Focus problems with my 2.8L 24-70

TheCheesehead

Hi,
My 2.8L 24-70 mounted to a Canon XSI seems to have focus issues intermitantly. I will place a focal point on the subject, and the red dot just blinks and wont focus. This will be even in daylight conditions. Also, I'm not too close. My 2.8 70-200 IS focuses just fine. This lens is only a few months old. Should I send it back in to Canon? (I bought it from B and H, but I have to send to Canon for repairs right?)

Hey, thanks again!!

ziggy53

If you can lay your hands on another camera body, test the lens on the second body first.

What are the conditions under which you are experiencing the focus problem and what subject matter?

What happens if you switch to manual focus? Do you get consistent focus confirmation in manual focus?

Scott_Quier

In addition to what Ziggy has already mentioned, another thought occurs .... Is the focus point on a medium to high contrast object or is it all "the same"? The AF on the camera needs something with some contrast in order to function properly - the more contrast the better.

TheCheesehead

Thanks for the replies. It happened again tonight shooting a tball game, 6pm, plenty of light, plenty of contrast...sometimes it focuses, sometimes nothing, the focusing indicator flashes. No problems at all when I switch over to the 70-200, or even the 18-55. Is that what you are referring to Ziggy...go to manual and that light will be solid when it's focused? I didn't realize there was an indicator when it focuses, just thought you had to go by eye.

ziggy53

TheCheesehead wrote: »

... Is that what you are referring to Ziggy...go to manual and that light will be solid when it's focused? I didn't realize there was an indicator when it focuses, just thought you had to go by eye.

Correct, when you set an AF lens to manual and use the focus ring the camera will "confirm" with a "beep" (if the sound is enabled) and a green dot.

If that works normally, I'm not sure what's going on, especially when the 70-200mm is working correctly. It does sound like a lens issue.

ziggy53

TheCheesehead wrote: »

... This lens is only a few months old. Should I send it back in to Canon? (I bought it from B and H, but I have to send to Canon for repairs right?)

Check with B&H first. If you are over 15 days then you will probably have to send the lens in to Canon. I believe that the exception is "imported" items which are warranted by B&H.

Phone: 800.221.5743 or 212.239.7765

TheCheesehead

Focus problems with my 2.8L 24-70
Ok, found the green light, it does operate in manual, but so did the autofocus....it's intermittent. This morning it was working great...could it be a contact problem? I cleaned them before but it still acted up.

ziggy53

TheCheesehead wrote: »

...could it be a contact problem? I cleaned them before but it still acted up.

It is possible for the contacts to be part of the problem. Also check to see if the lens has some rotational "play" in the mount and see if the lens works better with the rotation slightly to one side or the other.

Is this a problem that just recently started?

TheCheesehead

Focus problems with my 2.8L 24-70
Yes, the problem just recently started. Was doing it again yesterday during the parade, it won't even try to focus, just sits there almost like it's dead, like it's in manual mode. How long is the turn around when sending it back to Canon? I need it in early August. Thanks!

ziggy53

TheCheesehead wrote: »

... How long is the turn around when sending it back to Canon? I need it in early August. Thanks!

I suspect that you are OK if you send it in now. Canon should send you an estimate before repairs, but I think you can also authorize an amount that allows repairs without further approval. Contact Canon and see if that can be arranged.

In the mean time, if it looks like its taking longer then just rent for anything important or pick up a backup lens.

Do set up for the repair ASAP:

http://www.usa.canon.com/consumer/controller?act=OnlineTrackSearchAct

TheCheesehead

Thanks!! Just a follow-up, called Canon Monday morning, they said to send in for warranty work, sent it in Monday morning, recieved in NJ yesterday...and that's where I'm at now. Hope to get it back in two weeks for trip to Mackinac Island.

heatherfeather

I have sometimes experienced something similar. What was happening? The grip had gotten bumped to the off position, which makes the AF get all screwed up. Flip it to on and it was fine. Are you shooting gripped?

TheCheesehead

Focus problems with my 2.8L 24-70
Hi, yes I am shooting gripped, but the grip was on at all times. I shoot portrait oriented a lot and notice quickly when the switch is off. It will be interesting what Canon finds. I have a work order number, so I know they are working on it.

TheCheesehead

Focus problems with my 2.8L 24-70
Just checked repair status online, and it says it is repaired, but not shipped yet. Doesn't say what they did or what the problem was.

Seefutlung

Good luck ... alls well that ends well (fingers crossed).

Gary

TheCheesehead

Focus problems with my 2.8L 24-70
Just got it back, wow that was fast, I sent it out FedEx 7 days ago! They overnighted it back to me. Here's what the note from Canon said, "your autofocus part was out of position causing the AF to operate improperly. The USM focus assembly was replaced and product functions were confirmed. Checked all, adjusted center/tilt/front, back focus and cleaned to factory specs."

Sweet! That may have been why my focus didn't seem very sharp on subjects further than 20 feet away (I posted that on an earlier thread, before the AF acted up completely as described in this thread). I checked it out myself now and it's working great! Thanks Canon! Thanks to those of you in this thread that helped out too!