Does the above image look familiar to you? Chances are, if you’ve ever picked up a camera, you’ve experienced focus hunting – the phenomenon whereby the camera and lens are unable to identify the plan of focus inhabited by your subject, and endlessly drives forwards and backwards through a set range of focus “hunting” for it.
Well, Canon has just designed a new focus technology that sets out to solve this issue – something that would make millions of photographers, especially me, jump for joy.
The patent (2024-073200) (originally spotted by Canon Rumors) describes the solution as follows: “The focus control device includes a focus detection means for performing focus detection by a phase difference detection system, and a control means for controlling the drive of a focus lens included in an optical system based on a focus detection result obtained by the focus detection.
“In a search operation of acquiring a focus detection result while driving the focus lens in a search direction, the controller sets a drivable range of the focus lens based on the search direction and a position of the focus lens, and when a focus detection result for a position within the drivable range is obtained, the focus lens is driven based on the focus detection result, and when a focus detection result for a position outside the drivable range is obtained, the focus lens is driven in the search direction without using the focus detection result.”
This diagram from the patent illustrates the plane of focus hunting phenomenon, promising to solve the issue by enabling the camera to better identify the range within which the plane sits (Image credit: Canon • JPO)
As with most patents, deciphering the technical jargon is pretty tricky. In short, the system comprehensively determines the search direction and autofocus direction, and calculates the difference between the search start position and the current position.
The system then continuously determines the search and defocus direction based on the current and previous frame, until it ultimately establishes the correct focus drive amount and search direction to find the correct plane of focus.
There’s obviously much more to it than that – including plenty of diagrams and flow charts – but I think that’s the gist of it.
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The caveat, as always, is that this technology may never find its way into a final product. After all, Canon has been a prolific patenter for almost 40 years and secured nearly 3,000 patents in 2023 – so there’s no guarantee that this will go anywhere.
But if it does… boy, will my hat be off to the designers behind it.
Here, share some of the schematics pain from the patent (Image credit: Canon • JPO)
