Join Brent Winebrenner for an in-depth discussion in this video Understanding exposure basics, part of Lighting for Photographers: Flash Exposure.
As you know, exposure is a delicate balancing act that requires the alignment of four distinctly…different yet interrelated variables that include Illumination, Sensor Sensitivity,…Shutter Speed, and Aperture.…The first factor that we're going to consider is brightness or luminance.…Luminance describes how much light--either from a natural source like the sun or an artificial…source like a small strobe-- is falling on the subject.…The second variable, Sensor Sensitivity, determines how much light is required to record an exposure.…
The ISO setting determines the sensor's sensitivity to light.…The setting controls the amount of amplification that is being applied to the digital data…that is collected by the sensor.…When you are shooting in low light, or with an underpowered flash, you can increase the…numerical value of the ISO to increase the gain or amplification.…As this gain increases, less illumination is needed to achieve the same exposure.…Together, luminance and sensor sensitivity combine to determine what in available light…
Even with today's automatic flash systems, there are good reasons to understand how flash exposure really works. Brent details these concepts in this course. The course describes how to calculate the true power of your flash and how to modify its output to match your needs, a technique that can extend battery life, reduce recycle time, and provide exposure control that is more predictable than fully automatic modes. The course concludes with several shooting scenarios during which Brent explores the creative use of gels, reflectors, and other light modifiers.
- Understanding exposure basics
- Reviewing aperture, ISO, and shutter speed
- Adjusting strobe power and flash to subject distance
- Finding the guide number of a strobe
- Making calculations based on ISO
- Understanding power ratios