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New Contributor
Posts: 3
Registered: ‎08-19-2017

24-70 2.8 Lens focus ring queston

[ Edited ]

I just purchased a canon 24-70  2.8 L lens  on Ebay and noticed that the focus ring has no stops ? in other worrds once it reaces min or max focus it keeps turning. Is this normal? Want to make sure It is good

Thanks you first L Lens

should not that is with it not attaced to the camera and in manual or Af mode

Honored Contributor
Posts: 7,910
Registered: ‎12-07-2012

Re: 24-70 2.8 Lens focus ring queston

The focus ring itself will not stop but the figures in the feet/meter window will stop at their extreme ends.  I believe they are .38 meters and infinity.

A lot of Canon stuff. Along with, a lot of other stuff.
New Contributor
Posts: 3
Registered: ‎08-19-2017

Re: 24-70 2.8 Lens focus ring queston

I just found a Youtube video that shows that it does.
Thanks anyway
New Contributor
Posts: 3
Registered: ‎08-19-2017

Re: 24-70 2.8 Lens focus ring queston

Sorry did not see your reply, Thank for the quick responce
Esteemed Contributor
Posts: 2,993
Registered: ‎06-11-2013

Re: 24-70 2.8 Lens focus ring queston

The focus ring on Canon "L" series lenses with USM focusing motors are deliberately designed to slip (like a clutch that is only partially engaged).  This allows you to do full-time manual focus even when the lens is in auto-focus mode.  You don't have to worry about breaking anything because there's no hard mechanical engagement between the focus "ring" and the actual focus mechanism inside the lens.

 

The lens barrel has a window which reads the current focus distance.  Watch inside that window as the lens reachs the limit of focus in either close or far directions, you might notice you can very very gently feel the focus stop... but it will be possible to continue to rotate the ring on the the lens barrel.  

 

Another variation are the Canon "STM" lenses.  They don't even have a clutch... they are 100% electronic interface.  The computer notices you moving the ring and responds by adjusting the focus inside the lens (but they require power or they don't work at all).

 

The basic non-STM and non-USM lenses do have a mechanical interface and you should not attempt to manual focus them when the camera is trying to control focus (doing so can damage the lens).  But this restriction doesn't apply to USM lenses (such as your "L" series lens) or to the STM lenses.

 

 

Tim Campbell
5D III, 5D IV, 60Da
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