Why do lenses need AF calibration?

Started Oct 15, 2003 | Discussions thread
1ofUs! Veteran Member • Posts: 3,140
Re: Why do lenses need AF calibration?

They actually physically moved both the sensor in the body and the rear lens assembly in my lens. My conversation with the tech rep said my lens, and most lenses were actually within the specs, but that isn't good enough for the 10d, it has to be right on the center point. Cindy

Adam2 wrote:
According to a well placed Canon representative, lenses operate
within their own specifications - they have motors, acctuators,
etc. Sometimes parts wear out or go out of spec.

The process of calibration is as follows:
1) Calibrate the camera based on a target system and reference
lens. If the camera is out of specs. they adjust the parameters
via firmware to within manufacturer design tolerances (assuming
that there isn't some other major malfunction - chip misalignment,
etc. which would requre a mechanical fix).

2) Attach lenses to now calibrated camera and repeat above test.
If the system is out of spec, they adjust the individual lens.

Radu Tenenbaum wrote:

I've read lots of threads about needing to send body AND lens to
Canon for AF calibration, but I don't understand how the lens could
be out of calibration. After all, isn't the AF system a closed
loop system where the focus is adjusted until the body detects
optimum sharpness?

Also, can someone explain what is involved in performing the body's
AF calibration? Is it firmware or mechanical?

Sorry if this information has already been posted, but there are so
many posts on this topic that it's hard to do a specific enough
search to get me these specific answers.

Radu

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CindyD or SarahD
If one of us is laughing, and the other one isn't, one of us must be wrong...

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