Hi there I've just acquired a wireless flash trigger, Canon 430EX flash and a PC sync cable. My Mamiya C-220 has an "X" mode for flash sync that will sync all the way to 1/500 (leaf shutter for the win). However, I have no idea how to judge and set the flash intensity against a given aperture / exposure setting. I have no flash meter, but do have an old selenium light meter if that helps (I would imagine not in low light though, when the needle won't budge). Any pointers on how I go about setting the flash up please?