CR7 Basics Photography_ Light_p90-91

Flashgun is a most versatile light source; powerful yet lightweight. The advantages of flashgun: their light can be bounced or diffused just like any other light and electronic flash is balanced at daylight colour temperature. The disadvantages is that the exposure is only correct for a set distance, which can produce dark backgrounds and overexposed foregrounds. Moreover, accessory flashguns are more powerful and can be used both automatically and manually.

There are three key specifications for any flashgun – guide number (a measure of flash power for a given film speed), recycling time (the speed to recharge between flashes) and coverage  (the angle that the flash beam covers).

Guide number= aperture × distance

Flash synchronisation: the correct timing of the flash to illuminate the whole film frame or digital sensor.

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