I'm using a Sony 28-135mm lens on an FS5. They seem very compatible but often, mid-shoot, the iris will cease to become adjustable from the camera - the isis wheel on the camera doesn't work, nor does the auto iris button. You can only adjust it on the lens wheel.
Then miraculously the controls will start functioning again for no apparent reason. Very annoying.
All the while the focus controls remain working fine. Just the iris that's the problem.
Can someone please throw some light on this. Thank you in advance.