Eye tracking Autofocus?

[Tony S]

Had the Elan IIe and found that I could manually compose my images with a fixed focus point much more accurately than the tracking feature, so I disabled it and would never want to see it again.

 

[minicoop1985]

As I was looking through the viewfinder of my 7D today, I was wondering about this feature. I'm kinda surprised it hasn't come back. Was a neat idea in its time, that's for sure.

 

[Skelrad]

I had (still do) the Elan IIe as well. The eye controlled focus points worked great for me, and when I started looking at dSLRs I was shocked they didn't use some form of that technology. I can see how the feature would bug some people, but I settled right in with it and used it the vast majority of the time. I would definitely consider another camera that had it.

 

[jeffersonite]

I could see a couple of problems...

The precision you can get from eye-tracking is probably not as high as you would like. If the tracking is off by a single millimeter you might end up with a completely incorrect focus.
Another problem is that the eye can move really fast which I imagine could make the system lag behind or even get lost sometimes. This is probably fixable though so not too much of an issue I guess.
The last problem with the principle itself is the focus distance when multiple objects are behind each other. You could be shooting through branches, a fence or slightly dirty windows. How would the system determine what to focus on? It's basically impossible to see where your eye is focused. Even if you can track your eye position up to a 1000th of a millimeter, this problem is probably still going to make the system unreliable.

Besides these problems with the principle I see another technical problem which is the placement of the system in the camera. To be able to really track the eye position you'd need to have the eye-tracking camera more or less right in front of the eye, it won't be an option to place it next to the viewfinder because you just wouldn't be able to always see the pupil. Theoretically this could be done with an infrared-mirror and infrared lighting on the eye, but it would both make the viewfinder part of the camera a lot more complex and might result in a slightly darker viewfinder too because there would be an extra element between your eye and the image.

I don't know... It might be possible to get some sort of system going but it would not be perfect and probably cost quite a lot too.
I'll stick with the current systems for now.

I think you misunderstand how Canon's eye focusing worked: you use your eye to select the autofocus point on the viewfinder, your hands holding the camera aim where that AF point lands in the scene.

 

[Judobreaker]

Yes that is how it works. It simply determines which focus point is used, instead of fiddling with the arrow keys on the camera body. It only needs to triangulate your pupil and corneal reflection, which is trivial. Not figure out how far your eye is focused.

And almost none of these technical barriers described would be an issue at all. Keep in mind this already WORKED something like 10-15 years ago. And eyetracking technology has improved much much faster than the number of focus points has increased.

For example, @Judo: the precision and accuracy of eye tracking systems today is sufficient to measure a smooth trajectory of your eye DURING a saccade. In other words, while your eye is flitting from one point to another, the system can take multiple samples and plot out a smooth curve, which can be used to infer information about your cognitive biases and subtle attentional allocation to objects off to the sides of that trajectory (they will "pull" the curve closer or further from a basic trajectory). This is fairly easy affordable technology to do even that nowadays. And position wise I believe they are simply built into the viewfinder inside. And yes they probably use infrared LEDs, which cost like $1.20.



If it is something that people just don't give a crap about though, like Derrel suggests, well then okay. Seems pretty awesome to me though. Say goodbye to ever focusing and recomposing again.

I know eye-tracking systems do actually work pretty accurate nowadays, I've worked with several eye-tracking systems for some projects involving the measuring of hand-eye coordination. Sure they work and sure they are (to some extent) affordable, there's a slight problem with these systems though... They are rather big for a camera.
They're probably issues that can be dealt with though.

I think you misunderstand how Canon's eye focusing worked: you use your eye to select the autofocus point on the viewfinder, your hands holding the camera aim where that AF point lands in the scene.

Well yeah, that's sort of how I imagined it. The problem is that I'm used to my D800 having 51 of those points which would make accurate tracking a bit of an issue.

I'm not saying a system like this is completely impossible... I'm just doubting that the practical use would make up for the costs and implications.
As was said: The idea probably has been discontinued because of a lack of interest with the buyers, which seems like a perfectly reasonable situation. ^^