Canon 5D Mark II HDMI signal loss when recording and workarounds for external monitoring

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2012Cameras (Film/Video/HD) forum

14 years old. Gear and prices may have changed since.

The Canon 5D Mark II switches its HDMI output from HD to SD when recording begins, causing connected monitors and converters to lose signal for a few seconds during the switchover.
The Canon 5D Mark III and Canon 7D do not exhibit this signal-switching behavior when recording.
Installing Magic Lantern custom firmware on the 5D Mark II allows setting the camera to always output SD, eliminating the signal dropout.
Some Blackmagic converter models require firmware downgrade to work reliably with the 5D Mark II's HDMI output switching, while newer Blackmagic mini-converters handle the switchover better than larger models like the Hyperdeck Shuttle.
The 5D Mark II provides composite video output through a 3.5mm mini-jack port that does not cut out during recording, offering an SD-only alternative to HDMI.
The 5D Mark III uses a USB port for video output in SD format rather than the mini-jack used on the Mark II.

The signal dropout is inherent to the 5D Mark II hardware and cannot be fully eliminated without either switching cameras or using custom firmware.
Blackmagic converter compatibility varies by model and firmware version, with some models unable to recover from the Canon's HDMI handshake behavior.
Alternative solutions like composite output require accepting SD resolution only on external monitors.
The exact timing and success of workarounds may depend on specific hardware combinations and firmware versions used.