iPhone 5S Camera Autofocus Speed Test

December 24, 2013

Mini globe, remote control and earphones for AF speed test

In this article I want to talk about the Apple iPhone 5S autofocus (AF) performance. As an enthusiast photographer, I am used to shooting with a fast-speed AF DSLR cameras.  In the past I was shooting with Canon L lenses, which provide me very fast AF performance to get the job done. With mobile phone cameras this is a bit different story, and mobile cameras are behind in offering the same AF performance that you get with DSLR or mirrorless cameras.

Having said that, most people probably don’t need or won’t take advantage of a higher AF performance, but some people fill find it useful. Fast AF performance can help in many situations, including: shooting fast moving subjects, for subject tracking, when rotating AF between several subjects in a short period of time, for sports photography, kids running in the back yard, etc.

When I bought the iPhone 5S, one of the first things I was interested to know is how good the AF speed is. This is something that is being ignored in many mobile phone review websites, and I know that information is important for some of you.

Yesterday and today I took my iPhone 5S camera for an AF speed test, shooting both indoors and outdoors to check how the AF performs in both daylight and indoors (dim light).

My overall impressions very good. When I test the AF at infinity-to-macro distance outdoors, I found that the iPhone 5S camera focus very fast and accurately. I didn’t measure it with a stopper, but it was around 0.5 sec. to  1 second more or less, depends on the lighting and contrast of the subject being focused.

The lens seems to always do a full movement before it locked on the subject. It doesn’t matter if the subject  was further away or behind the subject. That delay causes relatively a significant delay, and that’s something that I didn’t experience with my Nikon or Canon DSLR cameras.

Nevertheless, for the casual photographer, the AF performance is pretty snappy, but it wasn’t designed for capturing fast moving subjects, as it too slow for that job. By the time you spot the subject and focus on it, the subject will already moved from that focus point and you might get a blurry image / out of focus image.

In video the AF performance was a bit faster, and this is probably due to the more limited focal length, as the lens don’t need to move all the way down and this can speed up the focus speed. I am not hundred percent sure about this, but I felt that the AF speed slightly faster. If you have more information about this, please drop me a comment in the comment section below.

Here’s a test video that demonstrated the AF speed in various lighting conditions and against various distant subjects.

Focusing at a specific areas is dome by tapping at the area where the subject is. One problem that I had with the focusing system is that it locks the exposure when I touch focus and I wanted more control over the exposure. The good news is that since iOS 5 you have the option to lock the focus and exposure by tapping and holding your finger on the give subject for a few seconds.  You’ll notice that the focus rectangle will start flashing. Now remove your finger and AE/AF lock indicator will appear at the bottom, showing that from now on, the focus and exposure are locked. You can disable the AE/AF lock by tapping again to refocus on your subject.

AE AF lock iOS 7

AE/AF lock indicator on iOS 7

In order to get the fastest AF performance and prevent the autofocus to hang, you should shoot in a well lit environment and make sure that the subject is well lit. The iPhone 5S AF uses contrast-detect AF, which works best in high contrast scenes, and therefore the performance degrades in low-light.

There’s nothing too spectacular about the iPhone 5S back-camera AF performance but doe casual shooting, you’ll find the AF performance responsive and adequate for your needs.  When you shoot in burst mode, the

I was testing the AF performance in video mode and notice that there is not continuous autofocus on iOS7 / iPhone 5S.  The camera will continue to autofocus prior for pressing the record  button and lock the focus when you press the record button or lock the focus at a specific point using tap-to-focus or using the AE/AF lock which works for video as well. So in short, you have to continuously tap on the screen where the subject is to keep it in focus while shooting video.

In the next iPhone 5S sample video you can see that when the subject moves , persimmon in this case, the iPhone 5S back camera doesn’t refocus on the subject. When the subject moves from the focus plane, it becomes out-of-focus and therefore blurry.

I think that there is certainly room for improvements, but for general day-to-day use, I find the iPhone 5S to be pretty decent.

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