I just got my Metabone speedbooster. I haven't tested it outside just indoors. I noticed that when adjusting the iris wheel in a high contrast scene for example in my living room where it's dark with bright light coming through the window I get flickering in the image. I rented a speed booster a week ago and didn't notice any flickering outdoors. Is anyone else having the same problem is this normal?

I figured out the problem it has to with the Green or Advanced operation modes. There'a a small button towards the button of the adapter that I didn't notice. I turned on the camera then mounted the adapter to camera while depressing the button as explained on their metabones website and tada!. You don't need a lens on the adapter while doing this although it helps to prevent smudges. When rebooting the camera you'll need to mount the adapter again to avoid flickering.

Metabones® - Green and Advanced Modes (http://www.metabones.com/smart-adapter-operation-manual/147-green-power-save-mode)