topic Re: 5d mark III front focus problem in EOS DSLR & Mirrorless Cameras

5d mark III front focus problem

mo — Sat, 10 Jan 2015 21:49:37 GMT

my 5d mark III has a problem with front focus. I use only crosstype focus points but even cental one can't focus correctly no matter what lens I use. the problem is more significant further the subjet focused on is. tried different light conditions with the same result. Camera always front focusing significantly, so the suject is out of DOF all the time. tested lenses 50/1.4 and 24-70/2.8 L. problem persist in all AI modes (focus/servo). please could you provide any solution? thanks in advance

Re: 5d mark III front focus problem

TCampbell — Sat, 10 Jan 2015 21:54:42 GMT

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

Your 5D III will let you adjust some thing called "Autofocus Micro-adjustment" (AFMA). You can either do this gloally (for all lenses) or you can do it on a per-lens basis.

Although... if EVERY lens needs it... and needs a LOT of it... I think you might prefer to send the camera to Canon for correction.

Re: 5d mark III front focus problem

mo — Sun, 11 Jan 2015 00:57:32 GMT

thanks, I think that the problem is beyond AFMA capabilities, hope sending it back to Canon will solve this.

Re: 5d mark III front focus problem

TCampbell — Sun, 11 Jan 2015 01:32:07 GMT

Also... before you go through the bother to send this to Canon, make sure you've carefully tested it.

That means:

1) Camera on tripod (never hand-hold a camera for a focus test because if you sway or lean after it locks focus then you just invalidated the test.)

2) Pick a single AF point and make sure it's on your target. Don't let it use just any AF point. It'll gravitate to the AF point that can lock focus at the nearest focus distance (which could be mistaken for front-focus even though it's working exactly as intended).

3) Use a real focus test target - not a typical subject. You can use a commercial focus chart, or you can download one from the internet, print it out, follow the instructions, and do the test that way. Here's one I like: http://regex.info/blog/photo-tech/focus-chart

When testing, I like to run the focus all the way in (closest focus distance) so that the camera is forced to move the focus on the lens. Repeat a half dozen times and take notes of which shots started with focus all the way "in". THEN... manually run the focus all the way out (to infinity) and repeat that test a half-dozen times, while taking careful note of which frames were tested with the focus starting at infinity.

Import the images to your computer and analyze:

(a) is it missing focus ALWAYS or just sometimes?

(b) does it always miss focus in the same direction (e.g. always front focus? or random?)

(c) does it miss focus the same regardless of whether you started with focus "in" vs. with focus "out"? If focus misses different in one direction than in the other it could indicate some mechanical gear backlash (loose gears) in your lens.

Re: 5d mark III front focus problem

ebiggs1 — Sun, 11 Jan 2015 15:02:58 GMT

If you do decide to do MFA, make sure you are not real close to 'close focus' of the lens. Usually, 50 times the focal length of the lens is the rule.

Re: 5d mark III front focus problem

RobertTheFat — Sun, 11 Jan 2015 22:20:29 GMT

@ebiggs1 wrote:
If you do decide to do MFA, make sure you are not real close to 'close focus' of the lens. Usually, 50 times the focal length of the lens is the rule.

I'm not 100% sure what you're driving at; but it may be worth pointing out that the 5D3 allows two AFMA settings per lens, one at each end of the lens's range.

Re: 5d mark III front focus problem

KingEyre — Mon, 12 Jan 2015 10:04:28 GMT

Does it, Bob?

The 1Dx allows 2 settings but only on a zoom lens, at each end of the zoom range.

George.

Re: 5d mark III front focus problem

RobertTheFat — Mon, 12 Jan 2015 12:20:53 GMT

@KingEyre wrote:
Does it, Bob?
The 1Dx allows 2 settings but only on a zoom lens, at each end of the zoom range.

George.

Yes, that's what I meant. I don't know for a fact that the 5D3 doesn't let you set two values for a prime (I don't have any FF-compatible primes to test it with), but I'd have to assume that it works the same way as the 1DX.

Re: 5d mark III front focus problem

KingEyre — Mon, 12 Jan 2015 12:30:38 GMT

Yes, I'm almost certain it's the same as the 1 Dx, ie a setting for each end of a zoom....and that's also available in the 7D2.

George.

Re: 5d mark III front focus problem

KingEyre — Mon, 12 Jan 2015 12:34:18 GMT

I suspect you're best to return for a calibration check at a Canon centre, I'm sure you'll be able to find out where that is from someone else here, I'm only aware of the UK one!

EDIT that was a reply to the OP!!

Re: 5d mark III front focus problem

mo — Mon, 12 Jan 2015 12:37:21 GMT

thanks for all your comments, I'm gonna run the tests again as I was advised here and decide what options do I have.

Re: 5d mark III front focus problem

RobertTheFat — Mon, 12 Jan 2015 12:38:30 GMT

@KingEyre wrote:
Yes, I'm almost certain it's the same as the 1 Dx, ie a setting for each end of a zoom....and that's also available in the 7D2.

George.

Then that's another added feature of the 7D2. The 7D has only one setting per lens.

Re: 5d mark III front focus problem

KingEyre — Mon, 12 Jan 2015 12:45:13 GMT

Then that's another added feature of the 7D2. The 7D has only one setting per lens.

Bob
Boston, Massachusetts USA

Indeed it is, Bob, and it's surprising the difference with some lenses!!

Re: 5d mark III front focus problem

RobertTheFat — Mon, 12 Jan 2015 12:49:46 GMT

@KingEyre wrote:
I suspect you're best to return for a calibration check at a Canon centre, I'm sure you'll be able to find out where that is from someone else here, I'm only aware of the UK one!

EDIT that was a reply to the OP!!

Yeah, I figured that.

There are at least four Canon repair centers in the US. The one in Jamesburg, New Jersey is particularly convenient for me, since it's only a couple of miles from the route I use to visit my daughter in Philadelphia. Others are at Norfolk, Virginia, Chicago, Illinois, and somewhere in southern California.

Re: 5d mark III front focus problem

ebiggs1 — Mon, 12 Jan 2015 14:30:10 GMT

Bob from Boston,

I can read the Canon manual! Unusual?

1. Mount the camera and lens on a tripod. If the lens has
IS, shut it off.
2. Use Live View to manually focus on a stationary,
flat, high-contrast object that is at the center of the
viewfinder and parallel to the plane of focus. The
camera-to-subject distance should be no less than 50
times the focal length of the lens. For a 50mm lens this
would be at least 2.5 meters, or approximately 8.2 feet.
3. Focus the lens at its maximum aperture. Use Live View
magnification if necessary to assure that the image is
as sharp as possible.
4. Without touching the focusing ring or moving the tripod,
turn off Live View, and return the camera to One-Shot
AF, using only the center AF point.
5. Gently press the shutter button down halfway (or the
AF button if using back-button AF) while observing the
focusing ring or scale on the lens. It should not move.
If it does, take note of whether AF moves the plane of
focus closer (front-focus) or further away (back-focus).
If there is no shift in focus your lens is well-calibrated
and requires no adjustment.
6. To determine the correct amount of adjustment
necessary, take three sets of images at microadjustment
settings of -10 , 0 and +10; in other words,
three consecutive images at -10, three consecutive
images at 0, and three consecutive images at +10.
7. Examine the resulting images on your computer
monitor at 100% pixel magnification.
8. Take additional sets of test images at different
microadjustment settings if necessary until you can
determine which setting produces the sharpest image.
9. Register the corresponding microadjustment setting in
the camera.

Also, IMHO, what is thought to be miss-focus is actually user error and not camera/lens.

Re: 5d mark III front focus problem

RobertTheFat — Mon, 12 Jan 2015 15:45:12 GMT

@ebiggs1 wrote:
Bob from Boston,

I can read the Canon manual! Unusual?

1. Mount the camera and lens on a tripod. If the lens has
IS, shut it off.
2. Use Live View to manually focus on a stationary,
flat, high-contrast object that is at the center of the
viewfinder and parallel to the plane of focus. The
camera-to-subject distance should be no less than 50
times the focal length of the lens. For a 50mm lens this
would be at least 2.5 meters, or approximately 8.2 feet.
3. Focus the lens at its maximum aperture. Use Live View
magnification if necessary to assure that the image is
as sharp as possible.
4. Without touching the focusing ring or moving the tripod,
turn off Live View, and return the camera to One-Shot
AF, using only the center AF point.
5. Gently press the shutter button down halfway (or the
AF button if using back-button AF) while observing the
focusing ring or scale on the lens. It should not move.
If it does, take note of whether AF moves the plane of
focus closer (front-focus) or further away (back-focus).
If there is no shift in focus your lens is well-calibrated
and requires no adjustment.
6. To determine the correct amount of adjustment
necessary, take three sets of images at microadjustment
settings of -10 , 0 and +10; in other words,
three consecutive images at -10, three consecutive
images at 0, and three consecutive images at +10.
7. Examine the resulting images on your computer
monitor at 100% pixel magnification.
8. Take additional sets of test images at different
microadjustment settings if necessary until you can
determine which setting produces the sharpest image.
9. Register the corresponding microadjustment setting in
the camera.

Also, IMHO, what is thought to be miss-focus is actually user error and not camera/lens.

Ah, the "camera-to-subject distance". That's a welcome clarification. I don't believe you used that term in your earlier post.

Re: 5d mark III front focus problem

ebiggs1 — Mon, 12 Jan 2015 15:53:26 GMT

"If you do decide to do MFA, make sure you are not real close to 'close focus' of the lens. Usually, 50 times the focal length of the lens is the rule."

Hmmmmm...? OK.

BTW, off subject, a little, do you know Click and Clack, from Harvard Square?

Re: 5d mark III front focus problem

RobertTheFat — Mon, 12 Jan 2015 16:21:19 GMT

@ebiggs1 wrote:
"If you do decide to do MFA, make sure you are not real close to 'close focus' of the lens. Usually, 50 times the focal length of the lens is the rule."

Hmmmmm...? OK.

Well, I said I wasn't clear about what "real close to close focus" meant. Could have been an actual distance in feet or a point on the focusing ring.

BTW, off subject, a little, do you know Click and Clack, from Harvard Square?

I've listened to their program quite a few times, but I never met them. One of them (I forget which one) died this past year.

BTW, in this part of the world, MFA means "Museum of Fine Arts".

Re: 5d mark III front focus problem

ebiggs1 — Mon, 12 Jan 2015 16:17:17 GMT

Tom