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When will canon fix the focus issues with the 70D?

Photogirl55
New Contributor

I was "T.H.I.S." close to buying the 70D.  I have read WAYYY too many posts about issues with the focusing on the 70D.  How is Canon handling the issue?  I would love to buy this camera, but not willing to gamble with that much money.

223 REPLIES 223

Molybdo42
Frequent Contributor
@TCampbell
In my case, it's been very complicated to isolate the issue with test pictures (but I'm working on it). Because it looks like the wide black and white test targets are too easy for the sensor, the camera seems able to see that it is out of focus. But as soon as you do some subject photography, on less contrasted elements, it's completely out of focus.

The only measurement I could reliably make (with several lenses) was mapping the AF area.
Look at that post :
http://forums.usa.canon.com/t5/EOS/EOS-70D-focus-issue-question/m-p/97566#U97566

And answer my question : is it normal to have something so misaligned ? I haven't got a 7D or a second 70D to compare, so I have no clue.

More importantly, can Canon technicians fix that issue ? Because on the service manuals I found, I didn't see any procedure for AF sensor mechanical alignment. It looks like Canon just screws on the AF sensor and then does a software calibration wishing the manufacturing tolerances to be within specs. For the moment, my best explanation would be that if the sensor is too far or too close from it's ideal position, it might be trying to focus on a blurred signal, and it can only see extremely wide and well contrasted subjects.

Look at the pictures in these post, and tell me if that's how a camera's AF is supposed to work :
http://photography-on-the.net/forum/showpost.php?p=16974971&postcount=832

http://photography-on-the.net/forum/showpost.php?p=16969299&postcount=814

KeithR
Frequent Contributor

@Molybdo42 wrote:
Look at the pictures in these post, and tell me if that's how a camera's AF is supposed to work

Well, obviously not.

 

But in both of those shots, what has happened could have happened with any camera: in the first one, the AF point has overlapped the subject and - because there was more behind him for the AF to grab onto - has focused on the backgound clutter; and on the second one, it's just out of focus, which sometimes just happens - although given that the grass around the same plane of focus as the intended AF point is sharp, I'd put this one down to a thin DoF.   

 

Point being, neither of these behaviours is unique to the 70D, and in that very thread, for pretty much every "definitive" claim made by Scoobert, there are well-argued rebuttals.

 

As it happens, he might well have a squirrely camera (it happens), but the idea that the 70d is inherently flawed is just - to be blunt - ridiculous: believe me, I'd be at the front of the queue with proof, if that was indeed the case.

 

More to the point, I can post umpteen "proofs" that the 70D per se isn't "flawed" - but for some reason there's always this "selective reading" in these situations, where only the online evidence that "proves the probem" is ever cited.

 

Confirmation bias.

 

Funny, that..

 

Oh - and for completeness, "Mike55", one of the complainants on that thread admits he's using One Shot AF for his OOF bird shots!

 

Wrong AF mode! 

 

Molybdo42
Frequent Contributor

@ KeithR,

I can understand that you can be sceptical about focus issues on a dslr because indeed the cause is often behind the camera !

 

I know that some people have 70D with no issues, and you seem to be one of the lucky ones.

 

I'll go further and say that I'm almost convinced that the 70D issue doesn't come from a design error but from some in factory calibration or some camera components not being to spec. I'm talking about tens of microns here !

 

For example, I bought a focus screen with split prism on ebay for my 500D. Unfortunately, the prism was a little too thick and gave me some serious back focus issues in manual focus through the viewfinder. I solved that issue with a trick used in optics : simple 3M masking tape has thickness of rougthly 50µm, so, to adjust the total tickness, I "simply" had to use several layers of tape on the side of my focus screen until I could get the desired focus. So imagin, in the case of the focus screen, the distance has to be +-50µm from the ideal position to give correct focus ! That's the thickness of a hair !

 

WIth a margin for error so small, it's easy to understand that the AF sensor can be misaligned on several 70D. The origin could be that Canon has a problem with one of his calibration equipment or methodology, that's the fun part because this can result in a wide batch of defective cameras...

 

 

Now since the "give me proof" argument works both ways, I really want to know if my AF zones are normal, and if in my case the focus issues can come from a misalignment of the AF sensor. But up until now no one did the same test as me. Also for some reason, no one answered all my questions, do I need to rephrase them ?

 

 

Since you kindly proposed it could you please provide me some test pictures to map the AF points in your camera ? No need to assemble the images by yourself, put the pictures somewhere where I can download them. You can send them in low res jpeg (keep the raw files in case), I will merge them and post the results here.

 

 

Here's the testing procedure :

You'll need a computer screen, a mirror, the image file below with the black rectangle, a tripod, and if possible a remote.

It should take you one to two hours to map the 19 focus points (76 pictures) ; but for a quick assessment, I think you can limit yourself to the nine focus points located at the center. The goal is to move the black and white edge ntil the camera is barely able to focus.

http://i1262.photobucket.com/albums/ii604/Molybdo42/AF_areaTest-01_zps4366f833.png

 

Setup procedure :

  • Set the camera to manual mode single point focus, lens in autofocus mode
  • Set the file size to record full size raw and 5 megapixels JPEGs (S1)
  • Put the camera on a tripod
  • Open the picture with windows viewer, and zoom in until you can move the black rectangle across the entire screen
  • Quickly adjust the camera height position distance until you see nothing else except the black rectangle on white background,
  • Put the mirror flat against the lcd (you can use some 3M paper tape, the white one ; careful not to damage your screen)
  • Adjust the camera height, position, tip, and tilt ; until the image of the lens (visible in the mirror) is aligned with the center of the LCD (use LiveView). Tighten the tripod and check that the camera hasn't moved.
  • Remove the mirror

 

For each focus point :

  • With your mouse, while pressing several times the "AF-on" button (don't forget to configure the button to do auto focus) move the black rectangle towards the exterior of the focus mark until the focus can no longer be achieved (lens hunting)
  • Move back the rectangle a tiny bit until you can lock focus (use the green dot in the viewfinder to confirm the focus)
  • Take one picture, do the same for all four sides of the focus mark (you will see the focus area extends quite a bit
  • Repeat steps for all focus points

 

Important : for me, in order to analyze the pictures, the file numbering is important, so for each focus point take four (only four) consecutive pictures, don't mix them.

 

70Downer
Frequent Contributor

Hopefully somebody with a 70D or maybe even canon techs can help you Molybdo42.  Mine is on its way to canon virginia for this focus issue now or I would try to do what you want.

 

Also would like to appologies to TCampbell for calling him names while he was trying to do nothing but help.

Sorry sir.

ghstinshll
Occasional Contributor

Molybdo is the first person who's suggested an actual test that benefits anyone who thinks they have a focus issue... MAJOR KUDOS. You know as a new photographer, I find it interesting that the "old pros" (who obviously must be old because of how much of a curmudgeon they are) chim in on these things, all they do is rip on people and insult them. Heck, that's what I view as what's wrong witht he photography industry as a whole. Why would I even enter, when the public's perception is that "we" are all jerks? LOL

 

If "this kind of thing" is SOOO common, you "old pros", why don't you have a copy & paste doc readily available with suggested tests that the various people could use for help, rather than just being negative to everyone... 

 

There's a right way to say things, and there's a wrong way to say things... Try to use a little tact or simply don't respond. You're not doing people much good in the way you seem to be doing things right now. 

 

Molybdo42
Frequent Contributor

@ ghstinshll Thanks !

But I still don't know if this method works or not, no one (with a working or faulty camera) did the same measurements.

 

The only other test that I could think of would be to use Reikan Focal to measure the micro focus adjust values for all focus points. This allowed many users with faulty Nikon D800 to check their AF system :

http://www.falklumo.com/lumolabs/articles/D800Focus/SensorArray.html

 

Another step by step can be found here :

http://www.bythom.com/autofocus.htm

 

Now troubleshooting whether or not the AF sensor is misaligned is difficult without any equipment and it might need taking appart the camera (things that I don't want to do, so I sent mine for repair). For the moment my best guess would be that my camera's AF sensor is almost parallel to the imaging sensor, but too far or too close from it's ideal position. That would mean that the phase detect would try to work with a blurred signal, losing all details. For the moment that would explain why I can focus reliably on wide black and white focus targets (typically the kind of thing used when doing micro focus adjust), but not on sujects with lots of small details.

 

I found a description of the AF repair procedure for Nikon :

http://hifivoice.wordpress.com/2012/07/14/d800-autofocus-repair-overview/

In Canon's case, no idea...

 

Also, I don't know if camera manufacturers also calibrate the position of the AF sensitive areas and then disable unused pixels on the AF sensor strips (that would be evil...). I certainly know that this would be feasible because the 7D (not the 70D) has a spot AF mode.

pdqgp
Frequent Contributor

@Molybdo42 wrote:

Look at the pictures in these post, and tell me if that's how a camera's AF is supposed to work :
http://photography-on-the.net/forum/showpost.php?p=16974971&postcount=832

^^ The photographer had poor technique.  Seriously, to focus on the side of a subjects face like that is not how the photographer is supposed to work.  The AF Worked fine.   Not flaming the guy, but if he understood how the AF System functions, such a mis-fire would not have bene unexpected.   Innocent issue, but nonetheless not the camaras issue.  He should have placed that focus point squarely on the persons face.   Also, anytime the exact focus point you are targeting is small and perhaps the focus point extends outside the target, one has to be aware of the size of the focus points reach.  Again, you're studies are giving you a crash course on that matter. 

 

Even just today, playing around as I watered flowers, I was shooting with the intent to hit the center of a flower but the center was so small it fit completely inside the focus point.  One would think, great! it beeped, I nailed the shot.....nope, it focused on the white petals behind my intended target because of their greater contrast and the alignment of them with the edges of the focus square.  I didn't have enough DOF so at 100% it was slightly OOF.  Not a big deal as it was a playing around shot that the OOF was minor and wouldn't be seen at even 8x10 size. However, we are all pixel peepers anymore it seems, even me. 

 

I knew that was likely going to be the case as I've been there done that, so I simply flipped to Live View, zoomed to 5x insuring that not only was the focusing system targeting the center precisely but it allowed for me to visually see it do so better than just through the OVF.   The latter being a nice benefit to the 70D's focus system. 

Molybdo42
Frequent Contributor

Thanks for the answer ! It's exactly what I've done on first and second repair, in both I put a 4 pages letter explaining the issue. Now the conversation we had shows that I wasn't clear enough, if I need a third repair I'll try to modify my text. What posts were you occupying at Kodak and Panasonic ? This might help me in writting the letter differently.

 

 

Regarding the test shots of some poster showing focus issues, this is exactly the kind of situation I want to avoid with my test.

A lot of things can give focus issues. Most of the times the roadwarriors will always start to blame the user, then the lens/body combination who needs MFA, and they never blame the camera body because they never experienced something similar.

The guys who took the pictures already owned another camera body, their pictures might not be the best examples as they can lead to a lot of debate. But for his defence, most (if not all ?) photographers don't know the kind of software procedure the AF goes through when selecting what It should focus on. Does it focus on the nearest subject, or on the most contrasted, or on the one located in the center of the mark ? Those are questions I still need to ask myself. Maybe that the picture you pointed at would have focussed properly,maybe the AF system focuses on the closest widest subject (the face is closer and covers more than 4/5 the sensitive area, so I would expect to lock focus on that). I think that automatic AF point selection does that.

 

But, regardless what they were told, the affected users still "instinctivly" felt that something was wrong with their camera. Kind of like I did when I got the 70D. In my first pictures I couldn't understand why the camera can't focus. Also up until the 70D, I never payed too much attention to how AF works. In a sense, this 70D issue made me a better photographer as I now know what "crosstype" means (to show you how far I was)...

 

You unfortunately really need to experience that issue once to clearly understand what we are going through.

Molybdo42
Frequent Contributor

I'll add another piece of information, unlike older Konica Minolta 7D (http://photography-on-the.net/forum/showpost.php?p=16947213&postcount=719), Canon doesn't have three adjustment screws to level the AF sensor ! When assembling their AF sensor, they simply slap it on the mirror box and screw tight. For the 70D, the only possible adjustment is to use a screw to move the sensor to the left or right.

 

So in other words,Canon is counting on the manufacturing precision of their mirror box and their AF sensor to do most of the job ! But this method seems to work... most of the times.

 

I once had to adjust the position of a split prism focus screen (with several layers of thin tape), I can say that 50µm does make a huge difference, maybe the AF sensor has similar tolerance.

pdqgp
Frequent Contributor

@Molybdo42 wrote:

I'll add another piece of information, unlike older Konica Minolta 7D (http://photography-on-the.net/forum/showpost.php?p=16947213&postcount=719), Canon doesn't have three adjustment screws to level the AF sensor ! When assembling their AF sensor, they simply slap it on the mirror box and screw tight. For the 70D, the only possible adjustment is to use a screw to move the sensor to the left or right.

 

So in other words,Canon is counting on the manufacturing precision of their mirror box and their AF sensor to do most of the job ! But this method seems to work... most of the times.

 

I once had to adjust the position of a split prism focus screen (with several layers of thin tape), I can say that 50µm does make a huge difference, maybe the AF sensor has similar tolerance.


The reality is cameras from all makes are made differently.  However, all have a tollerance range when being assembled.   Canon is among the best as is Nikon.  Not knocking Konica, but there aren't many of their cameras shooting pro sports events.   If they had a lock on manufacturing tollerances and quality and accuracy, you bet that would be different.   Just saying....

 

In terms of adjustments, just look at when Canon introduced AFMA.  More issues came up now that every shooter thought they themselves could "fine tune" a camera / lens combo.   That's an entirely different story.   In the end, there are so many variables that impact the optics through the OVF that I wonder if it's even worth introducing such a feature.  However, the sale of cameras will likely drive that and today, not having AFMA wouldn't help sales.   And having the ability to tweak them won't change the need for users to fully understand the AF System in general.