Hello everyone! i have an odd flash problem that i can't figure out. I recently purchased a Vivitar DF450mz. I am not sure if i am doing something wrong or the flash unit is faulty. I am using it in Program Mode with TTL fully on. I use the slow sinc mode or rear sinc mode for indoors and flash compensation function (+/-) to get the exposure to look the way i want to. But that's where my problems begin. Sometimes after a few shots, sometimes out of the blue the flash goes off at full blast, overexposing the picture. Usually when that happens turning the camera and flash off and on makes things work the way they should again... What is going on???