Contrast vs Phase Detection autofocus – What it means and why it matters.
Mar 5, 2018
John Aldred
John Aldred is a photographer with over 25 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.
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Often, we hear much talk about the advantages and disadvantages of phase detection vs contrast-based autofocus systems. But not everybody knows what that means or why it matters. I had a rough idea, but I didn’t really understand it myself until I watched this video from photographer David Flores for B&H. In it, David explains how each of the two systems work, when it’s best to use one or the other, and how various camera AF systems work today using one or a combination of both methods.
Understanding the strengths and weaknesses of each can be the difference between getting or missing your shot. For a portrait session, you can just try again, most of the time. But for unrepeatable events, like weddings or sports, you need to understand how your camera sees the scene to ensure it’ll nail focus every time.
The 4-minute video does a good job of explaining the systems, although you may need to watch it 2 or 3 times to really understand the differences if have no idea at all about how they work. Especially when it comes to how mirrorless cameras utilise phase detection, as well as Canon’s dual pixel AF system.
Well worth a watch.
John Aldred
John Aldred is a photographer with over 25 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.
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