24-105mm f/4.0 L infinity focus troubles

[dschwen]

Hello forum members,

I have a 24-105mm f/4.0 L that has been giving me headaches for some time now.
It simply won't produce sharp images at 24mm for any object further than 200ft away.
I've had it sent to Canon twice already. Once they did nothing and once they "adjusted" my camera's autofocus settings.

It is not the autofocus. I've tried focussing manually to no avail. I dont care about the distance reading in the window on the lens barrel. I don't care if the lens is parfocal or not. At 24mm it does not focus on anything beyond 200ft away .

I made manually focussed image series slowly changing the focus distance and it looks like I just cannot turn the focus ring far enough towards infinity. The pictures get gradually sharper, but before I hit a good focus the ring hits the mechanical limit.
I've gotten rather frustrated about this to the point where I'm about to open the lens up myself (probably a terrible idea). Does anyone have any suggestions? I'm based in Northern New Mexico. Does anyon know a knowledgable repair shop the can recommend?

Thanks,
Daniel

[Carnac]

The lens needs to go back to Canon. This should not be happening with any lens. I don't suggest opening the lens - they take special tools and precision alignment equipment.

I've had good luck with the Canon repair facility in Irvine, CA. Send a complete description and some pictures if possible. Tell them you have had Canon look at it twice with no success.

I assume that other lenses work OK on your body? If any question, you may need to send the lens and body for repair.

Good luck, the 24-105L is an excellent lens.

Jim

[7D5D]

Do not repair it yourself. I'm assuming the two trips it made to Canon already were to the Irvine facility. I would be very ticked as well. Call Canon and arrange for a 3rd repair and tell them to get right this time or to send you a new replacement. Make sure they know this lens is coming in for the 3rd time. You might even want to ask for a loaner. Send in some sample images with documentation. I've had good luck myself with Canon service but I've read of several other people where it took multiple trips to things right. Good luck, please keep us posted.

[dschwen]

Ok, I'll send it to irvine. The previous trips were to the Newport News center (I lived in the midwest then).

The only thing that bugs me is that it is hard to show something that is not there (i.e. focus at infinity). I can add a few blurry pictures, but at the end of the day it does not prove anything. I could just be too dumb to focus my pictures. I always get the sam tireing responses:

* your autofocus is locking onto something close

 NO I USED MANUAL FOCUS!!!!

* the image stabilizer might be broken

 NO, I TURNED IT OFF

* it may be your camera body

 NO, I TRIED IT ON MULTIPLE BODIES

* when you say focus to infinity you are probably truning the barrel all the way to the left, most lenses focus to infinity slightly before they hit the mechanical stop (this helps the AF)

 NO, I'M NOT A MORON. I DON'T CARE WHAT THE LENS BARREL READS. NOWHERE IS THE IMAGE EVER FOCUSSES TO INFINITY!

* yeah, but the lens is not parfocal

 WHAT DOES THAT HAVE TO DO ITH ANYTHING!!?? AAAHHHRRGGGHH!!!!!! 

* The 24-105 is not sharp anyways, you shuld not expect the omage quality of a fixed focal length lens.

 IT FOCUSSED PERFECTLY FOR THE FIRST 4 YEARS I OWNED IT. I KNOW THE DIFFERENCE BETWEEN NOT TACK-SHARP AND COMPLETELY UT OF FOCUS

I've heard them all!

[Carnac]

Guess you didn't really need to post here if you have heard them all.

Don't know what you were expeciting. Sounds like the lens was working and now it doesn't - so the lens is broken - options are: send it to Canon again, send it to another lens repair shop, buy a new lens, take the lens apart yourself (after which you will probably need to buy a new lens).

[dschwen]

Haha, touché! 

I guess what I wanted to hear is any of the following:

* The issue is called xxxxxxxx

* The reason for the issue is most likely a wrongly adjusted xxxxxx

* I've had the same problem, canon fixed it for me

* When you send the lens to them make sure to tell them xxxxx