Canon Patent Application: AF calibration for DSLRs

In this patent application, we see that Canon is developing AF calibration for it's DSLR's.  Since this functionality exists on Nikon's latest DSLR's it's no great surprise that Canon wants to do this as well.

Essentially, Canon using focus stacking, will take multiple pictures, and then the user chooses which one is best in focus.

Sounds easy enough to me.

In this patent, Canon is concerned, that if the user is shooting a flat subject perpendicular to the camera's sensor, there is the chance of miscalibration.

 an image capture apparatus according to the present invention is a replaceable imaging apparatus an imaging lens, an imaging unit for imaging the subject image formed by the imaging lens, the imaging lens A focus detection unit for detecting the focal position of the camera, and a shooting control unit that performs focus bracket shooting that causes the imaging unit to capture a plurality of images while controlling the focal position of the shooting lens to change by a predetermined amount. A display means for displaying an image photographed by the focus bracket photographing, and a subject suitable for performing focus detection of the photographing lens by the focus detecting means before performing the focus bracket photographing. A guide showing a region and a second region in which a suitable subject is placed to determine a focused image for the user Display control means for displaying on the display means.

From this, it sounds like the display will automatically choose guide areas where there is a suitable subject in the frame.

Japan Patent Application 2019-139017