AF noise with the 24-70 EF

[Qstorm]

I have a 24-70 f/2.8 EF lens on my C70 Cinema camera using a Canon EOS EF - RF adapter. The autofocus causes substantial noise. But when I put the lens and adapter on my R10, there’s no noise at all. The research I’ve done thus far suggests the adapter is not at fault, what would cause the difference? Also, it was suggested that I update the firmware on the adapter. Any thoughts?

[deebatman316]

What is the lens aperture set to. Older EF lenses have very loud aperture motors and AF motors. So which EF 24-70mm F/2.8 do you have. Canon made 2 models of it. The original and a version 2. Also do you have Continuous AF/ Preview AF on. That could also be a factor too.

[Qstorm]

Good questions that I hadn’t considered. I have the older lens and I shoot wide open at 2.8 to let the background go soft. I do have continuous AF on, I’ll check that, thanks. 

[Waddizzle]

Demetrius’ observations about older lenses having noisy motors is spot on.  Many of the older lenses released prior to 2009 are not compatible with the advanced focusing and tracking technology made available by Dual Pixel SF sensors, which were introduced in 2009.

When the cameras equipped with a Dual Pixel AF sensor detects an older lens, then some advanced AF features are disabled, such as variable AF tracking speed.  

You could be hearing the difference when this tracking feature is enabled and when it is disabled.

In other words, the RF mount C70 may not be differentiating between lenses being fully compatible and not fully compatible.  

[ovdmse]

I have the first version of the EF 24-70 2.8, purchased in 2009, which makes a strange squeak when focusing in servo mode on the P5.