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EOS RP front focus with EF lenses - Please CANON add MFA to RP!

Started Dec 23, 2019 | Discussions thread
Peak freak Contributing Member • Posts: 938
Re: EOS RP front focus with EF lenses - Please CANON add MFA to RP!

I've been thinking! (I've been warned about that, but I still do it...)

My (recent) understanding was that the sensor acquires focus and drives the lens to the required position. This may allow for lens errors to show up.

However, the sensor 'sees' through the lens. It knows focus only when the lens gives optimum contrast or objects are in phase. In other words, the sensor (or camera) doesn't tell the lens were to focus. It just knows when things are in focus because it sees that they are. If the lens isn't focused properly then the sensor won't get correct contrast or phase - it should keep moving the lens focus elements until things line up.

So, mirrorless on sensor focus should be infallible. What am I missing? Are tolerances (probably for speed) loose for older lenses? Why though could the RF70-200 front focus?

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