Introduction
Hi. this is the second post about the basics of the built in iPhone 4S camera. The first post is here if you missed it. In this second post, I would like to write about adjusting focus and exposure.Focus and Exposure
In most situations, the iPhone will automatically set the optimal focus and exposure. However, there are a few situations when you may need to adjust the focus and exposure. In that case, just tap on the area you want to set the focus and exposure on.In the example below on the left, I wanted to take a shot of the bug but the autofocus focused on the wall in the background. Tapping on the area of the bug got it into focus (right).
 |  |
For those new to photography, exposure is how much light gets in the camera and determines how bright or dark the photo turns out.
The following is an example of setting the exposure. The photo on the left is auto-exposure. The guitar is very dark because of the light background. Tapping on the dark area (the light blue square on the photo on right) will set the exposure based on that area and will cause the overall image to be lighter. This may cause whiteout on the background (the view outside now cannot be seen), but sometimes this effectively creates a desired artistic feeling. I love to use this overexposed lace curtain background to take photos of my baby.
 |
In some situations, it is difficult to set the exposure if your subject is small or thin, for example the neck on this guitar. In that case, one solution is to lock the exposure and focus on another area and move the composition. This is called AE/AF lock and is achieved by continuing to press on a certain area for a few seconds. Both the exposure and focus will be fixed on that area and the text "AE/AF Lock" will appear above the shutter (left photo below). You can now move up and take a overexposed shot like the photo on the right.
 |
One problem doing this is that both the focus and exposure is locked making it difficult to maintain focus if you move your composition like in this example. This is a limitation for the built-in camera app. However there are several alternate camera apps such as Camera+ and 645 Pro which allow you to lock the focus and exposure separately. I'd like to write about these apps in the future.
Thanks for reading my second post. I'd appreciate any feedback and requests for future posts.
