A Tale Of Three Pictures

A Tale Of Three Pictures

Controlling Exposure with a Smartphone Camera

It happens all the time, doesn’t it? Something catches your eye, you pull out your phone, start up the camera app and snap a picture. Then you look at it and “Aww, what happened?” How about an idea to take better smartphone pictures?

There are usually two things that can go wrong with getting that snapshot with your phone. Either it’s out of focus (which I’ll discuss in a later blog post) or the lighting is all wrong. But the secret here is that it isn’t actually the lighting that’s wrong, it’s how your camera is handling the light.

Here are three pictures. All taken within seconds of each other.

f/2.0 1/20 sec ISO 400
Correct Exposure
f/2.0 1/30 sec ISO 64
F/2.0 1/60 sec ISO 64

As I said, these were taken seconds apart. No time for the light of the setting sun to change appreciably. So, what changed? The camera’s exposure settings. Old-school photographers were notorious for fiddling with the shutter speed and aperture (ie, opening size) settings of their camera. But there are no settings like that on a phone, right? The answer is tricky, because you do have a little bit of control over this.

Most camera apps on smartphones allow you to set a point on the screen that the camera is focused upon. By default, the camera is focusing on whatever is in the middle of the image. But you can change this focus point by tapping the screen. So, for example, if you are taking a picture of your child riding a bike and their face is near the top of the image, tap on their face to make sure the face is in focus.

Now for the fun part.

Not only does the camera app focus on the spot where you clicked, but it also reads the light level of that point, and adjusts the camera sensor’s sensitivity to light and the shutter speed to compensate for it. So, if you click on a dark spot in the image, the photo can appear overly lit, or over-exposed, as seen in the first photo above. Click on a lighter spot, and the photo will be darker, as seen in the third image. Alternatively, if you click on something that falls between the two extremes, and you get a well-exposed photo. You can play with this to adjust the lighting to suit your tastes. For example, I actually prefer the look of the third image, even though it is normally considered under-exposed.

Special Note

This tip works best for scenery type photos. When you have a specific subject in your photo, the focus point should be on the subject to ensure they are kept in focus. tapping elsewhere will shift the focus to a different point and, depending on the distance from the camera to the spot on which you are focusing, your subject may appear blurry.

So, go try it yourself. It might help you take better smartphone pictures. Or it might let you experiment and get a little artsy with your photography. Whatever works for you. Have fun with it.

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