I'm having (10D) focus problems only with 24-70 f/2.8L !

[sparty314]

I've had my 24-70mm f/2.8L lens for about 2 months, and I have never been blown away by the image quality. The images I took with it never seemed to stack up to images with my 50mm f/1.8 and 70-200mm f/4L.

Recently, I took a whole bunch of group photos at f/4.0 because I wanted the (relatively close) background out of focus. When I view the images at 100%, the images just are not in focus.

By default, I have my 10D set to One-Shot mode and use the center focus point only. For each of these group photos, I refocused each time on a high contrast area of one of the people's faces. And yet, in most of the photos, the plane that is in focus is clearly about 2 feet behind the plane of my subjects.

This got me curious, and I went back and looked at other images I've taken with that lens. More times than not, they simply aren't focused to the correct distance. Usually, the grass (or other object) a few feet behind the subject is in sharp focus, and the subject is soft. I'll admit that I fequently use the old "focus and recompose" method when I don't think that the exosure metering will be thrown off.

So, I did a quick search here and read about "back focusing" or "front focusing." I did a quick non-scientific test, and it reaffirmed my fears--my camera seems to autofocus just fine with the 50mm f/1.8, but it is off with the 24-70.

I placed a yardstick at a 45 degree angle from the plane of the back of the camera and I balanced a card with a target on it in the middle of the yardstick (parallel to the camera back). I placed the camera about 8 feet away from the target, and I took 10 pictures using autofocus to focus on the target (refocusing each time) at f/2.8. Instead of the 18" mark being sharp as I would expect, it was the 11" or 12" mark in every single image!

I repeated this same test with my 50mm lens, and it performed very well. Most of the images had the 18" mark the sharpest, and a few were an inch or two on either side.

I called Canon support, and the representative was very helpful. I explained the problem (as I have here), and he asked me to repeat my camera/lens combination. He put me on hold as he went out and hooked up a 10D to a 24-70 lens and came back. I could hear him clicking a few pictures in the background, and then he said, "I'm not getting that problem here." This made me a little suspicious because I had explained to him that you really needed to view the pictures on a monitor at 100% size to notice it--plus, I really didn't think that there was some universal problem with 10Ds and 24-70s.

Anyway, he told me that, since I noticed the problem only with that one lens and not with my 50mm or 70-200mm, the problem was likely with the lens. Since the lens is covered by warranty and the camera is not, he told me to send it in to Canon Factory Service, and that's what I did a few days ago.


Does anyone have any thoughts or experiences that might shed some light on my problem?

I am thinking that it's likely that I'll also have to send in my camera. But, if that then fixes the problem, won't my focusing be off with my other lenses?

[cc10d]

I had similar problems with my lens. I tried it on my 10d, my wifes drebel, and my A2E. All produced soft images on autofocusf f4 and f2.8. I returned the lense within 2 weeks of purchase for full credit. The lens did ok manually focused or at 5.6 usually and 8 and 11 were ok. I bought the lens to get the wide f stop features and felt if I did not have those with autofocus why be out the price? So I shoot away with my 28-135 IS and wish I had the 24 or the sharpness of the 24-70 manually focused. But I get ok pictures with the 28-135. Did like the well focused shoots from the 24-70, nice quality. but I also like autofocus.

I will be very interested in how your lens is when you get it back from Canon. Hope you will post the results.

Chuck

[drisley]

Yes please, post your outcome.
For a lens that costs $2000 CDN, you should expect ALOT more from it.

[Mike H]

Since you are using the focus-recompose method, I would suggest that you read the article at the link below. You might find it very helpful.

Mike H

http://visual-vacations.com/Photography/focus-recompose_sucks.htm

[RichardtheSane]

Since you are using the focus-recompose method, I would suggest that you read the article at the link below. You might find it very helpful.

Mike H

http://visual-vacations.com/Photography/focus-recompose_sucks.htm

That is an interesting article, I might test the theory or at least see if there is anywhere else that can confirm it (I get bored doing tests ;) )

All the physics of it seem sound, but I don't know enough about how lenses work to be 100% sure!

[DocFrankenstein]

http://visual-vacations.com/Photography/MiscImages/Focus-RecomposeSucks.jpg

Red line indicates where you want the [camera] :roll: to be focusing

Green one indicates where it actually focuses :?


Male oriented camera with a nice AI :lol: 8)

[sparty314]

Thanks for the replies and the link to the discussion of the focus and recompose issue. I don't think that it is enough to explain why most of my images are bad--I'm not usually moving the camera all that much during the recompose step.

Plus, as I've said, I am not experiencing these problems with my other lenses--just the 24-70!

[ShootTechPan]

I have the EXACT same problem, and only with the 24-70mm 2.8L. Other lenses are spot on. And this problem is consistent on five different Canon bodies... So I wouldn't let them tell you to send in your 10D as they'll probably charge you to "fix" your 10D and then it may have focusing issues on your other lenses.

I too, was sometimes not impressed with the lens's sharpness, and performed some focus tests. It's razor sharp... about a 6-12 inches behind the target (depends on the distance of the target.)

I'm eagerly awaiting your results with Canon's service.

[sparty314]

ShootTechPan,

Did you contact Canon about your problem with the lens?

[ShootTechPan]

I haven't yet as I have been too busy, but it's a nagging problem that I do want to fix before that warranty runs out.

[mrtreacle]

I had the exact same problem, out of around 100 shots, ALL of them were back focused. So I took it back to Samy's, got a 70-200L 2.8, and couldn't be happier.

[natalka]

I have this exact same issue with this exact same lens, but I am sending my camera and lens in together to CPS for service. They seem to have kinda fixed the back focus on another lens, the 16-35.

I now own two 24-70L's, one for me and one for my assistant, and the newer 24-70 doesn't seem to have this issue.

I guess I'll see in tw weeks when I get my equipment back.

Nata

[Mark_Cohran]

You know, I have nearly the opposite problem---my 28-70 2.8L works great with the 10D, but I have minor back focus issues with my 70 - 200 2.8L. But, what I have determined is that I have some lenses that work great in combination with the 10D and some that work not so great. So, knowing this, with the not-so-great lenses, I'm much more careful with my composition, dof, and recomposing.

[ShootTechPan]

I had the exact same problem, out of around 100 shots, ALL of them were back focused. So I took it back to Samy's, got a 70-200L 2.8, and couldn't be happier.

Ugh i would totally take it back if I could, but it's been nearly a year now and way past return time.

Besides, the 70-200mm doesn't solve my problem of needing a quality standard zoom.

[blinking8s]

I think the main focus problems with the 300d and 10d and the newer lenses is a cross between it being a good but not amazing AF system, and dependency on the AF, not paying attention to your DOF range with how you are shooting. Most of the time it is not the cameras fault

[CyberDyneSystems]

Interesting...

I noticed just recently that the older 28-70mm f/2.8L I have has a lot of trouble focusing...

It is the only lens I own that when I hit the AF button the image in the viewfinder looks noticeably "off"


Very often I find myself reaching for the manual focus ring to "tweek" it.

This is most noticeable on the 10D... I'll have to try it on the MkII to see if the problem is still noticeable on another body.

Every other lens I have used on my 10D seems to AF just right...

[ShootTechPan]

CyberDyneSystems, looking forward to your findings as I'm also curious how the new autofocus system deals with various lens issues.

[ShootTechPan]

I think I'm going to send in my 24-70mm and 70-200mm 2.8L IS in to Canon this week. No wonder Canon lenses only come with 1 year warranties :P

[sparty314]

I got my lens (24-70 f/2.8L) back from the Canon Factory Service center in New Jersey within 8 days of sending it out. There was only a one word description of what services were performed--"overhaul."

I was disappointed with that because I had written a detailed description of the problem and what I had done. That aside, however, I am very pleased with their service.

The lens seems to be *much* better. I have only taken about 100 photos so far, but I have not noticed that any of them exhibit the back focus problems that I had before.

Honestly, I'm surprised that I was able to get this resolved so quickly and without sending my camera!

[robertwgross]

The focus problem can be caused by a lens that is out of calibration, or it could be caused by a camera body that is out of calibration, or it might be caused by user error. Of these three, rule out two and then get the third one checked.

---Bob Gross---

[Mitch]

Good advice, Bob.

I just ordered a 24-70 from B&H today for receipt on Monday. Can hardly wait. I have two 10D cams. I have written on focusing problems before, because I had focusing problems with both cameras and with all four of my other lenses. Sent them all back to Canon for fixing. Got them back, and the severe front and back focusing has been fixed. Now I only have slight front focusing on most of the lenses, and one of the combinations of a specific lens and a specific 10D focuses righ on. I am happy and I believe that this is as good as it will ever get. I don't think that these Canon products, the 10D, and the Canon lenses are ever guaranteed to be calibrated to be spot on. I believe that if they are spot on, it's just plain luck. I don't think that if your equipment just happened to be calibrated perfectly that they would hold that calibration very long. I think that is just the nature and the limited capacity of the equipment, particularly the 10D.

My equipment front focuses about one inch from four feet away at wide apertures. I am satisfied with that. Since I know that, I shoot with settings that define a depth-of-field that will keep in focus that part of the subject that I want, and, with enough DOF to compensate for the front focusing.

Bottom line, before concluding that a piece of equipment is inferior or doesn't perform well because of an inate incurable design deficiency, presume instead that it is not calibrated sufficiently and send it to Canon for an "overhaul". Also, don't presume just because you got something new that it is properly calibrated, in fact, I would presume that it is not. When I get my 24-70 this Monday, I am going to test its focusing accuracy before using it on a job. If it focuses properly out of the box, I will consider myself lucky. If not, I am going to drive it 6 miles to the Canon Irvine, CA repair center immediately.

[ShootTechPan]

Got it back. Lens was very clean, probably cleaner than when I bought it new in the store. Focus seems to be spot on now (the focus-recompose fallacy is a good thing to keep in mind. Also the fact that there is twice as much DOF behind the focal plane as there is in front is good to keep in mind when testing.)

Canon stated that they "replaced PCB [PC board/ECU?] assy main. adj/best focus point. projection test. cleaned elements. ck/adj/lub all functions to factory specs." It looks like there is a 6 month warranty on factory work (for the same problem only).

I think I'm done testing. Time to start shooting!

[moucher]

I have also noticed back focusing problems with the 24-70 2.8 L as well - not always, but a significant amount of time that has to be far more than user error. I would like to know how much Canon charged for the overhaul/calibration (mine is out of warranty).

[photoshooter]

i own a Tokina 24-70 2.8 i would use it for a boat ancher if it didnt cost so much i bought a sigma 24-70 2.8 100% IMPROVEMENT if any ones interessted id sell it

[SeanH]

With out a doubt it's the lens. I'm on my 3rd one and I am still not fully trusting it. I don't know what it is with that lens??? Seems quite a few people have the same problem, IMO somebody should start asking Canon some questions. Seems to me this lens has got some problems. It IS a very sharp lens.......when it focuses correctly, which my guess is at least 10-20% LESS than any other lens I own.........And like I said, I'm on the 3rd one. I would love to dump this thing but I can't find anything to replace it.