They are used on the old style cameras like you see in the movies, used by the guys that would wear a fedora hat with a card that says PRESS in it, with the huge flash bulb. The tube is attached to the side of the camera vertically, and acts as a handle. It has a large bowl (maybe 8 inches across) with a flash bulb in the center, facing toward what you are taking a pic of. The tube has the switches on it that control the flash, and there are components inside that control the timing of the flash so that it goes off at the right moment that corresponds with the film. I guess the timing was much more critical with the old type of film, and the required shutter speed. Hence the name "flash synchronizer." I don't know of anyone who makes them currently. The only ones I know of that are available are all vintage from the 1940s and 1950s. Fleabay is a good place to look. I snatched up mine there, and got a pretty nice package from some lady:
Originally posted by Lucksy31:
OK, I have to ask about the "History" of these flashtubes. What were they actually used for, and are they still actually made? Is the best place to get them EBAY?? Lastly, is there one inside the ROTJ version, but just covered up??