• Eric

Does Light Drop-Off Matter?

Yes. It does. Okay, that's the shortest blog post I've ever written. Thanks for reading...




Just kidding. I have some more to say.


What is Drop-Off?

Drop-off is how fast light loses its ability to illuminate things. Imagine a candle in a dark room. Now imagine that you're holding your hand up close to the candle. Then, slowly move your hand farther away. Your ability to see your hand will decrease until you can't see your hand anymore. The candlelight drops off over distance. This is drop-off.


How Fast Does Drop-Off Happen?

The 'speed' at which light drops off is connected to the light's power. A very bright light has a longer drop-off than a dim light. Hopefully, this makes sense. If you have a 100 watt bulb, the light loses its ability to illuminate something within several meters. If you have the sun, the drop-off is much longer. Confusingly, the rate of the drop-off is the same - but the power controls the distance of the drop-off.



Why Does it Matter?

This is incredibly important when using natural light. Here are the two main reasons why drop-off matters when using natural light:


First, you understand how close you have to be to a light source. For example:

  • If you're indoors on an overcast day, you're going to have to move your subject much closer to a window than you would on a bright, sunny day.

  • When using a dim lamp, you'll have to be very close to the lamp for it to work. If you're using a more-powerful window light, you won't need to be as close.


  • Fun Fact: If you have a dimmable light and you want to make your background too dark to see (you have laundry in the background for example...), you could turn the power down and move your subject closer to the light. Since you're turning the brightness down, you're making the drop-off shorter so the light will only have the power to illuminate the subject - not the background.

Second, it helps you know how to isolate separate light sources. If you're in an environment with multiple lights, you can choose to use a single light by taking advantage of drop-off. For example:

  • If you're in a hotel lobby with multiple lights and you only want to use one of the lights, you can position your subject out of range of all of the lights but one.


  • Imagine you're in a room with lamps but you're wanting to use the window light only, you can move your subject closer to the window to increase the relative 'brightness' of the window while decreasing the relative brightness of the indoor lamps.


Understanding Drop-Off is Essential

If you're using natural light, you must acquire a 'feel' for how different lights drop-off. It's the same as if a musician has a sense for how each note sounds. Without this sense of understanding how fast different levels of light drop off, you would be at a severe disadvantage when attempting to use natural light.


To build this 'sense,' choose different light sources in a dark place and take pictures at different distances.


Understanding drop-off is an essential step in your journey to be a natural light photographer.


-Eric

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