Besides composition, choosing the correct exposure is essential for your photography. Achieving that requires understanding how metering works and how to control the camera’s settings. Here, some cameras excel and others let you down.
Metering measures the amount of light entering your camera through the lens (TTL metering). In turn, it tells your camera what settings it needs to get a good exposure. You then decide whether to keep these settings or change them.
Years ago, cameras used the average brightness of the scene to set the exposure for photos. This, wisely, is known as average metering. Then the smart technicians in Japan decided that the camera should be a bit smarter and adjusted that average to consider the different amount of light and dark in the image, the average was modified . This is much more accurate in many cases.
However, the marketing departments of the camera companies decided that they should name that modified average to attract customers. So the average metering mode was given a bunch of stupid labels: Sony chose Multisampling. Olympus chose ESP, which stands for Electro-Selective Pattern metering; I’ve always wondered if this is intentionally ambiguous with Additional Sensory Perception. Canon chose Evaluative, Nikon chose Matrix, Panasonic chose Multiple, and Leica chose Multi-Field. Whatever you call it, for most photographers it’s easiest to think of it as an average metering.
Medium metering can be very suitable for landscapes with little contrast in the image. The resulting image will be as bright as your eyes see the scene. In many cases, this mode works well in giving you a good photo. However, there are times when it doesn’t.
This is one of the first things a photographer should learn: capturing a bright scene with medium metering can lead to underexposure. Even some experienced photographers get this wrong. I recently interfered in an online chat. A business owner looking for advice. A professional photographer said he should reduce exposure when shooting products with light tones on a white background. They were wrong; the level of exposure needed to increase.
It’s counter-intuitive, but capturing a bright scene will inadvertently cause your camera to underexpose. Your camera wants the world to be in the Goldilocks region, neither too bright nor too dark. If you want to dive into the techniques, it assumes that the world is medium gray, or 18% gray. If you’re shooting a scene brighter than that, your camera will try to compensate and darken the image.
Conversely, if you’re taking a photo that’s mostly black, the camera’s light meter will assume that black is also medium gray, and thus increase the exposure.
Go out into the snow or a sandy beach on a sunny day, and you’ll see what I mean. Also, here is a test to prove this. Take a blank sheet of paper and draw a small X in the center so that your camera has the focus point. Fill the frame with paper and shoot. The paper will not be bright white, but rather dull gray in the image.
Now, do the same with something black. Fill the frame with it and shoot. That will also be the dull gray in your photo, not the black one.
There are times when you may want the camera to take advantage of overexposure or underexposure. Lowering the exposure makes the colors look more saturated. So, point your camera towards sunrise or sunset, colors will be emphasized, but foreground subjects will become silhouetted.
Increasing the exposure adds more white to the colors, making them less saturated. But it also brings out details in the dark without creating noise. Fortunately, modern camera sensors are improving their ability to retain detail in both highlights and shadows. I rarely have to think about noise now. I can now retrieve overexposed highlights in the sky, which cameras made a few years ago could not recover.
There are metering options other than average. As its name suggests, the center balance feature measures the light in the center of the frame, ignoring the edges. That’s great for head and shoulder photography when you want the exposure on the face to be accurate.
Spot metering measures a small point, usually in the center of the frame. That could be as small as 1% of the whole picture. You can position this on a single subject that you want to expose properly and it will ignore the rest of the lighting of the scene. If your camera’s spot metering is centered in the frame, you’ll need to place the subject there. You can lock exposure by pressing and holding the shutter button halfway, or using the Auto Exposure Lock (AEL) button, after which you can recompose. Some cameras have point-to-point metering that deprecates this method.
There is more than one method for doing most things in photography, and despite these great metering modes, I rarely use them. Instead, I set the camera to medium metering and checked the image and histogram that I displayed in the viewfinder. Then I changed the exposure using the front and rear dials.
If you want the best advice I can give on buying a camera, buy one with two command dials. They are located on top of the front and rear cameras. You rotate one with your index finger and the other with your thumb to change the camera’s exposure settings. Some cameras are missing, only a dial. As such, they require you to fumble, find and hold the +/- button and then rotate the dial simultaneously to change exposure settings.
Having two dials is much easier to operate than that. There is a worse design, however. These cameras have a second wheel, but it is located in the middle right side of the back of the camera. Besides rotating, it can also be pressed in four directions like buttons. Everyone I know who owns one of these accidentally presses the dial when trying to rotate it with their thumbs. The bad thing is those with a dial that changes function when you press it. Photographers who own these also struggle to turn the wheel without accidentally pressing it.
In manual mode, you will usually have one command dial set to change the shutter speed and the other to change the aperture; I like the aperture on the back dial, while others like the front dial. When you decrease the aperture size with your thumb, you can balance the amount of light entering the camera with the front dial, which will decrease the shutter speed.
However, I only use manual mode about ten percent of the time. Most of, my camera is set to aperture priority. Why? It does a lot of the heavy lifting for me.
In aperture priority mode, which is usually marked as A on the mode wheel, but oddly enough, Av on Canons, I can set the aperture to whatever I like using the rear wheel. . Then I was able to quickly adjust exposure using the front dial. The front dial is still changing the shutter speed but from the starting point chosen by the camera. My desired exposure is rarely more than stops above the camera’s recommended exposure value. Therefore, I can select the value I want in a flash. It will take longer in manual mode and I might miss the action.
Also, in aperture priority mode, it was correctable even if I made a mistake and shot before setting the correct exposure. There’s always enough dynamic range in the shot for me to fix it in post-processing, starting with the camera’s default exposure settings.
Aperture priority is useful when shooting in different light levels, such as at a wedding when a person steps inside out. Furthermore, exposure is limited by the maximum and minimum size of the iris of the lens. Regardless of whether it’s extended or minimal, if you shoot in a hurry and make mistakes, the result is a usable photo, even if it’s not perfect.
In shutter priority and manual modes, the longest shutter speed on my camera is 60 seconds and the fastest is 1/32,000 second. It is relatively easy to have an overexposed or underexposed image at the limits of those parameters. Furthermore, stepping from a dimly lit room to a bright tropical day can mean changing the shutter speed from 1/30 second to 1/32,000, which takes 30 presses of the dial.
There is always more than one way to take a photo, and maybe you have a different approach to metering and exposure than I do. I haven’t even mentioned ISO or flash here, which deserve their own articles.
Perhaps you prefer to have a single command dial. It would be great to hear your thoughts in the comments.
