EF 70-200 2.8 IS USM: does not focus

[NancyEv]

Recently, I am unable to focus my lens using the focus ring (stuck on infinity-when I turn the ring, nothing happens (R7 camera).  When I try to use center point focus, the camera cannot focus on things closer than infinity.  Sometimes Eye-detect works, but most of the time it doesn’t.  Also, when I shoot in eye-detect mode, the first picture is sometimes good, but subsequent images lose focus.  Thoughts?

[Tronhard]

Hi Nancy and welcome to the forum:
Sorry to learn you are having issues. To try to eliminate possibilities, let's explore some variables. 
What brand of adapter are you using to connect your lens to your R7, please?
Are you able to test the lens on a DSLR body?

[NancyEv]

A canon adapter.  I no longer have a DSLR.  This behavior of the focus ring not moving off infinity occurs when the lens is off the camera.  I’ve used this lens successfully for many years; I don’t think this is operator error  :).  I can’t find anything about this in the manual, and have searched around the support site, but can look some more.

[Tronhard]

Hi again:
Thanks for your prompt response.  No suggestion of operator error from me.  However, I still need to isolate the cause.
Just to clarify: I'm not sure what you mean by "This behavior of the focus ring not moving off infinity occurs when the lens is off the camera."  I am trying to reconcile this with your other statement "When I try to use center point focus, the camera cannot focus on things closer than infinity"
Did the lens ever work at all when using the EF-RF adapter?

[NancyEv]

Okay, I’ve done some more testing.  
—When I put the lens on the camera (R7 with a canon adapter), I can focus, and the little window showing the distance on the lens changes to something approaching the real distance.  This didn’t seem to happen all the time in the field last week.

—When I put the lens in MF mode, the little window says infinity no matter how much I turn the focus ring, and I can’t manually focus on anything, close or far.

—Interestingly enough, when I push the shutter button, the view through the viewfinder seems to jump to in focus only while I have the shutter depressed, even when the lens is in MF mode.  I have dissociated focus from my shutter button so this was a surprise.  I double checked my settings and I do not have any focus on my shutter button.

—I’ve been going through my photos from a recent trip and have a surprising number where the first photo in a series is sharp, and subsequent ones go out of focus slightly (subject did not move), which is not my experience with my 500mm lens.  

[deebatman316]

Have you tried turning the focus ring both ways to see if it moves away from infinity. This lens supports what Canon calls Full-time Manual Focus. The focus ring can be turned with the lens set to AF. Without any type of damage because there is a clutch underneath the focus ring. If it does move from infinity there's nothing wrong with the lens. Also which EF 70-200mm F/2.8L IS lens do you have. Canon has released 3 different versions over the years.

[NancyEv]

Hi--It is a EF 70-200mm f/2.8L IS USM according to the label on the lens (but according to Canon, the serial number belongs to a IS II USM...go figure).  When I turn the focus ring in either direction, the focus window doesn't change whether the lens is on or off the camera.  BUT--today when I was testing to confirm, the focus window switched to ~5m and then back to infinity (right after I put it on the camera).  

[deebatman316]

Do you hear the AF motor running all the time.

[NancyEv]

Yes, whether in MF or AF, and with or without IS on.

[deebatman316]

Remove the lens from the camera then turn the focus ring. The AF motor should not be active when the camera is off.