7D Back button focus?

Started Dec 27, 2012 | Questions thread
paparios
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Re: 7D Back button focus?
In reply to WilbaW, Jan 2, 2013

WilbaW wrote:

Matt wrote:

one day the AF didnt work anymore. The lens was handled "normally" before. Canon repaired the AF system, whatever that means. Canon diagnosed and repaired it.

There is a flat rate repair fee of $100 for this lens as it has a design flaw and breaks randomly

Okay, so from what you've said, it just didn't work one day, not while the focus ring was being turned in AF mode or because that had been done to it a lot, but for an unknown reason, not identified by you or Canon as a mechanical failure in the gear-train. But since "everyone knows" that touching the focus ring in AF mode will break your lens (it says so on the Internet, right?), then that must be the reason. (A quick search suggests that 50/1.4 is susceptible to impact on the front of the lens, so there are other plausible explanations.)

So I repeat my request - can anyone point me to a credible, well-documented case of a lens being harmed by turning the focus ring in AF mode?

I can only testify about the lenses I have. With the EF-85 f1.8, EF-100L, EF70-200L there is no problem, as they all can be refocused manually while in AF. With the EF-50 f1.8 and the Tamron 28-75 f2.8, you feel you can't do it, as you feel the resistance of the lens to manually move, suggesting it is better not to force it.

Miguel

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