Portable flash
• powered by batteries
• typically high output
• sophisticated exposure control
• multi-featured and many accessories
• can be dedicated to camera exposure control
• electronic flash can be powered by either mains power or by battery
Monobloc Portable Flash
• powered by mains supply
• constant high variable output
• lots of different accessories available
• convenient for location work
• expensive
Electronic Flash - Studio Flash
• powered by mains supply
• very high variable output
• many accessories
• extremely versatile
• very expensive
• a guide number is a measure of the power output of a flash unit. This number is then used to calculate correct exposures; higher the number = higher output
• ie canon 580EX gn = 58 480 = 48 etc
•use of the guide number to determine exposure
(GN) at ISO ???:
f-stop = GN/subject distance
• intensity of the flash decreases as subject distance increases
• The 35mm focal plane shutter has two ‘curtains’, one that opens the ‘window’ and one that closes it.
• Flash is triggered when the first one has opened fully.
• For there to be complete exposure the second ‘curtain’ must not have started to close before the flash is triggered.
- typical upper limit of between 1/60th and 1/250th sec
- this is the fastest speed that can be used whilst still having the shutter completely open
Canon.
Loves using straight on, full power, flash. Never fail 580EX II portable flash.
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