Zhumell RF645 manual Electronic Flash Photography, Automatic Shutter Speed Adjustment

4. Other Features 4-3 Electronic flash photography

4-3 Electronic Flash Photography

Equipped with a lens shutter system, the Bronica RF 645 features flash synchronization at all shutter speeds. Connect an electronic Speedlight unit to either the hotshoe or the sync terminal located at the front of the camera. When the dedicated Bronica Speedlight RF 20 is mounted on the hotshoe, vital data such as film speed, set lens aperture setting and exposure compensation factor will be transmit- ted between the flash unit, the camera body and the lens, to control the flash exposure correctly.

1. Automatic Shutter Speed Adjustment.

Provided that the shutter speed dial is set to "P" (Program AE mode), the shutter speed is automatically set at 1/60 second for the 45mm and 65mm lenses and the 1/90-second or faster in accordance with the program line for the 100mm lens as the Speedlight RF 20 com- pletes its cycle.

Note: The shutter speed is not automatically adjusted if the camera is in the Aperture-priority AE mode or the manual exposure control mode. Care should be exercised to avoid picking up camera shake if the unit is set to a slow shutter speed.

2. Automatic Lens Aperture and Film Speed Settings

Through dedicated electronic contacts on the hotshoe, the film speed and the lens aperture information are communicated to the Speedlight RF 20. The transferred data calculates the effective shoot- ing range of the Speedlight RF 20 and displays the result on the LCD panel to prevent exposure control mistakes that are common in flash photography. Unlike most external flash metering systems, the Bronica RF 645 / Speedlight RF 20 combination does not place any limitations on lens aperture selection in flash photography. This unlimited utilization of the lens aperture is extremely effective in the adjustment of the distance range and depth of field control in flash photography.

3. Manual Flash Exposure Control

The Bronica Speedlight RF 20 controls the flash light intensity manu- ally in six steps from 1/1 to 1/32 in one-stop increments. Apply this manual flash exposure control for accent flash illumination, e.g.: to highlight a model's eyes, to illuminate the subject with constant flash power regardless of the ambient illumination or to illuminate a sub- ject located at a specific distance. The set lens aperture and the prop- er photographing distance range displayed on the LCD panel of the Speedlight RF 20 are very useful in determining the manually con- trolled flash exposures.

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