor is mostly the determined by two things; the aperture and the shutter.
By controlling the aperture and the shutter, you can control exposure. That is to say, you can expose for one thing or another.
Different things require different kinds of exposure. To get a blue sky, you often need a different combination of aperture and shutter speed values than to get a lush green pasture. Whenever we talk about “exposing for” something, we mean choosing the ideal aperture and shutter speed to bring out as much color as possible from that thing.
A fun experiment you can try
I love photography experiments. That’s how I learned most of the art. So here’s one you can try, using your camera’s ordinary automatic mode.
- On a clear day, take your camera and point it at the sky. Zoom in as much as you can and try to include the sky and nothing else. Take a picture.
- Now, just moments after taking the first picture, point your camera more towards the ground and zoom out. Include some of the sky in the shot, but not a lot of it.
- Compare the skies of the two photos.
Here’s what’s likely to happen. The sky on the first photograph will appear very blue, and the sky on the second photograph will probably look a lot whiter. Why? Because your camera makes certain assumptions based on what it sees. It then attempts to “expose for” whatever is in its field of view. If it’s the sky, you get a nice blue sky. If it’s the green grass, you get bright green grass but the sky appears white.
Auto exposure lock gives you control over what to expose for
There are times when you will want to expose for something, change the way you frame the shot, and then take the picture. This often results in a more visually appealing composition. You could get a very blue sky by pointing your camera directly at the sky, but what’s the point if you can’t work that pretty sky it into an interesting landscape photo? That’s what auto exposure lock allows you to do.
Here’s what you need to do to use auto exposure lock:
- Point the camera at the thing you want to expose for. That could mean pointing the camera up the sky, or zooming in to fill the frame with some bright green grass. It could even mean zooming in on your friend’s face to get the colors just right.
- Press the auto exposure lock button. On most cameras, it’s on the back facing panel, and it’s labeled “AE-L” for auto exposure lock.
- Reframe your picture to include everything you want to include. If you zoomed in to capture your exposure settings, zoom back out and frame the photo. It helps to pay attention to the rule of thirds and other composition guidelines.
- Take the picture. The thing you want to highlight will appear much more colorful and detailed than every other element in the scene.
Auto exposure lock is a great primer for manual photography.
You’ll find yourself doing this all the time once you learn manual photography. Except, it won’t have a fancy name. Instead of allowing the camera to pick an aperture and shutter speed to expose for something, you’ll use a light meter, experiment, and do it yourself. Once you’ve picked which aperture, shutter speed, and ISO speed values you want to use, you’ll recompose the shot and take it. Just like above.
Now is a good time to get started with auto exposure lock. It’s a skill you’ll never forget, and it almost always comes in handy. I’m happy to help you out if you encounter any roadblocks along the way.
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