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Canon 100-400 EF 4.5/5.6 not focusing (auto or manual)

SethHarrison
Apprentice

I had to tighten a screw on the lens mount of my 100-400 lens because it was loose and not coupling completely with the camera. After tightening it (and now getting a good fit with the camera), the lens is not focusing, either in autofocus or manual focus) In autofocus, I can hear the motor working when I depress the shutter halfway, but it doesn't focus, and as I said, it also does not focus in manual focus mode. This is happening on two different 1Dx bodies, so I know it's not the camera. Any ideas?

8 REPLIES 8

Tronhard
Elite

My first thought is to slightly back off the tight fit you got and see if that makes a difference.


cheers, TREVOR

Before you ask us, have you looked in the manual or on the Canon Support Site?
"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
"

I was thinking the same thing. I'll try that. Thanks!

ebiggs1
Legend

"I had to tighten a screw on the lens mount of my 100-400 lens because it was loose and not coupling completely with the camera."

 

I think unrelated and just coincidence. It needs service. Call Canon 1 (800) 652-2666

EB
EOS 1DX and 1D Mk IV and several lenses!

You may be right Ernie, but getting the OP to simply take some of the pressure off the lens screw might be a resolution that will be a lot cheaper and more convenient that sending it in for Canon to do the same and charge for it.  If that doesn't work, then absolutely invest in a service.


cheers, TREVOR

Before you ask us, have you looked in the manual or on the Canon Support Site?
"All the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
"

Hi guys. 

If that works Trevor it would still recommend the OP send it in for service. The lens mount is a rigid piece. It is held in by four screws. If everything is to factory spec completely removing one screw shouldn’t make a difference (I just tried this on an old lens that I have on my display shelf). 

John Hoffman
Conway, NH

1D X Mark III, Many lenses, Pixma PRO-100, Pixma TR8620a, LR Classic

jrhoffman75
Legend

@SethHarrison wrote:

I had to tighten a screw on the lens mount of my 100-400 lens because it was loose and not coupling completely with the camera. After tightening it (and now getting a good fit with the camera), the lens is not focusing, either in autofocus or manual focus) In autofocus, I can hear the motor working when I depress the shutter halfway, but it doesn't focus, and as I said, it also does not focus in manual focus mode. This is happening on two different 1Dx bodies, so I know it's not the camera. Any ideas?


When you say “not coupling” do you mean the loose screw prevented full rotation of the lens so it wouldn’t click into position?

John Hoffman
Conway, NH

1D X Mark III, Many lenses, Pixma PRO-100, Pixma TR8620a, LR Classic

ebiggs1
Legend

"If everything is to factory spec completely removing one screw shouldn’t make a difference..."

 

Of course but if it makes him feel like he did something go for it. Than send it to Canon!

EB
EOS 1DX and 1D Mk IV and several lenses!

SethHarrison
Apprentice

Thanks all, CPS has the lens and is taking a look at it.

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