Can only focus when zoomed in

Paulbeckett · May 31, 2012

Hi we have borrowed a hi end lens for a school project, but we can only focus the lens when the camera is fully zoomed in
We have tried lots of different settings on the camera but still can't get it to focus

Any suggestions

Michael Rogers · May 31, 2012

Lots of zoom lenses focus differently at different focal lengths. But if it's not focusing at all at other focal lengths... the focusing barrel might be off?

Paulbeckett · May 31, 2012

Info

A bit more information
When I select manual zoom I still can't focus it
The lens is a canon hj11

Michael Rogers · May 31, 2012

So it will focus fine in servo zoom? where did you rent it from?

Paulbeckett · May 31, 2012

No

No it won't focus in servo, only when zoomed in fully

Michael Rogers · May 31, 2012

Who loaned it to you? Are they reliable? Have you tried different lenses? Do they focus?

If other lenses work, it's something wrong with the lens.. if you haven't tried other lenses you should

David.rhsc · Jun 1, 2012

Clarify please:

Is that you zoom in, set focus, zoom out and focus changes.

Or is it that you can only find focus at the long end of the lens, and all other focal lengths are not sharp?

jax_rox · Jun 1, 2012

Also - how close to the lens are the things you want to focus on?

PaulGriffith · Jun 1, 2012

You have to set back focus. It's probably the last ring on the back of the lens (closest to the camera) and will probably have to unscrew a little knob to be able to adjust it.

Tp set back focus:
Zoom in all the way, focus, then zoom out all the way and adjust the back focus ring until it's now in focus. If done right, everything should now be in focus throughout the zoom.