Since ordinary slave units will not work with most digital cameras (because these cameras use a very rapid series of pre-flashes, that trigger the slave prematurely), Wein is now offering the Digital line of slaves. A typical slave unit will fire on the pre-flash it senses while the digital camera captures the image on the last flash. These slave units are specially designed to only be triggered by the correct flash sensed by their built-in optical sensor and circuitry, thus solving the digital camera flash problem. Standard PC sync connector, plugs directly into Vivitar 283/285 or connects to any other flash via PC cord.