Explain flash delay settings on early Ruski cams.

[phototone]

Which delay setting is the correct one to use electronic flash on the 1950's Russian/Ukrainian rangefinders that have flash sync. There is a ring around the shutter that has 0 to 25. I tried 0 and it wasn't right for electronic flash. Got falloff on one side.

 

[Stanton]

The various delays were for flash bulbs, which took various amounts of time to reach full brightness. The delay for an electronic flash is 0 (zero), because it reaches maximum output essentially instanteously. However, with a focal plane shutter, that means that the shutter curtains must be fully open when the flash goes off, and in the early focal plane shutters, that means a very slow shutter speed. So, set the delay for zero and the shutter for 1/25.

 

[phototone]

Flash sync

Flash sync

Well, you see, I thought that O was the correct setting also, and I got a fall off on one side. I tested the camera later by taking off the back, and looking through the back with the camera shutter aimed at a large flash soft box, of course using 1/25th second, and firing, and you can definately see a dimming of the light on the left (the slide the shutter curtains end up at, after opening and closing). I tried maximum, or 25 (delay) and the light was even all across. (To my eye)

My theory is the 0 setting triggers as the first curtain starts so the flashbulb will be up to maximum output when the shutter is fully open. The 25 triggers the flash when the first curtain is fully open. It "delays" the flash until the first curtain travels across, and it fires before the second curtain starts closing.

Of course I could be wrong, and my camera could be all wicky wacky.

 

[Stanton]

Obviously go with what works. But I know my old Russians work with 0 delay, and I think in theory that 0 is correct.