EF 24-105 4L IS- Focusing problems

Hello all.

First of all thanks for this great forum. I've been reading messages on it for a long time but I just never took the time to sign up. Well, now I had too because I have some strange problems with my new Canon EF 24-105 4L Lens...

I bought it ca. 10 days back and actually I would be very happy with it: from 35-105 extremely sharp images, great colors, ... but here it goes. I noticed that all pictures in the range 24-35mm are unsharp. A Focus Test Chart confirmed it: bellow 40mm or so the lens has an extreme front-focus. I can quite easily reproduce the problem:
a) I focus on an object exactly 3,5m away at 105mm - focus is ok and the scale on the objective stops at 3,5m
b) Now I zoom to 50mm and focus on the same point - as expected the focus stays were it is at 3,5m.
c) I zoom to somewhere between 24mm and 30mm and refocus the same point: now the focus stops at ca. 1,5m (which is wrong).

I could repeat the same test and got similar results no matter how far the object I was focusing on was distant (i.e. actual distance 1,5m - at 24mm the lens is focusing on 1m, for an object 30-50m away it is focusing at ca 3,5m...). I always use the central focusing point only.
I also took the lense to a local photo-shop and tried it on another body (at home I have a 350d). Same behavior. They said that this is certainly a problem of the lens and that they have never seen something like that (especially not on an L lens...).

Did anybody here experience such problems with this lens?
What could I do about it?

Kind Regards, RK

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www.rkuster.com

I had back-focusing issues with my 70-200 which ended up with Canon twice.
I'd say send it back to the store and get another copy.

I would return it and get a new one. Depends on your consumer rights in Germany so worth checking that out in advance in case the shop tries to make you get a repair. Given how little time you have I think a new one is the best idea.

@JK, condyk: Thanks for your replies.
I'll indeed send it back to the store and try to get a new one.

I also had front-focusing on my 24-105L for the 24-35mm range. Sent it to Canon for "calibration" and it came back much improved. If the store will not replace it there should be a factory service center in Germany where it can be sent.
Best of luck.