Problem with the AF of my new 18-135mm EFS IS STM lens

[seba007]

Hello,

The lens came with the EOS Rebel T5i bundle.

The auto focus is working incorrectly, focusing closer than the detected area. This is happening when I use the viewfinder. When a picture is taken using the “direct view” (LCD display) it focus correctly.

 I didn’t use the camera a lot since I bought it, now looking the first pictures I see that this problem is happening since I bought it.

I changed the zoom lens with another Canon camera and then my new Rebel T5i works fine and the same problem happens with the other camera, therefore I’m sure that the problem is in the lens and not in the camera body.

The out of focus is more noticeable when I'm taking pictures in 18mm position to an object farther than 2 meters but it is happening in any zoom position. It is clear when I compare the same picture taken with the viewfinder with one taken with the LCD Display.

I updated the body firmware and the problem continues.

Is it possible to update the lens firmaware? I couldn’t find them in the canon webpage.

I will go into an important trip next week, therefore I will not have time to send the camera to repair.

Any idea?

Thanks!

[photospark9]

Hi seba007

It sounds like the lens focus is badly calibrated from the factory (May have slipped unnoticed through quality control?). I think it is possible to fix yourself by manually adjusting the position of the front element but honestly there are probably people on here who know a lot more about it than I do.

Hope this helps.

[ebiggs1]

"Is it possible to update the lens firmaware?"

No.

It sounds like this is a trip to service if it as you stated in your post.  The AF system and terrible AF-point visibility in the viewfinder make shooting  awkward so are you perfectly sure it is the equipment and not you?

[TCampbell]

You may want to rent a lens for your trip and get this lens to service.

You'll want to be sure it really is a problem with the lens (it sounds like it is from your description).  Test the lens against a "flat" target (such as a wall).  You can hang something on the wall with high-contrast (newspaper works great) and put the camera on a tripod.  The idea is that (a) the camera is definitely not moving, (b) the focus target is definitely not moving, and (c) the target is flat and there are no distracting objects in the field of view so it's not possible for the focus system to decide to lock focus on anything OTHER than your intended target.

Next... deliberately turn the focus ring to put the camera out of focus (so that the camera HAS to move the focus).  This is mildly tricky with an STM lens since there's no mechanical link from the focus ring to the lens -- it's electronic.  The lens only accepts focus input when focus is active (e.g. half-press the shutter button, etc. to wake it up.)  I run focus all the way in and test several times, then run focus all the way out and test several times (that way it has to move focus in both directions.)

If the lens is consistently focusing closer, then it will need service.