Canon EOS20D

[DianaS]

I have my Canon Zoom Lens, EF 70-200mm !.2.8 L IS USM on the camera and when I try to take a picture the camera tries to focus and seems to pulse between focusing and unfocusing.  Haven't had that problem before.  Does anyone know how to fix this?

[ScottyP]

1. Check the focus limiter switch on the lens. If it gets bumped without you knowing it prevents the camera from focusing on close things, which can be confusing.  

[DianaS]

Do you mean the AF, auto focus, vs MF, manual focus?  I did check those and both are on AF

[ScottyP · Accepted solution]

Hi. 

No there should be a switch with 2 or 3 settings that are something like distance ranges. 2.5 M to infinity, etc. I don't have the camera here and I'm at work.  It limits the distances at which the camera will focus. One of the settings keeps it from focusing at close things so if you are shooting planes at an air show but people are walking in front of you, the camera doesn't totally lose focus on the far away planes and try to drill down on some spectator's head every time one passes through the frame. 

A couple of times that switch has been set that way and I forget that the next time I use the lens, and the lens seems to be having a focus malfunction.