Coming into focus: how Panasonic’s DFD gamble may yet pay off

Panasonic’s DFD autofocus system tries to determine distance information without masking pixels as most on-sensor phase detection systems do.
We’ve been impressed by what we’ve seen so far of the autofocus changes Panasonic introduced with its new S5. The latest version doesn’t iron-out all the quirks but continuous AF for stills, in particular, appears much improved. But beyond this, the details we were given about how these improvements had been achieved are interesting. They help to highlight both the benefits and the continued challenges of the company’s Depth-from-Defocus system.
It’s a system with a poor reputation in some quarters but one that’s continued to improve significantly in recent years. The S5 shows both how far DFD has come as well as hinting at what’s still needed.
What is depth-from-defocus?
Fundamentally, focus is a a question of distance: adjusting the lens optics until the light rays from a subject at a particular distance converge on the sensor plane.

The alternative: phase detection
Most manufacturers have settled on phase-detection as the heart of their AF systems: this views the target from two different perspectives then works out how much the focus needs to be moved in order to bring those two perspectives …
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