This article presents the inventive solutions Canon has found to shoot beams of light into the camera's viewfinder in order to light up individual autofocus points. Six different approaches are shown using six Canon DSLR models between 1994 and 2009.
It's absolutely wild to me that this function would be so important as to justify all the time and effort to create not just two, but six entirely different ways of solving it.
The first one seemed perfectly adequate to me. But I guess that's why I'm not a Canon engineer.
For most stuff it's not a huge deal. Keep in mind however that for years the latest and greatest pro camera bodies were going to people getting photos at the Olympics and things like Formula 1.
Getting something or someone flying through the air at high and unpredictable speed perfectly in focus is pretty impressive
No. Modern cameras usually use a combination of contrast detection (pure image analysis checking the contrast of the region you want in focus), phase detection (an optical system where you split the income image in two and then compare them) and sometimes help of some sort of assist lamp.
Maybe in some niches, but for most modern ILCs (e.x. Sony E mount, Nikon Z mount, etc etc etc) it is typically some form or another of On-sensor Phase Detection coupled with Contrast Detection for finer tuning.
The biggest advantage compared to older SLR designs are that Phase Detection can now work with full light (vs whatever got split off on an SLR pentaprism for the dedicated AF sensor) and can work in conjunction with the contrast Detection for fine tuning focus.
Then, of course, all the predictive stuff added in the last 10ish years as far as processing sensor output to detect eyes/birds/motion/etc.
The only AF systems that use LIDAR are the one on the newest Hasselblad medium format mirrorless cameras (since DJI owns Hasselblad and can leverage the tech from drones/cinema cameras) and possibly some phones.
I suspect it's fairly challenging to implement since the LIDAR sensor doesn't operate through the lens, so you'd have to continuously align the depth map with the image to account for parallax; plus it's only useful for close-ish distances (since the lasers can't be too powerful) and can cause unwanted focus behavior with windows or reflections.
My uncle Richard is one of the inventors on Honeywell’s early phase‑detect autofocus. Patent US4333007A, which figures out both the direction and amount the lens needs to move instead of hunting.
Modern systems like Canon’s Dual Pixel AF in bodies such as the EOS R5 are very direct descendants of that idea, just implemented on‑sensor with far more processing power.
Every time I see an article such as this, I beam with pride. (Pun intended).
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[ 3.2 ms ] story [ 35.1 ms ] threadThe first one seemed perfectly adequate to me. But I guess that's why I'm not a Canon engineer.
Getting something or someone flying through the air at high and unpredictable speed perfectly in focus is pretty impressive
https://en.wikipedia.org/wiki/Autofocus
The biggest advantage compared to older SLR designs are that Phase Detection can now work with full light (vs whatever got split off on an SLR pentaprism for the dedicated AF sensor) and can work in conjunction with the contrast Detection for fine tuning focus.
Then, of course, all the predictive stuff added in the last 10ish years as far as processing sensor output to detect eyes/birds/motion/etc.
I suspect it's fairly challenging to implement since the LIDAR sensor doesn't operate through the lens, so you'd have to continuously align the depth map with the image to account for parallax; plus it's only useful for close-ish distances (since the lasers can't be too powerful) and can cause unwanted focus behavior with windows or reflections.
Modern systems like Canon’s Dual Pixel AF in bodies such as the EOS R5 are very direct descendants of that idea, just implemented on‑sensor with far more processing power.
Every time I see an article such as this, I beam with pride. (Pun intended).
Arguably more complicated than the anutofocus optics. The engineering of electromechanical cameras fascinates me.