KEY CONCEPTS OF
FLASH PHOTOGRAPHY
By Anthony Bianciella
Flash
PUTTING LIGHT WHERE YOU WANT IT
FLASH
F U N D A M E N TA L S
• ISO
• Distance
• Power
• Size/Modifiers
• Aperture
• Shutter Speed
ISO
SENSITIVITY
ISO
• Just as in all types photography, ISO affects the camera’s sensitivity to light
• Raise ISO = Raise sensitivity to flash
• Lower ISO = Lower sensitivity to flash
Distance
I L L U M I N AT I O N O N T H E S U B J E C T
D I S TA N C E
• Light energy falls off quickly (inverse square law)
• Example: Double the distance = 1/4 of the illumination
• Moving closer or farther changes the amount of light
• Moving also changes the hardness/softness of light
• Using fall off theory, even out light for groups
Power
ENERGY LEVEL OF FLASH
POWER
• The amount of energy in each flash burst
• More power = brighter light
• Less power = dimmer light
• Like the dimmer on a chandelier
• More power requires more time to recycle
Size & Shape
QUALITY
SIZE & SHAPE
• Size of light relative to the subject controls quality
• Smaller light sources = sharper, harder shadows &
more specular (shiny) light
• Larger light sources = softer, less-defined shadows &
less specular highlights
• Shape contours how light hits subject
Aperture
FLASH LIGHT EXPOSURE
APERTURE
• Controls the amount of light entering through the lens
• Smaller aperture = less light getting in
• Larger aperture = more light getting in
• Also controls depth of field
Shutter Speed
AMBIENT LIGHT EXPOSURE
SHUTTER SPEED
• Controls the amount of ambient light in exposure
• Slower shutter = more ambient light
• Faster shutter = less ambient light
• 1/125 - 1/160th should eliminate most ambient light
• Has no effect on flash exposure…
until the max flash sync speed is reached
MAX SYNC SPEED
The second curtain is already closing before the flash fires
Second curtain blocking some flash
HIGH SPEED SYNC
• Enables using a flash when shutter is faster than max
sync speed (i.e. faster than 1/200th or 1/250th of a
second)
• Flash fires in pulses to ensure light is added to the
exposure before the shutter closes
• Uses more power
• Usually only available when using name brand flash
units but some off-name brands too