In this patent application (2024-053967) Canon is looking to improve the ability of the cameras to calibrate the eye control focus with the photographer. The eye control focus is featured on older EOS film cameras and more notably, the Canon EOS R3. Eye Control AF differs from Eye AF, as Eye Control AF moves the focus point to where you are looking through the viewfinder, and Eye AF locks onto the target's eye as the focus point.

The camera does eye control by shining infrared light into your eye and measuring the relative location of your pupil. Using that, the camera can calculate where you are looking. Because of this, and because it's a very individual measurement, each person has to be calibrated to use eye control autofocus. Canon in this patent is looking at increasing the precision without necessarily increasing the time it takes to calibrate eye control.

According to Canon's machine-translated patent-speak;

An object of the present invention is to provide a line of sight detection device that can perform highly accurate correction while reducing the burden on the user.

According to the patent application, it appears as if the detection is sensitive to the diameter of the user's pupil. This surprised me, but it does stand to reason because Canon does specify that you need to take calibration indoors and outdoors – which would cause users to have a different pupil size with the variation in light intensity. It should probably be noted that it may even be a good thing to expand on the calibration to include overcast conditions, etc.

According to Canon Europe;

You have to confirm that you're looking at it, then it will move, and you need to follow it with your eye. This needs to be done with the camera in horizontal and vertical orientation, both inside and outside, but you don't have to do it all at once. You can come back to a calibration.

So anything that Canon can to do make the calibration of the camera's eye control auto focus easier and more accurate is welcomed. It will be interesting to see how Canon advances this technology over time.

As with all patent applications, this is a look into Canon's research and may not end up in an actual patent or product.

Source: Japan Patent Application 2024-053967

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5 comments

  1. The R3's Eye Control does not work for me. I still love the camera, but wish this feature worked. Don't purchase the camera IF that feature is your main reason for doing so. I wear glasses and that has got to affect the performance of the IR beam. I also had RK surgery (radial keratotomy) on my eyes years ago, so even if I remove my glasses it's unable to calibrate. I suspect the scars on my cornea from the operation are causing the light to scatter or reflect enough that it can't lock on. ??? It could be a very helpful feature if they can get it to work better and over a wider range of users.
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  2. An old style rubber cup that completely seals around the eye would help with consistent pupil size, the only light would be from the EVF.
    I think it's not a great solution for everyone because for example with wildlife we won't see an animal for a while and thin it could appear for less than a minute... I don't think anyone will keep their eye in the eyecup because they'll want both eyes to search for the next subject. I could be wrong - it's just my thinking.
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