Canon Patent Application: Major Defocus AF Improvements

[Richard CR]

In this patent application (2024-073200) Canon is looking at improving the racking of the lens from near to far to find focus quicker.

Canon Patent Application: Major Defocus AF Improvements – Canon Rumors

 

[neuroanatomist]

Can't be implemented soon enough.....

 

[mxwphoto]

Please also implement more AI in object recognition when focusing. Would be great to be able to recognize birds among branches and focus on that instead of nearest twig.

 

[Maximilian]

Can't be implemented soon enough.....

So true.
And please, not only for the top cams for the first few years, but for all.

 

[koenkooi]

Please also implement more AI in object recognition when focusing. Would be great to be able to recognize birds among branches and focus on that instead of nearest twig.

That would be a big change compared to how it currently works, detection and focus are not coupled and the focus is open-loop. This is how I think it works, based on first hard observation and people complaining on the interwebs:

1. The camera looks at the scene, detects a bird, draws a box around it
2. An eye! Camera draws a tiny box around the eye, which sadly also includes a twig behind the bird.
3. The camera tells the focus system to focus on the area inside that tiny box
4. The focus system says "ah, DPAF estimates that's 2.12 meters" and tells the lens to focus to 2.12m
5. The lens focuses to 2.12 meters, or the closest step its motors and encoders can do
6. The lens tells the body "I'm at the distance you told me"
7. The body starts the exposure

The issue that you mention, bird vs twig, is due to the detection and focus system being separated between step 3 and step 4. DPAF picks the twig in step 4. And the RF70-200 f/2.8L has shown that step 5 depends on the calibration of the lens and that might need a firmware update when it consistently misfocuses by the same amount.

One way of alleviating this, is to have the body do an extra detection between step 6 and 7, which uses contrast (aka pre-DPAF on-sensor focus) to judge critical focus. My M6II has a menu option for "Release priority" vs "Focus priority", which would be a good way to toggle this behaviour. This would also help @neuroanatomist to focus on perfectly straight features in the 'wrong' orientation.

It would be even better if users could do an AFMA style calibration themselves to avoid needing a firmware update to make the lens focus properly, like the RF70-200L needed.

 

[john1970]

Agree with others that solving this issue is critical to improving mirrorless AF performance.