Figuring out flash exposure

People who are very talented in ambient light photography may have very little knowledge with electronic flash. There are several facets to flash photography:

• • the jargon

  • the terms used in the camera's menus

  • the limitations on the power of the flash unit you have

  • the impact on the exposure if you

    • use a flash unit that is not powerful enough

    • use the flash in premises that are so big or have dark surfaces that light is quickly dissipated

    • use too low an ISO or too dark an f/no or too fast a shutter speed

    • stand the flash too far away from the subject

    • divert the flash light using bouncing, diffusers or softboxes

There are two exposure calculations.

• • Stage 1: The ambient light calculation - ISO x shutter speed x f/no x reflected light from the ambient light sources

  • Stage 2: The flash light calculation - ISO x f/no x flash to subject distance x reflected light from the flash

More info:

• https://nikonclspracticalguide.blogspot.com/2008/01/nikon-flash-two-separate-metering.html

• http://dptnt.com/2009/01/nikon-creative-lighting-system-practical-guide/

In contrast, with ambient light photography, you can see the light yourself, you can see exposure emulation in liveview (and adjust compensation), the camera's metering will indicate numbers, you have live histograms and blinkies - there is no end of exposure assistance even before you press the shutter release.

• My article: Using TTL Auto and HSS (OM-D E-M1 Mark 1 and Nissin i40 mounted on the camera)

• Petapixel article on the 1/x squared light fall off rule