Need help with unusual 100-400 symptoms

I just yesterday got a used 100-400 on EBay that looks like pristine condition, even never used. Not a mark on it, glass perfectly clear, looks like never even tripod mounted.

I photograph Little League baseball tournaments and really gave the lens a workout today. I had some unusual situations. Several times AF would continuously hunt and never focus between 350-400 no matter what focus point selections I used on my 40D. Mid-day bright sun, high chainlink fence background. Other times no problem. No problem in main stadium.

After a shot at 400 then zooming quickly to 100 I felt and heard a noise that sounded like a spring or stiff wire rubbing the inside case. This never happened with simple in and out pumping, only every time after a 350-400 shot then a quick pull to 100 for a shot of a play at the plate. No other problems, good IQ.

I can return lens within 7 days. Do I have a problem??? Timely comments from 100-400 IS OWNERS appreciated.

Did you check the focus limiter switch for the AF issues? I know it sounds stupid but you'd be surprised the number of people who dont check this! or simply dont realize that the MFD when limited is quite a bit further away than youd think...

I just racked mine back really quickly, it makes a noise when pumped fast...it does kinda sound like what you describe i guess....

I have no manual with the lens and was feeling my way. Which switch is the focus limiter? I was trying to focus on the outfielder making a play. My other long glass is non IS.

pfjbaldwin wrote in post #8224836
I just yesterday got a used 100-400 on EBay that looks like pristine condition, even never used. Not a mark on it, glass perfectly clear, looks like never even tripod mounted.

I photograph Little League baseball tournaments and really gave the lens a workout today. I had some unusual situations. Several times AF would continuously hunt and never focus between 350-400 no matter what focus point selections I used on my 40D. Mid-day bright sun, high chainlink fence background. Other times no problem. No problem in main stadium.

After a shot at 400 then zooming quickly to 100 I felt and heard a noise that sounded like a spring or stiff wire rubbing the inside case. This never happened with simple in and out pumping, only every time after a 350-400 shot then a quick pull to 100 for a shot of a play at the plate. No other problems, good IQ.

I can return lens within 7 days. Do I have a problem??? Timely comments from 100-400 IS OWNERS appreciated.

your AF was probably jumping bwteen the subject and the fence. i've had this happen in bright conditions, especially when the subject was backlit.

ed rader

pfjbaldwin wrote in post #8224899
I have no manual with the lens and was feeling my way. Which switch is the focus limiter? I was trying to focus on the outfielder making a play. My other long glass is non IS.

Ok at the base of the 100-400 you have the AF/MF switch and the one that says 1.8m-inf and 6.5m-inf

6.5m-inf limits the focus path between 6.5m and infinity....which is not that much...its useful if your subject is pretty far away

Sadly im bad at baseball...position..t​hings..so i cant say..but when you said things were fine in the main stadium, which sounds a lot bigger and you were positioned further from the action, it rose the flag that said your focus limiter might be on..

My 100-400 made that noise too, was never a prob. As KenjiS has said, did you have the focus set at 6.5m to infin?

Thanks for all your feedback. I played around with the switch but am unsure if I changed settings when I was having all the problems. Will eval further when I shoot Championship games tomorrow in main stadium.

Ed Rader, this field was very bright, infield was dirt not grass like all the other fields. A lot of reflectivity off the high green chainlink background fence in this stadium. Thanks

I'm on the field between home and first base. Bases are 65 or 75 feet apart. The focus limiting could be a tough choice since I'm often closer than 20' from the players.

What are the 2 IS switch positions for?

pfjbaldwin wrote in post #8225043
I'm on the field between home and first base. Bases are 65 or 75 feet apart. The focus limiting could be a tough choice since I'm often closer than 20' from the players.

To be honest, i wouldnt limit it then, i only limit it on things like birds in flight, but birds in trees and etc i very often find im getting too close with the limiter...

IS Mode 1 and IS Mode 2, Mode 1 is for stationary, Mode 2 is for panning

I/O is on and off respectively...

thanks Ken