5d Mark III AF issues... need help!

[pbfmini]

I bought this camera in march of this year and its never missed a shot. One week ago I noticed it was not focusing properly. I was in an indoor arena practicing low light so I didnt think anything of it. I have been adjusting settings all week now and CANNOT get it to focus properly.  Even resetting it to original settings did nothing for it.  I use a 70-200 f 2.8L almost always, however, last friday I experimented with both a 50mm and external flash.  I have a 2 day horse show to do this weekend, I need this this to work! has anyone experienced this or have any insight? TIA

[RobertTheFat]

Does the problem occur with both lenses?

[ebiggs1]

Going on the assumption you didn't drop or otherwise have a mishap with said 5D or the lens in the meantine?

Are you sure you "completely" reset the camera?  Sometimes this is not as easy as just pushing a button.

You are sure the lens is in AF and not MF.  Turn off IS for the moment.  AI-Servo is set to One Shot?  And you are saying both lenses exhibit the same behaivor?

Now have you tried to clean the contacts on the lens and camera?   If you have a local camera store maybe they will let you try a different 5D and/or lens to see which is not working properly.

Buy a new battery.

[RobertTheFat]

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@ebiggs1 wrote:

Going on the assumption you didn't drop or otherwise have a mishap with said 5D or the lens in the meantine?

Are you sure you "completely" reset the camera?  Sometimes this is not as easy as just pushing a button.

You are sure the lens is in AF and not MF.  Turn off IS for the moment.  AI-Servo is set to One Shot?  And you are saying both lenses exhibit the same behaivor?

Now have you tried to clean the contacts on the lens and camera?   If you have a local camera store maybe they will let you try a different 5D and/or lens to see which is not working properly.

Buy a new battery.

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I don't mean to single out the OP in this case, since I don't really know his sithation. But as a general observation I've been surprised at how many professional or semi-professional event photographers seem willing to wing it without a suitable backup camera. Even if one lives in an area where rentals are readily available, a failure can occur at any time - even in the middle of a shoot. A few years ago a regular poster on one of the Usenet newsgroups reported that he was shooting a wedding, and as he changed lenses on his 5D Mark I, the mirror popped out and fell on the floor! He wasn't the type to not have a spare, but what would you do if you were? Try to borrow a camera from the groom's father?

BTW, I'd be surprised if the OP's problem turned out to be due to the battery. The batteries used in the 5D3 (and in the 7D) are as reliable as any I've ever seen.

[cale_kat]

"....  CANNOT get it to focus properly."  Is it focusing at all? You suggest that it might not be focusing at all but the word "properly" means that it might be focusing but not the way expected or desired.

So, could you clarify that the lenses are set to AF? Could you tell us if it focuses at all? And if so, is it hunting for focus? Is it tracking? What isn't it doing? Details, please.

[TCampbell]

If it isn't doing what you want it to do, it's extremely beneficial to pinpoint exactly what it is doing.

To this end, you'll need to do some proper focus tests.  Real-world subjects are lousy for this because you cannot take specific measurements.  It's much better to use a test target.

I have a commercially made target (e.g. Datacolor "Sypder LensCal" or a "LensAlign").  But you can also get a test target that you can download and print from the Internet... such as this one:   http://regex.info/blog/photo-tech/focus-chart

The idea behind these is that you'll careful test conditions to isolate any other reason for the camera not focusing accurately.

Mount your camera on a tripod and now you know that the lens isn't moving and the camera isn't moving (so there's no blaming the photographer for not being steady).  

Place the test target at the prescribed distance (follow the instructions that come with the chart.  The distance will depend on the focal length of the lens.)

Select the focus point you plan to test (e.g. center point focus).  CAREFULLY algin the camera so the focus point being tested is on the high-contrast test-target position.

Make sure the camera is using "One Shot" AF mode (not AI Servo -- use "One Shot" for stationary targets such as this one.)

I deliberately de-focus the lens in one direction ... for example manually turn the focus ring to minimum focus distance.  There are two reasons for this... (a) I want to make sure the camera MUST adjust focus on each and every test) and (b) I want to know the direction that the camera had to move focus in order to achieve focus (e.g. if it was set to minimum focus distance then the camera must move focus out.   If it was focused to "infinity" then I know the camera must move the focus in.

Take notes so you know where focus started and which direction it has to move focus.

And since 1 sample does not make a trend... you'll need to shoot at least a half-dozen shots for each direction of your test.

The chart is laying back at an angle.  This means if the camera is "front focusing" you'll notice the areas on the chart that are a bit closer have better focus than those at the intended target position.  If it's "back focusing" you'll see the opposite.

If the camera CONSISTNTLY misses focus (say it's always just slightly back-focusing) then you can adjust this using the camera's built-in auto-focus micro-adjustments (see your manual).  

If it is NOT CONSISTENT then you have a different problem and the lens may require service.

The focus mechanism is mechanical... glass and other parts are moving to focus.  Gears can develop backlash or "slop".  This means if you move focus in one direction, then reverse to move focus in the other direction... a certain amount of free travel could occur before the lens actually starts moving again.

The bottom line... using good testing conditions to figure out exactly what your lens is doing.  It also means that if you do decide to send the camera and body in to Canon then you can describe the issue more accurately.

For further reading:  http://www.lensrentals.com/blog/2008/12/this-lens-is-soft-and-other-myths

[ebiggs1]

"... photographers seem willing to wing it without a suitable backup camera."

Bob from Boston,

I see it all the time.  But than there are pros and than there are "Pros".  There are a lot of folks that make a few bucks with their cmera and think that makes them a "pro" photographer.  It is quite one thing to do that as opposed to a guy that puts grocies on the table with his camera.

This and most other photography forums have people that may have shot a P&S for some years and than they buy a ?D or a even a ??D and overnight they are pros.  These persons are so very easy to spot.

But, hey, whatever floats your boat.  

BTW, I typically use four cameras at a wedding shoot. Plus my assistant will have another one or two cameras.

[cale_kat]

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@ebiggs1 wrote:

"... photographers seem willing to wing it without a suitable backup camera."

BTW, I typically use four cameras at a wedding shoot. Plus my assistant will have another one or two cameras.

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That's some serious boilerplate. 🙂

[pbfmini]

ok many things to cover and thank you all so much. i have def learned that the need for a backup is much greater than anticipated. i bought it in march and sold EVERYTHING i had to purchase the 70-200. i am by no means a pro, just an ammy looking to expand and learn.  this is why i believe it is me screwing up settings 😕 i was asked by my horse trainer to take pics at a riding clinic this weekend so of course i run into issues lol. soooo... same issue w both lenses. i reset to original/ out of box settings through the menu on camera. it cleared out everything i had done and i started from scratch. i have the camera set to ai servo for horseback riding lessons, i've tried every "case" setting in the menu, not much improvement. Right now what is happeneing is that i will focus on the horses eye during the lesson and the camera will focus on the side of where i've aimed. it is not every single shot- it is very hit or miss. i am super frusterated esp because i honestly believe it's something *I* did to the camera. i had my old camera (50d) for years and knew it front to back and the 5DM3 is quite different and it has definately been a learnig experience. i continue to take lessons and practice and learn but in the meantime i want to be able to take decents shots consistantly. up til this point this camera has not taken a bad shot.

[pbfmini]

also- the lens (70-200 f2.8L) was purchased used from B&h photo- they tested and graded it. the 50mm was bought new, it is the cheap $120 version, i just got it bc it was in stock at local Best Buy while i waited for other lens to come in mail. My next step is to take camera & lens to Murphys camera in Lville ky for testing OR send to canon. it has protection/ service plan thru Best Buy but I don't trust them 😕