Weird issue with my 6D. Please help.

[crandrewl]

Hi, I am having some weird issue with my 6D and I hope someone here can help.

The problem is that the AFMA does not work in "One Shot" and "AI focus" modes. It works in "AI Servo" mode. The weird thing is that if I keep pressing the AF-ON button (my focus buttton) as if in AI Servo mode, then AFMA works in both One Shot and AI Focus modes. You can tell if AFMA applied for that specific shot by reviewing the detailed info of the photo on LCD of the camera. I confirmed this by looking up the EXIF data with DPP.

The weirder thing is that when I examined the photo 100% crop, it seems like the AFMA was applied the whole time at the value I set at even though the detailed info on LCD or EXIF data showed that it did not apply.

No one (there were 4 different technicians) at the service center could figure out why and the lead technician left early that day (Fri, yesterday). So they said they will talk to him on Monday about this issue and will call me.

Does any one have any clue what is causing it? I think it's a simple camera software problem that just need to be reset - like computers where you can clean install the Windows. Is there something like that for Camera software? I tried resetting custom functions or camera settings, but it did not work.

Oh, one more thing I want to mention. The AFMA was working fine until just a few weeks ago. The problem started when I had an error message in FoCal software during fully automatic AFMA run where I had to force close the program. It may have been the FoCal that somehow did something to the camera software.

Thank you for reading my long post and any suggestions to fix this. By the way, my camera is still under warranty so the worst case I will get a replacement I guess.

Andrew.

 

[Mt Spokane Photography]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

Your title is really misleading. They did not know off the top of their head what's causing it, but have not yet had a chance to fix it.
Sometimes, they have to resort to changing out the main board when a processor issue causes strange happenings.

 

[crandrewl]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

No, they had it for 3 days and when i went there to pick it up, I found out that the problem was still there. I even left a note which I described the problem regarding this issue when I requested the service. I don't think they even read it. Repair paperwork just said they fixed the AF assembly.

 

[Loswr]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

Canon technicians 'cannot figure out' the issue, because there isn't one, per se.

AFMA is engaged during focusing. If you've set up back button AF, and aren't holding down AF-ON, the camera is not actively focusing (which, in fact, is one of the main reasons to use back button AF). In that case, the AFMA isn't recorded in the EXIF as shown during on-camera image review or by DPP. It's always shown when AF is assigned to the shutter button (since a half-press precedes a full release, with AF on the shutter button, the camera will always be focusing when the shot is taken). In AI Servo, it's always focusing, too. If you try to view the selected AF point in DPP, you'll see an analogous issue.

Side note: the camera actually does write the actual AFMA value into the Metadata even with back button AF. In addition to the AFMA value, there is another EXIF tag for AFMA Status (or something like that) and it can have values like 0 (which is interpreted as OFF), 1 (ON), and 2 (UNKNOWN). In the scenario you describe, the 5DIII apparently writes a 2, which most software (including DPP, apparently) seems to interpret as OFF and doesn't display the AFMA value. Image editing software and many EXIF viewers don't even show the AFMA Status field.

The bottom line is that your selected AFMA is being applied to the shot, even if the EXIF doesn't show it. If you want to convince yourself, select a value that's way off (e.g., if it needs + something, set -20) and take a couple of shots in One Shot using back button AF as you normally do, and compare them to shots with the correct AFMA set - you'll see the -20 shots are misfocused, and the correctly set shots are sharp, even though none will show an AFMA in the EXIF.

 

[crandrewl]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

Your title is really misleading. They did not know off the top of their head what's causing it, but have not yet had a chance to fix it.
Sometimes, they have to resort to changing out the main board when a processor issue causes strange happenings.

Okay, I updated my title to be fair.

 

[crandrewl]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

Canon technicians 'cannot figure out' the issue, because there isn't one, per se.

AFMA is engaged during focusing. If you've set up back button AF, and aren't holding down AF-ON, the camera is not actively focusing (which, in fact, is one of the main reasons to use back button AF). In that case, the AFMA isn't recorded in the EXIF as shown during on-camera image review or by DPP. It's always shown when AF is assigned to the shutter button (since a half-press precedes a full release, with AF on the shutter button, the camera will always be focusing when the shot is taken). In AI Servo, it's always focusing, too. If you try to view the selected AF point in DPP, you'll see an analogous issue.

Side note: the camera actually does write the actual AFMA value into the Metadata even with back button AF. In addition to the AFMA value, there is another EXIF tag for AFMA Status (or something like that) and it can have values like 0 (which is interpreted as OFF), 1 (ON), and 2 (UNKNOWN). In the scenario you describe, the 5DIII apparently writes a 2, which most software (including DPP, apparently) seems to interpret as OFF and doesn't display the AFMA value. Image editing software and many EXIF viewers don't even show the AFMA Status field.

The bottom line is that your selected AFMA is being applied to the shot, even if the EXIF doesn't show it. If you want to convince yourself, select a value that's way off (e.g., if it needs + something, set -20) and take a couple of shots in One Shot using back button AF as you normally do, and compare them to shots with the correct AFMA set - you'll see the -20 shots are misfocused, and the correctly set shots are sharp, even though none will show an AFMA in the EXIF.

Thank you for your explanation. Why none of the technicians there did not have that info when I asked them about it? Any way, like I said in my original post, it did seem like the AFMA was applied the whole time whether EXIF data shows or not as you explained. And now I understand it. So, it is normal and I don't have to worry about it?

One question. Why do you keep holding the AF-ON button while in One Shot mode? I understand that you do that in AI Servo mode to continually focus. But in One Shot Mode, What's the benefit of that except to have the AFMA value recorded in EXIF data?

 

[Loswr]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

One question. Why do you keep holding the AF-ON button while in One Shot mode? I understand that you do that in AI Servo mode to continually focus. But in One Shot Mode, What's the benefit of that except to have the AFMA value recorded in EXIF data?

The only time I care is when I'm taking shots to use for a manual analysis in FoCal, since the software won't recognize the AFMA otherwise. Else, there's no reason to do so.

 

[crandrewl]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

One question. Why do you keep holding the AF-ON button while in One Shot mode? I understand that you do that in AI Servo mode to continually focus. But in One Shot Mode, What's the benefit of that except to have the AFMA value recorded in EXIF data?

The only time I care is when I'm taking shots to use for a manual analysis in FoCal, since the software won't recognize the AFMA otherwise. Else, there's no reason to do so.

Thank you for your answer. By the way, how do you know all this? ;D ;D

 

[Marsu42]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

Image editing software and many EXIF viewers don't even show the AFMA Status field.

Oh my, great piece of information in the post above, thanks, Neuro!

To contribute something useful (I hope): The most complete way I know to get exif data is exiftool (it's a perl script, but there are standalone files for Mac & Windows). The big advantage is that it's able to decode just about all obscure "Maker Notes" as plain text, and that would include afma'ish information.

For Lightroom, there's a simple exiftool wrapper ui "Metadata Viewer", but the most helpful is the free "Exif Meta" plugin which reads any exif information you want like afma or "focus points locked on" and enabled you to display/sort according to this in LR

http://www.sno.phy.queensu.ca/~phil/exiftool/
http://regex.info/blog/lightroom-goodies/metadata-viewer
http://www.robcole.com/Rob/ProductsAndServices/ExifMetaLrPlugin/

 

[crandrewl]

Re: Weird issue with my 6D that even Canon technicians cannot figure out why.

Image editing software and many EXIF viewers don't even show the AFMA Status field.

Oh my, great piece of information in the post above, thanks, Neuro!

To contribute something useful (I hope): The most complete way I know to get exif data is exiftool (it's a perl script, but there are standalone files for Mac & Windows). The big advantage is that it's able to decode just about all obscure "Maker Notes" as plain text, and that would include afma'ish information.

For Lightroom, there's a simple exiftool wrapper ui "Metadata Viewer", but the most helpful is the free "Exif Meta" plugin which reads any exif information you want like afma or "focus points locked on" and enabled you to display/sort according to this in LR

http://www.sno.phy.queensu.ca/~phil/exiftool/
http://regex.info/blog/lightroom-goodies/metadata-viewer
http://www.robcole.com/Rob/ProductsAndServices/ExifMetaLrPlugin/

Thank you for the links. "Exif Meta" seems useful. I will try it.

 

[ahab1372]

Bear in mind that software can display and interpret EXIF data in different ways - sometimes even different versions of the same software.

I have been using ExifTool embedded in GraphicConverter. With version 8.68 (embedded in GraphiconConverter 6.7) I get the following:
AF Micro Adj Active : Unknown (2)
AF Micro Adj Value : 3

for the same picture, with version 9.39 (embedded in GraphicConverter 8.8.2) I get:
AF Micro Adj Mode: Adjust by lens
AF Micro Adj Value: 3

As you can see, the Exif tag and the value are interpreted differently. I actually believe that this particular tag used to be somewhat boolean 0 = OFF and 1 = ON, and that Canon then changed it to have three possible values, corresponding to settings on newer cameras: 0 = OFF, 1 = "All by the same amount", 2 = "Adjust by lens"
Some software might still expect the old pattern, or even look at different tags altogether, resulting in meaningless interpretations. Bottom line is, the camera uses AFMA regardless of the button being pressed or not, but it mitt not be obvious to the software trying to interpret the Exif data.

 

[ahab1372]

Oh and then different cameras might behave differently, to make things even more confusing. I remember a thread a while ago where Neuro's 1DX seemed to write different values than my 5D mark iii. Not 100% sure though