EOS R7 AF Not Working Properly with 100-500mm Lens

[Tommyboyks]

I have a Canon R7 camera and recently purchased a Canon 100x500mm lens. The auto focus often doesn’t work correctly. If I try to focus on an object or animal and push the shutter button half-way, nothing happens. If I switch to manual an focus on the object and then switch back to auto focus, the auto focus works. What am I doing wrong?

[shadowsports]

Greetings,

This is likely a camera setting. Please see menu > AF > tab 3.

Lens Drive when AF Impossible - Turn this on [On]

If this doesn't help, we'll need specific information about the shooting mode and AF method, etc.  

[Steve01]

I have the EXACT same problem when attaching the RS 100-400MM lens to my Canon R7.  If I begin with the lens extended to 400mm about 75% of the time I only see a very blurred background with no focus point available.  I have to back the lens down to 135mm, push the shutter release half-way to focus, then extend the lens to 400mm to achieve focus.  My "Lens Drive when AF Impossible" is set to ON with "Stop focus search" set to OFF.  Tried to edit/change these two setting but in M mode this is not an option ... wondering how to change those settings?  Perhaps this will allow the lens to operate as it should.  I understand this is not a $2500 Leica lens but I've used Sigma and Panasonic Lumix telephoto lenses with other cameras and never experience this type of focus problem.  From many other comments on the various boards it sounds like it is an inherent flaw with the lens.  Any suggestion would be greatly appreciated - I don't believe I should have to constantly focus at 135mm THEN go to 400mm!

[Waddizzle]

The AF is most likely working correctly.  I suspect you have a camera settings issue.  Depending upon the shooting conditions, the camera can get confused when there is a busy background.  It may stop focusing, as described and controlled by the setting described above by Rick.

Sometimes you do want to stop the AF system and reset it, which is one of the reasons why I program the {AF-ON] button for [AF-OFF].  It takes more time to read about it than it does to do it.

The AF system may or may not reset itself once the metering timer expires, which is a behavior that depends on yet another camera setting, of course.  I’d rather just give the button a quick tap, and I can reacquire my subject without having to wait for metering to expire.

[shadowsports]

Greetings steve01,

I'd just like to add there is nothing inherently wrong with the RF 100-400.  It does not require that you decrease the FL to achieve focus.  It will focus at any FL 100-400 as long as your subject is not closer than the MFD.  Try using the AF-on button as Waddizzle suggests and see if this doesn't help.  😃