Metz Mecablitz 45 CL-4 - Manual (Page 49)

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11. Exposure Corrections
The automatic exposure systems are based on a subject reflection factor of
25%, this being the average reflection factor for subjects shot with flash.
Dark backgrounds absorb a lot of light, while bright backgrounds reflect a
great deal of light (e.g. backlit scenes), thereby resulting in subject overexpo-
sure or underexposure, respectively.
11.1 Exposure correction in automatic flash mode
To compensate the above mentioned effect, the exposure can be corrected by
opening or stopping down the camera’s aperture. With a bright background
the sensor of the flashgun cuts out the flash too soon with the result that the
actual subject is too dark. With a dark background the flash is cut out too
late so that the actual subject is too bright.
Bright background:
Open the camera aperture by 1/2 to 1 f-stop
(e.g. from f/5.6 to f/4).
Dark background:
Close the aperture by 1/2 to 1 f-stop
(e.g. from f/8 to f/11).
11.2 Exposure correction in TTL flash mode
Many cameras feature an adjusting element for exposure corrections that
can also be used in TTL flash mode.
Please observe the corresponding explanations in the Operating Instructions
for the camera.
Here, exposure correction by changing the aperture on the lens is not possi-
ble. This is because the camera’s automatic exposure system will regard the
changed f–stop as a normal working aperture.
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12. Care and Maintenance
Remove dust and grime with a soft dry cloth, or a silicon-treated cloth. Do
not use detergents as these may damage the plastic parts.
Forming the flash capacitor
The flash capacitor incorporated in the flashgun undergoes a physical chan-
ge when the flashgun is not switched on for prolonged periods. For this rea-
son it is necessary to switch on the flashgun for approx. 10 minutes every 3
months. The battery must supply sufficient power to light up the flash-ready
light within one minute after the flashgun was switched on.
13. Technical Data
Guide numbers at ISO 100/21°:
For meter systems: 45; for feet systems: 148
6 auto working apertures at ISO 100/21°:
f/2.8 - f/4 - f/5.6 - f/8 - f/11 - f/16
Flash durations:
• approx. 1/300...1/20000 second
• In M mode approx. 1/300 second at full light output
• At 1/2 light output approx. 1/1000 second
• At 1/4 light output approx. 1/2500 second
• In winder mode approx. 1/10000 second
Photosensor measuring angle: approx. 25°
Colour temperature: approx. 5600 K
Film speed: ISO 25 to ISO 1000
Synchronization: Low-voltage thyristor ignition
Number of flashes:
50*...2000 NiCad battery
100*...2600 with alkaline-manganese batteries
140*...3600 with high-capacity alkaline-manganese batteries
(*with full light output)
703 47 0149-A3 45CL-4 14.03.2006 10:08 Uhr Seite 49