Some flashes, cameras and wireless flash triggers (such as Canon ST-E2) have a near infrared AF assist light that is invisible to the human eye.
I understand that its AF assist light works at least with the dedicated phase-detection autofocus sensor in digital SLRs.
However, nowadays many mirrorless cameras use sensor contrast detection or dual pixel autofocus. In addition, if you take pictures in live view, DSLR cameras can also use sensor-based autofocus.
However, should not imaging sensors capture only visible light and not the near infrared?
So, my questions are:
- Does a near-infrared AF-assist lamp work with contrast-detected autofocus?
- Does a near infrared AF assist lamp work with Canon's dual-pixel autofocus?