Since the EOS 70D is a digital SLR and not a camcorder, the sound recording options are different than what you might be used to. Prior to the start of recording, the EOS 70D must be set to manual sound recording before you start the video recording. This is the way to control audio whilst recording footage.
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There is a Wind Filter function you can enable in the menu.
When on safari, the wind blowing into the mike is annoying, is there away to mute that?
To deal with this, you will likely want an external microphone (the Røde "Videomic" series is very popoular... these microphones include a mounting bracket which slides into the hot-shoe -- where you'd normally attach a flash).
AND... you also probably want to put a wind muff on the microphone (these things are also commonly called a "Deadcat") -- it's the furry thing you see wrapped around microphones when using them outdoors. The Deadcat doesn't come with the microphone... it's sold as an optional accessory. Their sole purpose is to reduce the wind noise that a microphone would otherwise have if used in a windy environment.
12/05/2023: New firmware updates are available.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.