17-55 efs focus help

I am having trouble with my focus on my 17-55. It will not repeat focus at the same spot every time when I test it on a tripod using center point AF one shot. When I take say 8 shots maybe 1 or 2 will have correct focus. I tried doing a micro adjustment but the problem continues. I focused on the Energizer battery in the center for 8 shots. The batteries are 3 feet away from the sensor plane and are placed in a line at 45deg to the camera. Its like it floats all over. One time 6 of the 8 are ok than the next maybe 2 of the 8 are good. I set the focus ring to infinity and let it find focus for every shot. All shots were done with a 7d Mark ii which was just serviced by Canon within the last 2 months. Camera settings were F2.8 iso 800 one shot center point AF. Any thoughts as to what may be going on?

My first thought: Is IS on? My second thought: How stable is the tripod? Third: How are you actuating focus/shooting? With button on the camera or on a remote? Any sort of delay on the shot?

IS is off 10 second delay using back button with mirror locked up and tripod is rock solid

one more shot from the same series.

jlstan wrote in post #17914607
IS is off 10 second delay using back button with mirror locked up and tripod is rock solid

Was about to ask about MLU. Might want to try the test with a remote. You haven't given any info on the tripod used. How solid the floor is, how drafty the room is, whether someone is bouncing on the couch 10 feet from the tripod, etc Eliminate the tripod before blaming the lens.

I'd try it with a bit more space between batteries and a better background to get a harder contrast edge.

Also, I assume that you have tried another lens and it focuses solidly thus narrowing down the problem to the lens itself and not the body.

Another thought, as well: How high is the center column on the tripod extended?

also shot with my 100mmL focus is spot on

gjl711 wrote in post #17914613
I'd try it with a bit more space between batteries and a better background to get a harder contrast edge.

Also, I assume that you have tried another lens and it focuses solidly thus narrowing down the problem to the lens itself and not the body.

jlstan wrote in post #17914618
also shot with my 100mmL focus is spot on

Excellent point. Did you use the same technique with the 100mm? i.e. - 10 sec delay, back button?

Sounds like an issue with the lens then. Time to send it off to Canon.

Shooting with a Manfrotto 055XPROB with center column all the way down. everything from the tripod to the floor is rock solid. No one else in the room. I will try a different setting next however I have been noticing this problem for quite some time now with this lens. I would try a few shots with the 17-55 doing a portrait shot and would get soft eyes every few shots. I than would switch to my 100mm L and get sharp shots every time

Mirror slap or a slight tripod wobble isn't going to cause a focus error that great. One other though, I am assuming that you are defocusing the lens the same way between shots.

same technique with 100L

setting focus to infinity between shots

sux cause I hand hold my 150-600 sigma all the time and get better focus than this 17-55 is giving me