Set focus and exposure for iPhone photos


Set focus and exposure for iPhone photos
Mac Tip #527, 14 March 2012

When you point your iPhone at something to take a photo it may focus on the wrong thing, or make a subject against a light background too dark. Learn how single-tap focus and exposure locks can give you better pictures. This Tip uses the built-in Camera app on an iPhone 4S, running iOS 5.1.

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Quick Start

  1. Tap once on an image to place focus and exposure in that spot.
  2. Tap and hold on an image to lock focus and exposure for that shot.

Want more detail? Read the full Tip below.

Focus and exposure problems

It’s a common frustration that a camera doesn’t necessarily focus on the same part of an image as you do. When you take the shot you find the bird you were looking at is blurry while the branches behind it are nicely sharp.

With the iPhone 4S you can lock the focus.

You may also find that the bird in the tree is dark, while the sky behind it is very bright. Again, you can lock the exposure, so the bird is brighter.

It’s the same kind of issue as when you take photos of people against a window. The camera adjusts exposure for the bright window and your friend’s face is too dark.

Where’s the dog?

As an example, take the photo below. There’s a fairly bright deck outside the window and a mainly light-coloured dog on a black rug.

Almost impossible to see is the mainly black dog on the same rug. The camera exposure was set automatically for the light coloured dog and the bright window.

How many dogs are in this photo? The answer is two. Sasha is black on a black rug and almost impossible to see.

How many dogs are in this photo? The answer is two. Sasha is black on a black rug and almost impossible to see. The white paws are a giveaway.

Tap once to focus and set exposure

With iOS 5 you can make the iPhone camera focus on a particular part of the image with a single tap on the screen. That tap also causes the iPhone to adjust its exposure.

Line up your shot and then tap once on any part of the screen to make the camera focus on that spot. For example, if you’re taking a photo of your dog you may like to ensure the camera focuses on the eyes.

Here’s how it works.

Hold the iPhone steady while you line up your shot. After a moment, a large blue rectangle appears around the area where the iPhone will focus. If that’s not the best focus or exposure point, tap on the screen in the part you want to focus on. A smaller blue rectangle marks the focus and exposure area.

You may also notice the image brighten or darken if the tap changed the area the exposure was set for.

Exposure set for the black dog.

Exposure set for the black dog.

In the photo above I tapped on the part of the screen where the black dog’s head is. Now the focus is set there, but the exposure has also dramatically changed. Now the deck outside is too bright and the detail in the light coloured dog has blown out. But you can see the black dog quite nicely.

If I’d spent longer on preparing the shot I may have been able to find a sweet spot where both dogs were lit fairly well.

Tip: If you’re going to want to take loads of photos of your dogs don’t get one that’s essentially white and the other black. You’ll never win and beautifully exposed photos of the two of them together will always be almost impossible.

Tap and hold to lock focus and exposure

You may like to set the focus and exposure for one part of the image but then reframe the shot. To do that you need to lock the focus and exposure.

AE/AF Lock.

AE/AF Lock.

To lock the settings, tap and hold on the image. After a moment the blue rectangle pulses a couple of times and the words AE/AF Lock appear at bottom centre of the image. The focus and exposure are now locked to the point you tapped on.

To release the lock tap on another part of the screen.

Use another photo app

At the moment the built-in Camera app changes both focus and exposure with the one tap on the screen. You may prefer to be able to set them separately. If you download a different camera app from the App Store you may be able to do that, and more besides.

For example, ProCamera gives you a yellow target circle you can place to adjust exposure and a blue rectangle you can place for focus, along with many other features.

The iPhone 4S camera takes great pictures anyway

The outward-facing camera on the back of an iPhone 4S has a stunning 8 megapixel resolution. I find it takes great pictures for me.

For example, one day recently after our dogs had been groomed I belted them in to the back seat of the car and quickly grabbed the shot below. To add the picture to the web site I had to resize it and reduce the quality, but it still looks pretty good. This photo hasn’t had any other editing applied.

Oshi and Sasha  in the car. February 2012.

Oshi and Sasha in the car. February 2012.

With a bit of cropping and exposure adjustment after the fact, of course, it could look even better.

But remember, if you have the opportunity before you snap the photo, tap the screen to place focus and control the exposure before tapping the shutter button.

Tell us in the Comments online how this Tip helped you.

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2 Comments

  1. Eljey said:

    The information you’ve supplied has saved the day for me! I recently got an iphone 4 (it was a gift – if I’d known that the 4s has such a better camera I would have encourged my friend to get that one for me!) Nevertheless, I think the camera on the 4 is pretty good for my current needs. I was having some difficulty with focussing etc. but I think your article has supplied the answers. I followed your instructions and saw a difference immediately. Many thanks.

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