Canon 500 f4 auto focus problem !

Hello ,

I have recently bought a new canon 500 f4 L IS II lens . During the field test I found out that in order to achieve auto focus, I always have to rotate the manual focus ring and thn only autofocus starts . Sometimes while auto focus is achieved in mid way it loses focus while I try to focus on different area , again I have to rotate the manual focus ring and then autofocus starts. Is there a way to reset the lens ? Or is there any other switch or button that is playing havoc ?

Regards,
Haseeb.

Just a thought here, but make sure the "Focus Preset" switch is set to OFF.

Thank you Daniel . Initially it was on but had turned it off on the field when I saw the problem I turned it off but the problem still persists

make sure the focus search option in your camera body is set to ON

I'll hazard a guess, Haseeb (unless you want to ship me your gear :))

It's likely your camera setting.

The canon bodies I have offer a setting
C.Fn III: Autofocus/Drive Lens drive when AF impossible
0: Focus search on
1: Focus search off

If you set it to off, and you're badly out of focus, the camera won't drive the lens. Which could be why once you manually focused to bring the lens in the ballpark, the AF started working again.

Good luck

Thank you Arash and Sidharth, but that option was also turned on !

OK, now check your distance limiter switch. If it is set to 10m or more, and your subject is within that you will not be able to autofocus on it, but you can still manually focus...but if you then focus on something farther again the AF kicks in...come back to that near object you won't be able to focus except manually...

edit to add: same goes if set in the middle setting, which is to AF only between 3.7m to 10m, and not anything beyond that (except manually).

Tried it Daniel as suggested by you, still not happening

Does the problem occur with other lenses or if you add an extender? Which camera body are you using? Try cleaning the contacts on both camera body and lens. Also make sure the AF/MF switch is set to AF.

Hello Jim -- I used it without TC or extender , and the bodies on which I tried it are 7D , 5D MK III and 1D MK IV , the 300 2.8 IS II and 70-200 mm works perfectly well with the abv bodies but not the 500 f4 so far . And yes the switch is set at AF .

I am afraid you need to send the lens to Canon for evaluation

I agree with Arash...I can't think of anything else that could be causing this....

This is a total shot in the dark but....by any chance do you have any type of
cover over or touching the ring?

The reason I brought it up was, I have a self made lens cover on my 600.
There were times the focus wasn't working and I had to manually turn it
a bit to get it going again. Turns out the cover I made was interfering with
the ring.

Doug

Hello Doug -- That is very interesting , but i had no cover or lens coat in place . I had returned the lens to Canon and they are going to replace it . Will update once the new piece reaches to me .

Thank you every one for your help .

Thank you everyone for your suggestion and ideas .

i sent the lens to Canon service centre and they diagnosed a firmware problem with the lens . The lens is working absolutely fine now , just have to get used to it now to get sharp results while shooting wide open.

Thanks,
Haseeb.

Thanks for the update Hasseb. I am glad all is well with your lens now!