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Old Apr 21, 2010, 5:43 AM   #4
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378

With a dedicated flash like your Vivitar, the extra pins are normally used for communication between the camera and flash (i.e., signaling telling it to fire a preflash, how long the main flash burst should be based on how much reflected light the camera saw from that metering preflash, etc.).

Most dedicated flash models will still fire if you short the center pin and outside of the foot together. But, they're really not well suited for use as a non dedicated flash using something like that wireless setup you have (as you'd need to use manual power settings to control the flash, since there is no proprietary signaling going on with a non-dedicated wireless setup like that).

Otherwise (if you don't use manual power settings), most dedicated flash models will just fire at full power. Another option would be to use a flash model with a non-TTL Auto mode (Sunpak 383 Super, Vivitar 285HV, etc.) with a built in sensor to measure reflected light during the exposure, terminating the flash output when it sees enough light for the aperture and iso speed set. That would require setting the flash and camera to match for ISO speed and aperture. But, that can be easier than trying to use a flash that's manual power only (which is basically what you have with that Vivitar using that type of Wireless setup).

With that flash, you're probably just fooling the flash into thinking it saw some kind of signaling on another pin using your kind of technique (the wake functions are probably not trying to interpret that signaling), even though you won't have any real control of the flash power from the camera via that type of wireless setup.

Now, you can buy wireless setups with full TTL control for use with dedicated flash models. For example, Pocket Wizards are popular with Nikon and Canon users. But, they'll cost you more compared to the type of setup you're using now.
JimC is offline   Reply With Quote