Canon adds focus breathing correction support to f/2.8 and f/4 RF zoom lenses via firmware

koenkooi

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I have yet to see this feature demonstrated anywhere, but it's an intriguing concept for amateur and lower-budget corporate video makers if it works as advertised without artifacting or other weirdness.
Kai shows it briefly in his preview, from 6:23 till 6:33:
 
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koenkooi

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Still hoping for Canon to develop a firmware correction for the RF 100 macro's focus shift issue.
I'm hoping for that as well, but reports on other fora imply that not every copy has the same amount of shift. So far I've been lucky enough to be the weakest link when using the RF100, the shift hasn't been an issue yet.
 
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Del Paso

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I'm hoping for that as well, but reports on other fora imply that not every copy has the same amount of shift. So far I've been lucky enough to be the weakest link when using the RF100, the shift hasn't been an issue yet.
Good for you, but not very reassuring in terms of assembly and machining tolerances...
 
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Canon Rumors Guy

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I'm hoping for that as well, but reports on other fora imply that not every copy has the same amount of shift. So far I've been lucky enough to be the weakest link when using the RF100, the shift hasn't been an issue yet.
Memories of the first few years of the EF 50 f/1.2L.
 
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Still hoping for Canon to develop a firmware correction for the RF 100 macro's focus shift issue.

+1

Given Macro users are a minority compared to users of 70-200 and other L lenses not surprised that 100mm L isnt getting any updates(though I would love to see Canon release non SA 100mm L macro).
 
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Interesting to see what FW can do.
Would like to hear from RL experiences here.


Thanks for that, but didn't really get a good impression from that video.
I remember watching some preview of Sony or Fuji camera which had focus breathing compensation and was demonstrated and explained well(though none of R6 II videos covered that feature in as much detail).
 
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illadvisedhammer

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I'm hoping for that as well, but reports on other fora imply that not every copy has the same amount of shift. So far I've been lucky enough to be the weakest link when using the RF100, the shift hasn't been an issue yet.
Absolutely, so a sophisticated fix would let the camera perform an AFMA like ritual on itself, like I think some DSLRs did with live view, but a simpler fix would be to add a mode where the camera can be set to focus stopped down or partly stopped down, like focus at f8 for an f13 shot
 
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Still hoping for Canon to develop a firmware correction for the RF 100 macro's focus shift issue.
Focus shift isn’t the same as focus breathing, of course, but it could also be compensated for in firmware.

Focus breathing correction on the R6II works in movie mode only, presumably by adjusting the video crop slightly to compensate.

A few of the more recent Sony alpha and FX cameras offer the feature, as well.
 
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No, SA adjustment is a feature, focus shift is an issue . And if Canon can correct focus breathing, they sure could correct via firmware focus shift.
Focus shift is a 'feature' (meaning a distinctive attribute) of the RF 100mm Macro lens design. Not a desirable one, but a feature nonetheless. Apparently Canon felt the design tradeoff of going to 1.4x magnification was worth the consequence of focus shift. While it would be possible to address it with firmware, it's a more difficult proposition than correcting focus breathing.
 
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Canon Rumors Guy

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No, SA adjustment is a feature, focus shift is an issue . And if Canon can correct focus breathing, they sure could correct via firmware focus shift.
The EF version of the 100mm IS macro had focus shift, it just wasn't as obvious. I don't believe focus shift can be corrected in firmware. Canon has in the past evolved lenses to reduce the effect, the EF 50mm f/1.2L being an example.

I don't recall ever seeing a firmware update that corrected focus shift. It's 2022 though, maybe it's in the works.

Most, if not all fast lenses have focus shift to some degree.
 
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I don't believe focus shift can be corrected in firmware.
One simple way (pointed out above) that would work on MILCs is to have the lens focus at the selected f/stop instead of focusing wide open then stopping down (since it's the latter that causes the shift). That would be quite easy to implement in firmware. It could be implemented as an option, perhaps only being applied at focus distances >0.5x magnification.

Alternatively, the focus distance of the lens could be shifted slightly based on the selected aperture. The problem with the latter approach is that the magnitude of the shift varies with both the extent to which the aperture changes relative to wide open and the distance to the subject, and the latter is very difficult for the camera to estimate at macro working distances.
 
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koenkooi

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The EF version of the 100mm IS macro had focus shift, it just wasn't as obvious. I don't believe focus shift can be corrected in firmware.[...]
Provided the focus shift is the same in all copies, it's a matter of making a 2D lookup table that maps focus distance to aperture and applying that. In this "high speed RF mount with fast, extra pins" world, this could conceivably be done on the body.

Canon has already done something very similar for the RF70-200 front focussing issue, so I'm of the opinion that there isn't a technical reason stopping this, but a variance or political issue instead.
 
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