I have an X-T30 that I'd like to use some of my old Canon FD lenses with. I have the adapter and made the recommended menu changes (e.g., shoot with no lens, set focal length.) However, I'm not sure how to do the metering once they are in place. I understand it is manual - but does manual mean I make settings on the lens according to what my viewfinder manual exposure is telling me, or do I need to basically use a light meter/external source to determine the exposure setting and adjust accordingly?