Learn How the Guide Number is Used in Flash Exposure


show more Understanding how the guide number is used provides you with in-depth training on Photography. Taught by Brent Winebrenner as part of the Lighting for Photographers: Flash Exposure Fundamentals show less
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Understanding how the guide number is used

In this movie, we are going to look at how the guide number is used. The test we performed and analyzed in the previous movies gives us a guide number that is unique to our small strobe. The guide number is similar to exposure value because it considers how much light is available based on the power output of our strobe and how much light is required by the sensor as determined by our camera's ISO setting. Remember, when we did the Guide Number test, the formula that we used was guide number equals Flash to Subject Distance times Aperture.

The guide number is constant until you change your ISO. So, once you know your guide number, you can plug it in to the guide number Formula to solve for either Flash to Subject Distance or for Aperture. So, Flash to Subject Distance equals Guide Number divided by Aperture, or Aperture equals Guide Number divided by Flash to Subject Distance. When I'm out shooting, I'm either going to select my aperture for depth-of-field reasons which then dictates how...

Understanding how the guide number is used
Video duration: 4m 38s 1h 27m Advanced

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Understanding how the guide number is used provides you with in-depth training on Photography. Taught by Brent Winebrenner as part of the Lighting for Photographers: Flash Exposure Fundamentals

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Photography
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