E-P2 Alternate Flashes In Fill Flash Mode

<p>I am calibrating my T-Series flash units for use with my E-P2. I have established that the sensor is several stops more sensitive to OM flash than is film.<br>

I am reversing the control plate at the back of my T-1 control unit and selecting the O 4 setting and that gives correct exposure at 1:1 macro with lens set at f11 (manual) and ISO 100 and the Twin T28 flash is correctly placed and aimed.<br>

To overcome any tendency for the E-P2 to decide whether of not to fire the flash, I have set it to fill mode and the camera to M or S, and the shutter speed to 1/160.<br>

To further discourage the camera from not firing the flash I work in subdued light.<br>

The T-1 is on the E-P2 hotshoe.<br>

The question is:<br>

The first shot at a subject fires the shutter but not the flash, although the flash exposure confirmation light flickers to confirm the (non-existent) flash exposure was correct. The image recorded is black. The next shot fires the flash and it gives correct exposure. It is not some flash firing at random and some not. It is strictly alternate.<br>

What is going on, or not going off?</p>

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