Hi, Im new to this and just bought my first LF camera. It came with a Kodak Ektar f7.7 203mm on a Supermatic shutter and after searching almost everywhere I was wondering about two functions on the shutter (marked in red). What do they do? The button is marked with an X on the back.. I read somewhere if I want x-sync it has to be set to F and with some easy modification I can turn it into X? How easy is it? Also read that set to F and fired with electronic flash the flash would be 1/3 to 1/2 stop down. Correct?