I hope Sony (and Mark) do not mind if I report their interesting article about the World’s Fastest Auto Focus Technology used by the A6000 :)
Here is the full text originally posted at Blog Sony.
Below is an overview of Sony’s latest technological advancement, The World’s Fastest Auto-Focus, written by Mark Weir, a Sr. Technology Manager here at Sony Electronics. This overview can be very technical for some, so you’ll understand why Mr. Weir is known as the professor around here. Please read on and hopefully, you’ll be as amazed by this technology as we are.
World’s Fastest Auto Focus Technology
By Mark Weir, Sr. Technology Manager, Sony Electronics
Digital camera technology is changing all the time, but some recent developments indicate that we are entering a period of exciting innovation. These developments are apparent in the revolution taking place in Auto Focus technology – and leading the charge is the AF system introduced in the new a6000. Until very recently, cameras performed autofocus in one of two ways – Phase detection with a dedicated optical sensor, and Contrast detection measured by the image sensor. “Hybrid AF” – autofocus systems that employ both approaches are reaching performance not possible just a short time ago.
Phase detection autofocus was introduced almost 30 years ago, and still operates on the same basic principles. A beam splitter directs light from opposite sides of the lens to a dedicated sensor which analyzes differences in Phase (luminance patterns), and determines the direction and distance the lens must be moved for the patterns to be aligned, and thus in focus. Phase detection AF has expanded to most all modern DSLR cameras, and has been steadily refined with the development of multiple AF points, predictive tracking and even specialized sensors for wide aperture lenses. Phase detection AF is quick, but its reliance on optics and mechanisms makes it bulky and expensive, and has trouble covering the entire scene.
Another approach to Phase detection has recently been developed which utilizes the camera’s image sensor – eliminating the optics and mechanics of the traditional design.
Contrast autofocus is far simpler – the contrast in the scene is measured and the lens moved until contrast is maximized – the point at which the scene is in focus. The advantage is simplicity and focus precision, although Contrast AF is typically not as quick as Phase detection AF.
The strength of the a6000 is use of both Phase detection and Contrast autofocus – while maximizing the performance of both with Sony’s Bionz X processor. Phase detection AF is provided by the newly developed 24MP imager, which includes 179 embedded AF sensors covering more than 90% of the frame, with focus speed as short as 0.06 sec. Covering more of the frame than most any other camera, a6000 can track even fast moving subjects and focus continuously at up to 11 frames per second. Contrast information is read from 25 areas of the image sensor and combines with Spatial Object detection based on recognition algorithms. Both Phase and Contrast detection AF systems can be used alone or together, based on direction from the Bionz X processor – even when shooting video. With the support of these two systems, photographers can enjoy ultra-fast, accurate and intelligent AF across nearly the entire frame – a potent combination not possible with earlier technology.
Much of a6000’s autofocusing performance is possible because of advancements in device technology – imagers with embedded AF sensors, processors with faster throughput, object recognition algorithms, and lens drive design. As device technology continues to advance, camera performance will advance with it, providing image makers with options for even greater creativity.
Sony A6000 store link list:
Sony A6000 at Amazon, Adorama, BHphoto, SonyStore. In Europe at Sony DE, UK, FR, IT, ES, AT, NL, BE, CH, FI, SE, PT, WexUK.
Silver A6000 at Amazon US, BHphoto, WexUK.
Sony A6000 with lens at Amazon, Adorama, BHphoto, SonyStore, Sony Canada, WexUK.
Silver A6000 with lens at Amazon US, BHphoto, WexUK.
Sony 70-200mm FE at Amazon, BHphoto, SonyStore. In Europe at Sony DE, UK, FR, IT, ES, AT, NL, BE, CH, FI, SE, PT
A6000 Gariz case on eBay in Black (Click here), Brown (Click here), Camel (Click here) and Red (Click here).