p.71 #1 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Alan321 wrote:
Now that is an impression that my 40D gave me. It focused on edges that were nowhere near the chosen AF sensor. However, it's hard to imagine how it can happen. BTW there was no cure for my 40D - Canon reckoned it was within spec.
p.71 #2 · ['NEW Fix' UPDATE!] - MkIII AF still broken
apdieb wrote:
... I am becoming more and more convinced that the AF sensors are locking on objects with more texture/contrast in the frame regardless of the point chosen. Seems like for me no matter what adjustments I make, the tendency (not always) is to lock on the grass in front of the subject (if it's in the frame). This is with center point manually selected and AI_Servo. I have no idea why grass is my major contributor...but all I know is that when it's predominately in the frame, my camera wants to grab it out in front...regardless of my AF point being squarely and consistently on the subject.
All these adjustments seem to be helping...but I am convinced there is something inherently wrong with the way the AF is interpreting the scene and we're having to make adjustments to fool the camera into actually misfocusing based on where it thinks it should be vs. where we want it.
...Show more →
The more I use the camera, the more the odd AF tracking errors seem to fit exactly that pattern, and grass, trees, or shrubbery are usually involved. It doesn't require sports action, either. An outdoor wedding can have a great expression lost because it's OOF. I did the last one with my 1DII and 1DIII. It was raining, very dim light, and the MkIII caught some great stuff under very difficult circumstances. I suppose the MkII was given less demanding tasks (indoors and under a canopy, using flash), but at any rate, it nailed the focus on every shot. I just want a perfect camera, that's all. Is that really too much to ask?
To be fair, I've occasionally missed follow-focus shots at weddings with the MkII in past years, and it's hard to compare the two cameras directly for that.
p.71 #4 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Photon wrote:
The more I use the camera, the more the odd AF tracking errors seem to fit exactly that pattern, and grass, trees, or shrubbery are usually involved. It doesn't require sports action, either. An outdoor wedding can have a great expression lost because it's OOF. I did the last one with my 1DII and 1DIII. It was raining, very dim light, and the MkIII caught some great stuff under very difficult circumstances. I suppose the MkII was given less demanding tasks (indoors and under a canopy, using flash), but at any rate, it nailed the focus on every shot. I just want a perfect camera, that's all. Is that really too much to ask?
To be fair, I've occasionally missed follow-focus shots at weddings with the MkII in past years, and it's hard to compare the two cameras directly for that....Show more →
p.71 #5 · ['NEW Fix' UPDATE!] - MkIII AF still broken
OK, so I finished the first round edit on 1795 cycling images from Sunday, and 30% were unusable due to AF issues, only a small amount of those user error. As is typical with this camera, other than different subject matter and differing lighting conditions, I have no idea how I can shoot kids soccer on Saturday and have a 94% hit rate, and shoot cycling on Sunday and have a 70% hit rate. I'm admittedly more experienced with soccer, but in many ways cycling is easier and more predictable to shoot.
p.71 #6 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Alan321 wrote:
Now that is an impression that my 40D gave me. It focused on edges that were nowhere near the chosen AF sensor. However, it's hard to imagine how it can happen. BTW there was no cure for my 40D - Canon reckoned it was within spec.
- Alan
My cameras are 1D and 40D. Neither show that phenomena.
p.71 #7 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Jeff wrote:
OK, so I finished the first round edit on 1795 cycling images from Sunday, and 30% were unusable due to AF issues, only a small amount of those user error.
p.71 #9 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Oddly enough I have started to use AI Servo more now than ever before. I used to use One Shot whenever it was possible just because I liked to control the focus. Now though I am finding I can save a lot of time by just keeping it in AI. Sometimes while moving and shooting at the same time I get some OOF shots but I am not sure if that is a flaw.
p.71 #10 · ['NEW Fix' UPDATE!] - MkIII AF still broken
momv630 wrote:
Me too! I have since given up on AI Servo. I keep it at One Shot and it works just fine (fast moving subjects or not)
EXACTLY what I see in AI Servo mode as well (post sub-mirror fix). Interestingly, One-Shot accuracy has improved dramatically since the fix, but AI Servo not at all.
p.71 #11 · ['NEW Fix' UPDATE!] - MkIII AF still broken
marchantron wrote:
EXACTLY what I see in AI Servo mode as well (post sub-mirror fix). Interestingly, One-Shot accuracy has improved dramatically since the fix, but AI Servo not at all.
Correct! I haven't used AI Servo at all since I've had 2 fixes. I seem to be in a happier place now
p.71 #12 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Alan321 wrote:
Now that is an impression that my 40D gave me. It focused on edges that were nowhere near the chosen AF sensor. However, it's hard to imagine how it can happen. BTW there was no cure for my 40D - Canon reckoned it was within spec.
- Alan
It's probably totally wrong, but could it be because when the camera starts off from an unfocussed state each AF sensor receives information from all over the frame and not only from where the sensor is pointed at? Some sort of "phase mixing" occurs when strong patterns outside of the sensor area prevail and affect the camera's decision where to focus.
p.71 #13 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Jeff wrote:
AI Servo at medium tracking sensitivity, center-point with left-right assist enabled. Looking forward to some cycling shooting today, we'll see how it does with faster subjects.
Regardless, this is more like it.
-Jeff
Jeff, since following this thread closely from time to time and trying various things, two weeks ago I decided to take all pics for awhile on AI SERVO as I had almost always used 1shot. I was pleasantly surprised. My percentage OOF didn't change much BUT second and following shots in a sequence InFocus went way up. Still not impressive but better. After two weeks of this I read your above note and the LR Expand is the way I set all my previous 1V and 1d's - I tried it again. I changed the sensitivity down to, C.Fn III 2,center; and left, right assist, C.Fn III 8,1. My last 600 shots testing these settings show a noticeable inprovement. Thanks for all your related experiences.
Good Shooting !!
p.71 #14 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Hello,
I recently bought a 1D MkIII (s/n out of the affected range) and have shot a few thousand frames since then (primarily wildlife, birds; with a 500mm and 1.4 TC). Everything seems to work perfectly, except… Ai Servo. What I’ve observed so far (especially regarding the first point I’m very interested to hear from other MkIII owners if this behaviour is normal, thanks):
- Center AF point only, pointing on a stationary subject, stable support (tripod or bean bag) --> the AF is continuously adjusting back and forth by a significant amount even if camera and subject aren’t moving at all. This results in a lot of out of focus images (even at f8), as with wildlife you haven’t always the time to switch to One Shot mode. (The MkIII white paper states: " Even if AI Servo AF is used to focus on a still subject, stable control is enabled so that the lens drive isn’t constantly fine-tuning. If the subject starts to move, the focusing responds immediately to detect the subject constantly.”).
- The slower a subject moves the less reliable is the AF tracking. I had rather good results at 10fps testing on cars driving towards me on a motorway at 120km/h, but with 4fps and birds slowly flying, walking or swimming towards me, more than half of the images are out of focus. Again, this is in contrast to what the white paper says (“During low-speed continuous shooting, the subject distance can change significantly between shots. The slower the continuous shooting speed, the more the lens is driven between shots to detect the subject. Thus, subject tracking is more precise.”). And, if the there are only slightest changes in the subjects speed and/or the light/contrast is not optimal (overcast sky, no direct sunlight), AF tracking performance is even worse.
- In (very) low light, after sunset, Ai Servo on a stationary subject doesn’t work at all, One shot does work though. A 40D used at the same time did work in Ai Servo.
Currently I feel that the MkIII isn’t worth the money; of course I will continue testing Ai Servo performance before sending it in, weather forecast fortunately is good for the coming weekend…
p.71 #15 · ['NEW Fix' UPDATE!] - MkIII AF still broken
I have the same exact problem and mine was repaired in mid december. When I get back to the states in a month I will ship it back out Also, on a side note I have this one pixel that is intermittently hot regardless of exposure.
p.71 #16 · ['NEW Fix' UPDATE!] - MkIII AF still broken
lermite wrote:
the AF is continuously adjusting back and forth by a significant amount even if camera and subject aren’t moving at all. This results in a lot of out of focus images (even at f8),
Lermite, I noticed this as well, but I have found that changing CF III-4 (AI Servo AF Tracking Method) to 1 (Continuous AF track priority) results in significantly more stable performance with static subjects. It also seems to help to disable AF point expansion (CF III-8). This is with firmware 1.1.3.
My experience at this stage is still pretty limited (I only recently received a body on loan from CPS--serial number 512xxx). So I don't have a handle on how this setting affects performance with moving subjects, but you may want to give this a try.
I expect that a reasonable argument could be made (by Canon) that AI Servo is for moving subjects only, and is not intended for general AF use. I personally use One Shot a lot, but I know lots of shooters who never take their bodies out of AI Servo.
Some of the prosumer bodies have an intermediate AF setting that begins in One Shot but switches to Servo if subject movement is detected. It seems this would be desiable behavior in many instances.
p.71 #18 · ['NEW Fix' UPDATE!] - MkIII AF still broken
Colin Key wrote:
I do not understand this statement at all.
Colin
CF III-8 turns on AF point expansion which enables "helper" AF points that surround the selected AF point. In my (admittedly limted) experience, leaving this at the default setting--disabled--seems to improve stability for static subjects. YMMV.
p.71 #19 · ['NEW Fix' UPDATE!] - MkIII AF still broken
With my 20D I pretty much left it in servo all the time - no problems.
Doing that with my 1DMkIIIs resulted in lots of hunting when tripod mounted and shooting a stationary subject. Also resulted in lots of OOF shots as did One Shot.
With my 1DsMkIII I use servo most of the time and the hunting problem is gone. So are the OOF problems in both Servo and One Shot.
Canon told me that that the hunting was my fault for leaving it in Servo. Therefore I can deduce that my 20D and 1DsMkIII are broken.
p.71 #20 · ['NEW Fix' UPDATE!] - MkIII AF still broken
garyvot wrote:
Lermite, I noticed this as well, but I have found that changing CF III-4 (AI Servo AF Tracking Method) to 1 (Continuous AF track priority) results in significantly more stable performance with static subjects. It also seems to help to disable AF point expansion (CF III-8). This is with firmware 1.1.3.
I have set the CFs as you suggest. AF point expansion seems only useable for flight shots (birds against the sky or another background with less contrast than the subject), for larger birds/closer range when the central circle in the viewfinder is more or less covered by the subject or for very fast tracking action when the background blurs completely. But I haven't had the opportunity yet to test this properly.
garyvot wrote:
I expect that a reasonable argument could be made (by Canon) that AI Servo is for moving subjects only, and is not intended for general AF use.
This is of course a reasonable argument (One Shot is certainly more precise for static subjects). But when my 20D most of the time can correctly focus on a still subject in Ai Servo and Canon is stressing the ability of the 1D to stabilize Ai Servo when pointing on a static subject in there own white paper, I expect it to work...
Hrow wrote:
With my 20D I pretty much left it in servo all the time - no problems.
Same here. That's one reason I'm so surprised about the behavior of the 1D.
Hrow wrote:
Canon told me that that the hunting was my fault for leaving it in Servo. Therefore I can deduce that my 20D and 1DsMkIII are broken.
Canon states in the 1Ds MkIII white paper that the AF system is almost identical to the 1D. As you own both cameras, it should be easy to prove them wrong and get the 1D repaired, no?
("The state-of-the-art AF sensor in the EOS-1Ds Mark III is shared with the EOS-1D Mark III. The AI SERVO AF algorithm has been optimized to match the continuous shooting speed of the EOS-1Ds Mark III, approximately 5 fps. Also, due to the full-frame CMOS sensor, the Area AF coverage with respect to the viewfinder is slightly smaller than with the EOS-1D Mark III. The AF speed and predictive AF performance are the same as with the EOS-1D Mark III. All other AF-related specifications not mentioned here are also the same as the best-inclass EOS-1D Mark III."
I did the last one with my 1DII and 1DIII. It was raining, very dim light, and the MkIII caught some great stuff under very difficult circumstances. I suppose the MkII was given less demanding tasks (indoors and under a canopy, using flash), but at any rate, it nailed the focus on every shot. I just want a perfect camera, that's all. Is that really too much to ask? 
