Can Canon EOS DSLRs use phase-detect autofocus in Live View?
Asked 8/22/2012
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On Canon EOS DSLR bodies with Live View, is it possible to autofocus using the camera’s normal phase-detect AF points instead of contrast-detect AF? If so, which models support this and how does it work?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
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In Live View, the mirror is up and the AF collimators do not have view of the scene and can't do any focusing. The EOS Quick Mode flips the mirror down, exposing the scene to the collimators and then flips the mirror back up. There isn't a way for a traditional mirror-equipped DSLR to show live view WHILE using the collimators to focus.
The Sony Alpha DSLRs DO do this, because they don't use a traditional mirror - they use a semi-transparent mirror. This splits incoming light to the collimators and the sensor simultaneously. This is why the newer Sony Alphas can shoot a high FPS while continuously auto-focusing, and why they use an Electronic View Finder. The EVF is used because the light entering an Optical View Finder would ruin the exposure/metering of the scene with the semi-transparent mirror setup and always (except when the shutters are active during exposure) exposed sensor.
Originally by user11295. Source · Licensed CC BY-SA 4.0
user11295
14y ago
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Generated from our catalog & community — verify before relying on it.
Yes—many Canon EOS DSLRs with Live View offer a phase-detect option usually called Quick Mode. In this mode, the camera temporarily drops the mirror, uses the normal DSLR AF points to focus, then raises the mirror again and returns to Live View.
Important limitation: a traditional DSLR cannot continuously display Live View while using its normal phase-detect AF sensors, because those sensors are blocked when the mirror is raised. So Quick Mode is not simultaneous Live View + phase-detect AF; it briefly interrupts Live View to focus.
Canon also offers a Live Mode that uses contrast-detect AF directly from the imaging sensor.
From the answers provided, this feature is available on models such as the EOS 60D and 7D, and similarly on some Rebel/Ti models. In short: yes, Canon DSLRs can use phase-detect AF during Live View, but only by momentarily leaving Live View to do it.
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