Okay nerds, I got a good one. On the side of the old Acme is a lever for the flash sync. I KNOW for sure my flash is working and I tested the same f/stop shutter combo on my digital camera. On the side it says M BLU, F WH, X RED.
I thought many years ago I've used this lens with a flash and it kinda worked. I think I used it with flash outdoors as a little fill.

I kinda remember that one of the settings is for old school flash bulbs aka, WEEGEE style, and it doesn't go off immediately. So if I were to use the Acme Shutter with bi-post (yes, I have bi-post cable to a flash trigger), it needs to be on the X RED settings right?


I thought it didn't matter because all our LF shutters sync at all speeds. Am I wrong? I think it was set on the Blue (M) and for the life of me, I processed film and they were blank thinking it didn't sync.