Canon EF 28-135 IS USM 3.5-5.6 lens focusing issue

[BickMac]

I have a Canon EF 28-135 IS USM lens for my Canon 7D Mark II.  When I turn on the camera, I can usually take one or two pictures.  This is in any mode P, Tv or Av etc.  Then the auto focus is trying to lock on the object.  It's set on single point focus.  The drive motor goes full range back and forth and the green light at the bottom right of the viewfinder starts flashing and you cannot take the picture.  There are no error codes that come up.  Turning the camera off and back on plus additionally replacing or opening the battery door doesn't help.  My other 2 lenses work fine.  I can put the lens in manual and can take a picture, but the focus ring is hard to get it "just right".  Does anyone have any thoughts on what's causing or how to fix the problem?

Regards,

BickMac

[Anonymous · Accepted solution]

Do you have this problem with plenty of light or for darker scenes?

[Anonymous]

If you have a menu setting, Lens Drive when AF impossible, set it to on. It might say continue focus search instead of on.

[deebatman316]

What other lenses are you using. Those lenses may have a brighter maximum aperture. If so they will lock focus better in low light. The 28-135mm USM lens is a variable aperture lens. The more you zoom in the less light enters the camera. I used to own this lens and it's a very good one. It was Canon's first consumer grade lens to feature Ring Type USM and IS. Try using the built-in flash for AF Assist. The camera must be set to One Shot AF. For the AF Assist Beam to work. Or you could use a speedlite too.

[BickMac]

Thanks for the response.  The other lenses are Canon EF 100-400L and an EF 10-18 IS STM.  I mostly used one shot but 5 shots when whale watching (max zoom) or doing birds in flight that worked well on the other lens (100-400). Being outside doing mostly landscapes, a flash wasn't an option.