Problem with the Canon 28-135 IS USM

[PictureGuy_StJoe]

I have been having problems with the auto focus on my lens. The focus doesn't seem to hold. It hunts forever before it locks on. When it finally does, it doesn't always hold. I'll wait for the focus, and then it'll get it, and then when I take the picture it will lose it and I get a blurry shot. I figured it was operator error at first, but it happens on the tripod with the cable release, too. Manual focus doesn't have the same problem. Which is fine for me, but I am not the only one who has to use the camera.

Has anyone else experienced this? Or even understand what I am talking about?

 

[Big Mike]

What focus modes are you using? It sounds like you are using servo when what you want is one shot mode.

 

[PictureGuy_StJoe]

No it isn't set for on Servo. It is AI Focus. Of course, just like taking the car to the shop, though, I can't re-create the problem when I want to actually study it. I'll do a little more work with it.

 

[Big Mike]

No it isn't set for on Servo. It is AI Focus.

But that still isn't single shot.

What I've done on my cameras, is to change CF#4 so that AF is not turned on by the shutter release button. AF is controlled with the * button on the back of the camera. This way, I can turn on & off the AF with my thumb as needed.

 

[PictureGuy_StJoe]

It's amazing what you can find out. I had no idea you could do that.
I will try this technique for a while and see if that helps. Just because I have been doing this for going on 4 years, doesn't mean I know everything about this camera. I learned something.