Always point the incident dome to the lens for Incident light measurements. This will give you an 18% grey reading without a grey card. This type of measurement is very accurate. Remember to flag off the rear kicker with your hand, otherwise your film will be underexposed. When using a reflective spot meter, remember if you cant use an 18% grey card, use the meter to make several measurements from highlight to deep shadow, use the zone system to place your exposure in the middle of the zone, this will give you an even exposure. If you want to crush the blacks, stop down, if you want to open up the mids and highlights, open up some. When exposing film you have around 12 stops of lattitude, but always take into consideration your final output when exposing, meaning, you wont get 12 stops on a 2k transfer, so you will need to reduce your lighting ratio to match your transfer, meaning shoot a film test with the lab and get a best light 2k or 4k transfer to see what they see.