Quote Originally Posted by Alan


wickerprints, that's an interesting point you've made.


I've used my 70-200 f/2.8 at 70 mm, 200 mm, everything in between, from f/2.8 up to f/11. These are my anticipated shooting conditions, and I would think anyone using this lens would never be limited by one f stop or distance, etc.


So, I'm just curious what is the big deal for anyone to find precise focus for such a lens.
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Of course, the versatility of zooms is one of the reasons why many photographers like to use them. Remember those multiple choice tests, where the instructions say "choose the BEST answer?" That's the situation we find ourselves in when using microadjustment. You just have to pick the one best solution, presently.


Also, bear in mind that some lens+body combinations are just off, period, and sometimes consistently so across all shooting parameters. Adjustment can rectify this situation. Sending the lens to Canon for recalibration may also help but it may not, because you don't know if it is your camera body that is contributing to the issue.


Why is it important? Arguably for wide-angle zooms, critical focus isn't necessary because you have enough DOF. But for something like an 85/1.2L II or a 300/2.8L IS, microfocus adjustment can make the difference between getting a high hit rate versus a bunch of out of focus shots wide open. Some people shoot narrow DOF in fast-paced conditions and precise AF is always appreciated.


Not all of my lenses have been adjusted. The only one I did adjust was my 70-200/2.8L IS (+10), because it was consistently off. My other ones were mostly fine, except the 24-105/4L IS which was backfocusing on one end and frontfocusing on the other (though I can't remember which was which). So I compromised and left it at 0. In most real-world shooting conditions I would be hard pressed to notice this behavior, but it does make a tiny difference in how sharp I can get a photo.