Join Brent Winebrenner for an in-depth discussion in this video Understanding power ratios, part of Lighting for Photographers: Flash Exposure.
At this point in the course, we've discussed how the scales are calculated.…We know what a guide number is and how the math allows us to create equivalent flash…exposures by making offsetting moves with our ISO, our flash to subject distance, and our aperture.…We've seen examples of how it works in a controlled setting.…We'll also see how to apply this information during a live model shoot.…Troubleshooting lighting problem shouldn't be a trial and error, hair-pulling, time-wasting,…iterative process of elimination.…Now, we're going to end our primer on small strobes by introducing power ratios.…
Power ratios are manual settings on the flash that allow you to reduce the guide number…by shooting at less than full power.…They provide another level of control that you can use to make your manual flash more versatile.…Well, small strobes and strobe packs give you the option of shooting at full power…or the variety of lower outputs.…In the case of most small strobes, you can adjust the flash in third stop increments…
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