Canon 100-400 Focus Problem

NoslocG

Just recently purchased a 100-400 L USED (now im kicking myself) and I am having problems with the Auto Focus. Sometimes it works just fine... and then all of a sudden it wont focus. I can hear the IS kick in and the focus point blinks in the view finder, but the AF is clearly not working. The shutter will not activate unless switched to manual focus. Swich the camera on and off a few times and it will occasionally work momentarily. SUPER FRUSTRATING!!!!


Im wondering if anyone has had this problem? Have you got it fixed? Any suggestions? I am traveling to Costa Rica on the 29th and am praying to have working gear. How long do canon repairs usually take?

Thanks thanks thanks!!

kdog

Make sure you have the focus limiter switch set correctly. You will get a symptom like you're describing if you have the focus limiter switch set long, and you're trying to focus on a near object. It will never focus that way. If the switch is set to short, and you're focusing on a distant object, it may hunt a while before it finds the focus. I'd try a mix of near and distant objects to see if you can see a pattern.

If that doesn't work, I'd try cleaning the electrical contacts on the lens. Maybe they're not getting a good connection. If you still have no luck,try to return it to the seller, and buy a new replacement.

Canon service usually runs 10 days or so, so you're right against the wire, especially with the holiday. I'd get the lens to them pronto if you're going to go that route, and see if they can expedite it for you. Pay for overnight shipping both ways, or hand deliver it if you're near the Irvine, CA or Jamestown, NJ service centers.

Good luck and let us know what happens.
-joel

NoslocG

kdog wrote:

Make sure you have the focus limiter switch set correctly. You will get a symptom like you're describing if you have the focus limiter switch set long, and you're trying to focus on a near object. It will never focus that way. If the switch is set to short, and you're focusing on a distant object, it may hunt a while before it finds the focus. I'd try a mix of near and distant objects to see if you can see a pattern.

If that doesn't work, I'd try cleaning the electrical contacts on the lens. Maybe they're not getting a good connection. If you still have no luck,try to return it to the seller, and buy a new replacement.

Canon service usually runs 10 days or so, so you're right against the wire, especially with the holiday. I'd get the lens to them pronto if you're going to go that route, and see if they can expedite it for you. Pay for overnight shipping both ways, or hand deliver it if you're near the Irvine, CA or Jamestown, NJ service centers.

Good luck and let us know what happens.
-joel

Hey Joel,

WOW... you just saved me a HUGE headache!!! It was the focus limiter. Now it works fine. Can you tell I'm new to these bigger lenses?? Apparently my SF apartment is too small for me to focus on anything far enough away.

I even went down to Calumet and asked for a guy to look at it. He listened for about two seconds and said the only thing they could do is send it to Irvine for $35. Glad I said no thanks!

THANK YOU THANK YOU THANK YOU!!!!,
Colson

kdog

Yay! I love a happy ending.

Onward to Costa Rica, and beyond!