Is my 5DII autofocus system defective?

Not expecting the 5D to autofocus like a 1 series or a 7D... but I would hope it was slightly improved over my 2+year old 40D...

kurt765 wrote in post #9161110
Or is it just this bad?

My 5DII is an upgrade to my 40d I had previously. What I've found with the 5DII is that the autofocus system is terrible in comparison. It hunts a lot. Take for instance the following scenario.

Camera is on a tripod.
Lens has no IS.
Subject is static (mountains don't move fast enough to be seen with the naked eye)
AEB is on
Using cable release
All AF points enabled

Push button - camera completely refocuses before firing. Takes perfectly in focus scene, throws it out completely and focuses back again.
Push button for second AEB exposure. It does the same thing. It's like it completely forgot what it was doing.
Repeat, etc. etc.

I can try to direct it to a single AF point but it will do the same thing. This morning it seemed to error completely at one point by throwing the lens to close focus instead of infinity and refusing to try the other direction until I had manually focused it almost there. WTF?

I used to own a 20d, and this is theoretically the same AF system feature wise, right? The 40d could fire off a few dozen shots in the time it takes the 5D to focus 3 times on a static mountain.

What am I doing wrong? I knew the AF system was going to be a downgrade from the 40d but I did not expect it to just plain SUCK.

Aside from this I'm pretty happy with the new camera, since I do landscapes mostly...

-K

Have you spoken to Canon service?

crotter wrote in post #9162594
Not expecting the 5D to autofocus like a 1 series or a 7D... but I would hope it was slightly improved over my 2+year old 40D...

I would not expect an improvement over your 40D.

The center point of my 5D was better (more accurate more times) than my 40D's was as is the 5DII's. That was noticeable right away.

i think calling into canon and speak with them will probably give you the best result.

We need a sample.

kurt765 wrote in post #9161110
Or is it just this bad?

My 5DII is an upgrade to my 40d I had previously. What I've found with the 5DII is that the autofocus system is terrible in comparison. It hunts a lot. Take for instance the following scenario.

Camera is on a tripod.
Lens has no IS.
Subject is static (mountains don't move fast enough to be seen with the naked eye)
AEB is on
Using cable release
All AF points enabled

Push button - camera completely refocuses before firing. Takes perfectly in focus scene, throws it out completely and focuses back again.
Push button for second AEB exposure. It does the same thing. It's like it completely forgot what it was doing.
Repeat, etc. etc.

I can try to direct it to a single AF point but it will do the same thing. This morning it seemed to error completely at one point by throwing the lens to close focus instead of infinity and refusing to try the other direction until I had manually focused it almost there. WTF?

I used to own a 20d, and this is theoretically the same AF system feature wise, right? The 40d could fire off a few dozen shots in the time it takes the 5D to focus 3 times on a static mountain.

What am I doing wrong? I knew the AF system was going to be a downgrade from the 40d but I did not expect it to just plain SUCK.

Aside from this I'm pretty happy with the new camera, since I do landscapes mostly...

-K

When you say "completely refocuses", do you mean that the lens focus moves far or does the camera just make a small forward/back movement to focus?

Is the subject well-lit? The outer AF points are known to be a bit less sensitive in low-light than on other cameras and since they are not cross-type, have some trouble with verticle contrast boundaries compared to the 40D. The center point, however, is very accurate and works in situations at least as dark (if not darker) as the 40D.

trancerem wrote in post #9162586
well, i do not know why you feel disappointed, cause 5d mark II is around for few months and tons of reviews are avaible, and all specify that this is not a fast-focus camera. of course is precise, but not for hot-action-shots.

Put it in AI Servo, select the center AF point with the invisible "assist" points activated, and you'll find that it does focus quickly. In one-shot, it chooses precision over speed.

Tom W wrote in post #9163421
When you say "completely refocuses", do you mean that the lens focus moves far or does the camera just make a small forward/back movement to focus?

Is the subject well-lit? The outer AF points are known to be a bit less sensitive in low-light than on other cameras and since they are not cross-type, have some trouble with verticle contrast boundaries compared to the 40D. The center point, however, is very accurate and works in situations at least as dark (if not darker) as the 40D.

By "completely refocuses" I mean that it moves the focus far away before coming back. It's not a small movement.

I have not yet talked to Canon service.

I expected the autofocus system to be worse than my 40d since the 40d has all cross-type sensors and the 5DII does not. I won't be able to do any more testing till this weekend. I wanted to see if there is something wrong before calling Canon. I have a bunch of shoots coming up and don't want to be without my new camera.

-K

Actually, I don't think there is anything wrong with your camera and doubt that Canon service will be of any help.

You might be able to get the camera to stop "hunting" and "refocusing" with each shot by setting Custom Function III: 1 to "1", which turns "Focus Search off" "when AF is impossible". I don't know if this will work or not.

One quite certain way to prevent the focus from changing each time you go to take a shot is to use Custom Function IV: 1 and set it to "2". That assigns AF function to only the AF-On button, separating it completely from the shutter release button.

It takes a short time to get used to this method of focusing, but would certainly solve your problems once and for all. For lack of a better term, I call it "thumb focusing". A lot of Canon sports shooters use this method because it puts them back in full control of the focusing system. Similar setup can be done on any Canon body, altho the Custom Functions and buttons used might vary a little.

Using the camera as you are, with it on a tripod, with mirror lockup, and with a release switch, with thumb focusing you will have to set focus first by pressing the button on the camera body (after which it will remain focused. And with static subjects like mountains you can recompose the image if you wish... for example if using just the center AF point and not wanting your primary point of focus exactly centered.)....
Then do the shutter release action(s). You should be able to set drive to sequential shots, with AEB, and just let the camera fire off several shots... But - you are correct - when using Mirror Lockup you can't use a continuous drive mode. The camera simply acts like it's in single drive mode, since you have to press the shutter release twice in order to take each shot... once to lift the mirror, the second time to take the shot.

If you choose to set up thumb focusing, you might also want to know that on 5D2 you can optionally consider swappng the function of the AF-On and * buttons with Custom Function IV: 2, set to "1". I do this because the * button is larger and, IMO, better placed. I focus my lenses a lot more often than I use AE-Lock, so the larger, more prominent button makes sense for me. On older cameras that didn't have the AF-On button (which I still have a few), or if using a BG-E2/E2N with 40/50D (because the grip lacks the AF-On button), the only choice was to assign thumb focus to * and give up the ability to switch AE-Lock on/off on the fly. (You had to dive into the Custom Functions to enable or disable AE-Lock... So I usually just left it set to AE-Unlocked.)

The thumb focusing method works fine with either AI Servo or One Shot... In AI Servo you normally hold the button down continuously as you track subjects. In One Shot you just press the button until you get the focus confirmation, then release it. Oh, and if you are tracking a moving subject and using AI Servo continuously, but the subject is momentarily moving behind some object that might mess up focus, you can briefly lift off the button, then reacquire the subject on the other side of the object.

Thumb focusing also works fine with either a single AF point (on 5D/5D2 with or without expansion points enabled... Custom Function III: 7, set to "1"), or with Auto Selection from All AF Points (which leaves it up to the camera exactly where it will focus, something I'll usually try to avoid).

I switched to using the "thumb focusing" method a few years ago and would never consider going back to the old way!

Note 1: I think it fairest to say that the 5D2 (and 5D classic) AF system is different from the 40D, not necessarily better or worse. It's designed for different methods of shooting, and to accomodate the larger image area. 40D is designed more as an action camera, and 9 AF points cover a pretty large portion of the image area without a lot of gap between them. 5D/5D2 is designed more as a studio/"large format" camera, perhaps for more deliberate shooting styles, less action shooting, and has a lot more image area to cover with 9 AF points, which leaves large gaps between them (thus the 6 expansion points).

While the 5D2 has nine visible AF points like your 40D, yes, only the center one is the full cross type while the 40D enjoys all nine as cross type. The center point on 5D2 is about twice as sensitive as the other points. However, something it has that your 40D doesn't: 5D/5D2 also have 6 "hidden" points that surround the center point... So actually has a total of 15 AF points. The hidden ones are the AF Expansion points mentioned above. The expansion points really help with moving subjects, but are only effective in AI Servo focus mode... Not in One Shot. Of course, you can use either One Shot or AI Servo with a static subject like a mountain. You can see the active "expansion" points indicated, when used, while reviewing images with Canon's softwares.

Note 2: You also might experiment with Live View mode... I'm not sure how that would work combined with MLU and AEB.

I've never heard of this thumb focusing technique that you describe. I may give that a shot. Part of the motivation for this thread is that my 40d never does this. When a given focus point is set, it will not try to hunt if the subject is still in focus. The corresponding point will just blink red for a sec to indicate that the point is focused. I'm not used to having to focus, then set the lens to MF to keep it from hunting which is what I've had to do with this camera. The AF system is easily the single most disappointing aspect of the 5DII even if it was working properly, IMHO. Canon historically doesn't spread out AF points to cover a full frame sensor. Only the crop cameras have widespread points. Maybe that's changed but I seem to recall that the 1Ds series AF system is virtually identical to the 1D series, meaning that the points are clustered towards the center of the frame in the FF 1ds compared to the 1D. This relationship seems to be the same with the 5D / 5DII. If you were to crop in on the image in the 5DII viewfinder I think you'd find the af points pretty much line up with that of a xxd series camera. But anyway. I knew all this going in. I did not expect it to do this hunting crap though.

Re: Note 2: LIve View is effectively mirror lockup since the mirror is up and the sensor is on. I think AEB functions with live view.

-K

crotter wrote in post #9162491
Is the 5D2 autofocus really a downgrade from my 40D?

I havent received my 5D2 yet... but If thats true I'm slightly disappointed...

Yes. A silly decision by Canon for such a pricey camera, but its true.

But what the OP describes is not at all normal.

versedmb wrote in post #9166560
Yes. A silly decision by Canon for such a pricey camera, but its true.

But what the OP describes is not at all normal.

Actually, I think Canon made a decision to not upgrade the AF system on the 5D2 in order to keep the price as low as possible. If I recall correctly, it was intro'd at $2700, which was about $500 less than the 5D when it was intro'd three years earlier. 5D2 would have cost more if it also had an upgraded AF system. In addition, they might not have had any new system far enough along in the works yet (and were probably still reeling a bit - or even gun shy - from the fiasco over the 1D3's AF system issues, be they real or imagined).

Keep in mind that the AF system has to work as part of a complete package... A more sophisticated AF system probably would have needed more processor power, which could mean either slowing down an already fairly slow frame rate even farther, or cutting down sensor resolution, or adding a second processor at additional cost.

For how they anticipate the camera being used primarily, the 5D2's AF system is adequate. It would be nice to see it upgraded in the future. Or tweaked with any firmware fixes they might do in the meantime.

There's another post discussing why FF cameras are a whole lot more expensive to manufacture than crop sensor cameras.

Sony has had one or two breakthroughs in the last year or two, that's allowed them to produce CMOS sensors more cheaply. They supply Nikon's sensors. And Sony has their own FF camera priced under $2000, but it's probably a loss leader... To get people to jump to their system.

crotter wrote in post #9162491
Is the 5D2 autofocus really a downgrade from my 40D?

I havent received my 5D2 yet... but If thats true I'm slightly disappointed...

Its a huge downgrade from the 40D AF if you ask me. i think the 40D is all cross type. 5DII has one Cross type point in the middle and the rest arent very good.

Joel

Nothing like reviving a dead horse. But.....

I came across this thread looking to confirm my findings on the 5D2's focus points. I figured the centre was a cross type. The two directly above and below the centre point appear to be horizontal type sensors (focusing on vertical lines) and the other 6 are vertical type sensors. I find it handy to know how the focus points are configured.

I guess we are spoiled by the focus points in the xxD series bodies. I cannot comment on the 1D or rebel series bodies at this moment. I have not had a chance to play with either of them.


PS: Why does POTN log me out so soon? Is there a setting I can change to keep me logged in?