Canon Patent Application: Major Defocus improvements

[Canon Rumors Guy]

One of the problems that mirrorless cameras have is major defocus. This is when you attempt to focus on the subject with the lens completely out of focus. There’s not enough contrast for the camera to determine just how far it needs to move the lens to reach focus on the target. On DSLRs, Canon

See full article...

 

[neuroanatomist]

Hope this is implemented in the R1.

 

[Del Paso]

And once again, Canon prove they are not innovative at all...

 

[vangelismm]

The problem is well explained, but what is the proposed solution?

 

[Del Paso]

One of the problems that mirrorless cameras have is major defocus. This is when you attempt to focus on the subject with the lens completely out of focus. There’s not enough contrast for the camera to determine just how far it needs to move the lens to reach focus on the target. On DSLRs, Canon

See full article...

Could be even more important for wire-focusing macro lenses, where manual focusing assistance only works when camera is fully active.

 

[Marphoto]

Home run and I can’t wait to see it in action.

 

[Richard CR]

The problem is well explained, but what is the proposed solution?

a better look at what is defocused to try and determine the quickest way of getting close and determining actual focus.

there's really nothing they can do in silicon to resolve the issue, especially with big fast tele's...

A thought experiment, throw a 400mm F2.8 out of focus as much as possible. that's what your AF has to look at to determine focus. It's of course a hot soupy blurry mess. but from that the AF has to try to make an estimate. Thus why it racks in and out. but they are thinking of two speeds depending of what they call a reliability factor. Not really a solution, but perhaps better.

I haven't seen too many DPAF patent applications dealing with this, and of course, this is probably more a concern for Canon on an R1, etc camera, which they would expect to have the big fast tele's being used.

@Del Paso Macro is certainly another problem domain where out of focus can make it impossible to determine focus distance.

 

[Quack]

Having focus limiter settings in the menu would be a big help, and essentially eliminates major defocusing issues. No new patents or technology needed. The Olympus (now OM Systems) cameras have had the ability to set a minimum and maximum distance for years now. It is the single biggest reason I use the OM-1 over my Canon cameras for Birds in Flight.

 

[koenkooi]

Having focus limiter settings in the menu would be a big help, and essentially eliminates major defocusing issues. [..]

In the same vein: more automation for focus stacking, just have the user set the overlap percentage and begin/end. There's a lot more DPAF can be used for to make taking in-focus shots more straight forward, let's hope Canon will start implementing that and adding to all camera bodies.

 

[TonyNorthrup]

This is a serious problem in need of a solution, so I'm glad they're thinking about it.

With the problem of finding, say, a flying bird with a 600 f4 when the lens is pre-focused at the wrong distance, my proposed solution has always been for the camera to detect a field of nothing but bokeh and shut the aperture down while selecting a moderate distance, essentially bringing everything into focus enough for the photographer to identify and frame the subject while the camera fine-tunes the focus enough to open the aperture back up. Could be a little jarring in the viewfinder but it's gotta be better than just staring at bokeh while the lens hunts which is how it works now with mirrorless cameras when you aren't pre-focused.

 

[AJ]

Hope this is implemented in the R1.

But isn't the patent for DSLRs?
Nevermind, I read the article again. The patent is for firmware to be implemented on mirrorless cameras and not the yellow AF sensors for DSLRs

Having focus limiter settings in the menu would be a big help, and essentially eliminates major defocusing issues. No new patents or technology needed. The Olympus (now OM Systems) cameras have had the ability to set a minimum and maximum distance for years now. It is the single biggest reason I use the OM-1 over my Canon cameras for Birds in Flight.

I think the idea is to get AF to the point where focus limiters are no longer needed.

 

[Maximilian]

Would be great to see those features handling major defocus soon.

 

[Anon]

I wonder if Panasonic has anything up their sleeves for this issue. Before adding pdaf to their cameras they worked a lot with the DFD system, so they might have some experience with this particular problem.

 

[koenkooi]

I wonder if Panasonic has anything up their sleeves for this issue. Before adding pdaf to their cameras they worked a lot with the DFD system, so they might have some experience with this particular problem.

DFD is basically using contrast based AF to emulate DPAF. Canon doesn't need to emulate DPAF, they have the real thing The patent discussed here is about how to handle extremely defocussed scenes, not how to handle regular defocussed scenes.

 

[Bahrd]

The problem is well explained, but what is the proposed solution?

Reading between the lines, I suppose they make an educated guess (based on say, a miriad of already taken and analyzed pictures). I am however surprised they don't patent a transient setting an aperture to f/16 or f/22... Maybe they will use it in 800/11 and 600/11 exclusively?

DFD is basically using contrast based AF to emulate DPAF.

I thought it exploited asymmetry of a PSF's shape with respect to BF and FF.

 

[AlanF]

Having focus limiter settings in the menu would be a big help, and essentially eliminates major defocusing issues. No new patents or technology needed. The Olympus (now OM Systems) cameras have had the ability to set a minimum and maximum distance for years now. It is the single biggest reason I use the OM-1 over my Canon cameras for Birds in Flight.

Rarely have problems with AF on BIF with the RF 100-500mm on the R5 - maybe the narrow f/7.1 has been the answer.

 

[DhlcadR6]

Having focus limiter settings in the menu would be a big help, and essentially eliminates major defocusing issues. No new patents or technology needed. The Olympus (now OM Systems) cameras have had the ability to set a minimum and maximum distance for years now. It is the single biggest reason I use the OM-1 over my Canon cameras for Birds in Flight.

I'm 100%with you. Manufacturers should opt for focus limiter customisation in body. It's the most costt-effective way to control the AF behaviour. And once user grasped the sense of focus distances needed. Switching to MF is going to be easy

 

[David - Sydney]

Having focus limiter settings in the menu would be a big help, and essentially eliminates major defocusing issues. No new patents or technology needed. The Olympus (now OM Systems) cameras have had the ability to set a minimum and maximum distance for years now. It is the single biggest reason I use the OM-1 over my Canon cameras for Birds in Flight.

In theory, I should use the physical focus limiter for my underwater macro work using my EF100/2.8L but I prefer to have full focal range as sometimes a distant subject can also be interesting.
Sometimes the lens will focus on particulate giving a completely out of focus image which is annoying. The only solution to start focus again is to put my hand in front of it and start focusing again. Once focused, it will then search for subjects again.
Menu focal range limits would be a useful option with a custom button or custom menu. Although it could be slower than my focus reset option using my hand.
Having a menu option to switch from manual to auto AF could also be useful. I always need to check after housing assembly that it focuses okay as there is no way to move the manual/AF switch when under water!

 

[Sean C]

I\'m surprised they haven\'t used aperture control in conjunction with DP phase detect focus. If you\'ve got a big white that\'s 100% so that the phase detect can\'t read direction/amount out of focus, then stop down until the sensors do read well, focus in the indicated direction and then open the iris as the subject comes into focus. The lens can stop down very fast, so it\'d be an easy improvement. i.e. if the autofocus we\'re used to is about to hunt, stop down progressively while reading the focus sensors; if you get a useable reading do a standard \'direct\' focus and go back to wide open as the lens arrives at proper focus so fine tuning works.
Is there something that\'d keep that from working?

 

[justaCanonuser]

I\'m surprised they haven\'t used aperture control in conjunction with DP phase detect focus. If you\'ve got a big white that\'s 100% so that the phase detect can\'t read direction/amount out of focus, then stop down until the sensors do read well, focus in the indicated direction and then open the iris as the subject comes into focus. The lens can stop down very fast, so it\'d be an easy improvement. i.e. if the autofocus we\'re used to is about to hunt, stop down progressively while reading the focus sensors; if you get a useable reading do a standard \'direct\' focus and go back to wide open as the lens arrives at proper focus so fine tuning works.
Is there something that\'d keep that from working?

Interesting idea! Indeed, that could give the system a bit more microcontrast by augmenting the depth-of field and therefore improve the guessing in which direction it should try to focus first. But I can't imagine that Canon's engineers did have that idea, too. Maybe there is another problem we do not see here...