Canon EF-S 55~250mm, IS, STM Lens. The problem is: When setting up a shot, I will press the shutter release button half-way which activates the Auto-Focus System. The image will be in focus, however when I decide to change composition and then set up again, the lens will not bring the image into focus and the In-Focus confirmation light at the bottom right hand corner is a steady beam indicating that all is good to go. I have tried moving back a bit, thinking I may have gotten a little too close, however this maneuver did not work. I continued to attempt to get the image into focus and finally after four attempts, the lens brought the image into focus. This has happened a couple of times before, but since it seemed to correct itself, I let it go. This time, it took an inordinate amount of attempts before the image was brought into focus. Battery was still at 100% and revealed three red bars indicating recharge performance. The only change I made was to composition, so no camera, lens changes were made. I wonder how the In-focus confirmation light came on when it was very obvious that the image was way out of focus. Cheers, Tony Any helpful hints/suggestions will be greatly appreciated.
I have similar issues with my 60D ant my two favorite lenses, 24-105 and Tamron 28 - 200mm lens. I ususally put the lens in manual and focus that way, failling this, with the lens in manual turn turn focus dial so it is well out of focus and then switch the auto switch back into auto focus and then refocus, with such a large adjustment the lens usually refocuses. Hope this helps, Caladina or Johnsey is our next best bet as they use newer gear similar to what you use, all the best with it, Tony.
Tecnically it shouldn't do this unless the subject distance is the same but it can happen, the easiest way to force a refocus without resorting to manual focus is to point the camera down to the ground and refocus so that you get a large focus shift then refocus again on your subject.
Okay, many thanks for your assistance. To add more fuel to the mix, I have an identical, spare lens. Took it out yesterday with it installed on my Canon EOS 7D MK II body and the same problem reared its ugly head. So, I believe that Craig is correct when he indicated that it may be (like me) an aging process problem. They were in like new condition when I purchased them from my best friend in Summer of 2014 and both have had a lot of use. Is this a sign that they are both at the end of their life span? Again, many thanks. Tony
