This 24-70mmL is pissing me off. :(

Well, I've sent this thing to Canon twice and haven't seen one bit of a difference in the way it focuses.

It is backfocusing a bit on the extreme side at F2.8 on the wide end of the zoom range. Canon told me that if it's still not fixed to send the camera in with the lens.

The thing is I can't send my camera in because I need it for work.

I tested the L against my Tamron and 50mm 1.4 and here are the photos. None of the others had any back focus issues at all. It was too bright to point the 1.4 at bright sunlight so I took a shot of something that was a good distance away. Look how sharp my 50 is at 1.4.... =)

It's not just at a distance either. If I shoot a subject that's 8 feet away at 24mm/F2.8 it will focus on the background 90% of the time. Rarely will it lock onto the person's face.

These tests rule out my camera right? I mean my camera focuses damn perfect at 1.4 and doesn't have the same problem with my Tamron. Do I tell canon to shut up and send the lens again and demand they change it for another or what?

Canon 24-70mm @ 28mm F2.8
Canon 24-70mm @ 35mm F2.8
Tamron 28-75mm @ 28mm F2.8
Canon 50mm 1.4 @ F1.4

In case you kill that hosting here's the backup links:
Canon 24-70mm @ 28mm F2.8
Canon 24-70mm @ 35mm F2.8
Tamron 28-75mm @ 28mm F2.8
Canon 50mm 1.4 @ F1.4

So if you use the center focus point and focus right on someone's face, it'll focus past the person and beep and confirm a focus lock?

I don't see anything in focus with the link to the 50. I understand that it's 1.4, but I still see nothing sharp-ish. The Tamron definitely looks better, but let me ask you this. The focus in every one of those shots looks off. Are you quite certain your camera isn't backfocusing?

The 50mm shot is in focus. It's just "soft" at 1.4. The full shot shows tremendous bokeh with only the label of the propane tank in focus.

Now, I've been experimenting with the size of the actual AF sensor area around the middle focus point and discovered that it's really freaken big... I drew a diagram. If any contrast area (like the red strip of the canon lens box) touches the red lines it will snap into focus. The focus sensor seems to be ALOT larger than the little box. Do you think this area is too big when shooting a far away subject that's smaller than the area? Could it be locking focus onto the more contrasty foliage in the background?

I tested this lens out in a controlled environment at the studio with plane white background and a bunch of boxes and it would focus more accurately than it did in these tests. But those aren't real world scenarios.

Is it just that 20D/30D focusing sucks? My Tamron didn't have these problems though that's the thing.

I do notice this problem when using the lens "in the real world" and never with the Tamron after a year of having it.

I'm seriously confused now. Thoughts?

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Ronald S. Jr. wrote in post #2248321
I don't see anything in focus with the link to the 50. I understand that it's 1.4, but I still see nothing sharp-ish. The Tamron definitely looks better, but let me ask you this. The focus in every one of those shots looks off. Are you quite certain your camera isn't backfocusing?

I think a bit of the tire in the 50mm shot is in focus, but I can't tell for sure. It probably would've been better to take the same pic with the 50 as the other lenses. Those 24-70 shots are definately back focused, but it's hard to say what is causing it.

deadpass wrote in post #2248741
I think a bit of the tire in the 50mm shot is in focus, but I can't tell for sure. It probably would've been better to take the same pic with the 50 as the other lenses. Those 24-70 shots are definately back focused, but it's hard to say what is causing it.

They look as though they are focused on the leaves back behind the box, rather than the box.

Jackal wrote in post #2248356
I do notice this problem when using the lens "in the real world" and never with the Tamron after a year of having it.

Why did you change then out of curiosity? FTM? USM?

I will say, judging by your pics, it needs to go back to Canon again I think...

Tom W wrote in post #2248764
They look as though they are focused on the leaves back behind the box, rather than the box.

Yep.
A severe case of "leaf focus" there.

Ironically I "upgraded" to the L so I can get faster and better focusing. I shoot weddings and important events and my Tamron fails in comparison to the speed and quietness of L USM.

I've tested the lens out more today and it's ridiculous. It's being sent back to canon ASAP. I will tell them not to bother sending it back if they didn't test it for focus on subjects 10ft away or more. Pointing this at a chart might show "within specs back focusing" but when shooting further subjects this turns into literally focusing 30ft behind the subject. Also, this is a problem on the WIDE end of the zoom range....not at 70mm. The more you zoom out the worse it gets.

None of my other lenses do this so it cannot be my camera.

I can't even get the thing in focus at 24mm or 28mm on a subject that's 10 feet away if I use F4 or F5.6! Out of 10 tries 1 or 2 MIGHT be in focus.

The thing is I imagine them shooting a chart on a wall but not having any far background that shows it's obviously not focused on the chart but actually 30ft back.

Interesting...I can't say that I've ever seen a lens get the focus off by that much. Hopefully you'll get it resolved soon.

Ronald S. Jr. wrote in post #2248321
I don't see anything in focus with the link to the 50. I understand that it's 1.4, but I still see nothing sharp-ish. The Tamron definitely looks better, but let me ask you this. The focus in every one of those shots looks off. Are you quite certain your camera isn't backfocusing?

Ditto's, I was thinking exactly the same thing. None of them appear focused, but the Tamron is a little better.

Trust me the 1.4 focuses properly. I just shot a box with a ruler on the side. Focus is dead on with the 50mm. Never had any problems with my other lenses and they have been used since I've had my XT and now I have a 30D. As soon as I popped this 24-70 on for the first time I said "Uh oh...."

If you don't select the AF points you will never focus correctly, so it looks like user error as the leaves looked in focus.

I guess I should have stated I picked the middle focus point. In fact I have the middle picked 99% of the time.

I've been doing this for a good while man.....I'm not that dumb.

Jackal wrote in post #2249301
I guess I should have stated I picked the middle focus point. In fact I have the middle picked 99% of the time.

I've been doing this for a good while man.....I'm not that dumb.

I didn't mean it like that. When i started selecting the AF point my photography changed remarkably.

Try C-FN13-1.

Enables you to use the multi controller to select the AF Point on the fly.

C-FN13-2. Uses the Quick control Dial.

I use C-FN13-1. and C-FN4-1. plus a few others