It's definitely possible to register an AF microadjustment for an EF zoom lens, but it's only applicable to the focal length at which the lens was tested by the user. For various reasons, an AF microadjustment that's accurate for one focal length may not be accurate for another. If this is the case for any of your EF or EF-S zoom lenses, it will be necessary to send the lens(es) in to a Canon Factory Service Center for calibration. The FSC technicians have the ability to calibrate zoom lenses at a variety of focal lengths and apply those calibrations directly to the lens.
That's very interesting, Chuck, thanks for sharing this info. It's a question I have mildly wondered about from time to time but never seen asked.
Keep in mind this is a hypothetical discussion for me personally, as I have not yet gotten a body that offers the feature. I don't know how the capability is implemented now; perhaps I'm missing something.
To me it seems that not embracing zooms is a significant missing feature in the self-adjustment process.
It would be great if a person could make an across the board adjustment that's added at every focal length, and then be able to set the microadjustment for, say, several focal lengths for the lens and have the camera do interpolation between them. It would be a two-phase process, but complex or no I'll bet people really interested in getting their focus right would rather do it than send away their hardware.
Just the first "overall offset" capability would likely reduce calibration returns markedly in that it could be used to at least center the focus around the variances within the lens.
Wouldn't this also account for variances in the body itself? In other words, one could imagine someone setting a +10 (whatever) setting for every lens. Again, a return of a body for focus calibration is avoided.
Linear Mode
