Flash photography tip: Forget the inverse square law

Thursday 13 June 2024, 20:02 by Elja Trum | 2,676 views | 3 comments

This article was translated from Dutch with the help of AI. Read the original.

The inverse square law seems very complicated, but as far as I'm concerned, you don't need to know the maths behind it at all. In fact, you can forget the square law completely. What matters is that you know what effect it has and how you can use it.

Sophia- f/7.1, 1/30s, 100 ISO @ 32mm
The inverse square law says that when your subject is twice as far away, you only have a quarter of the energy (flash power) left.

Or, put another way, when you halve the distance between your flash and your subject, your flash light becomes 4 times as powerful.

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About the author

Elja Trum is the founder of Photofacts and online photography course website Photofacts Academy. He has been writing about photography since 2006. Elja is also the author of (Dutch) books on composition, black-and-white photography, flash photography and portrait photography.

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3 comments

guest wrote on Tuesday 18 June 2024 at 12:19 | reply
Voor beginners is Inverse Square Law ofwel ISL (handig voor filmpjes op youtube) essentieel. Ik zie regelmatig foto's waarvan de haren je te bergen reizen omdat de essentie van flitsfotografie niet geleerd is. Creatief omgaan gaat pas lukken na flink geoefend hebben met allerlei soorten lichtvormers. Promoten om ISL overboord te gooien is m.i. geen goed onderwerp voor dit platform.
This comment was written in another language and has not been translated yet.

Elja Trum wrote on Tuesday 18 June 2024 at 13:18 | reply
Zoals ik aangeef in het artikel; het gaat erom dat je weet wat licht doet.

Het naampje 'de omgekeerde kwadratenwet' voegt weinig toe. De term en de wiskunde maakt het onnodig complex.
This comment was written in another language and has not been translated yet.

Koen van Venetië wrote on Tuesday 18 June 2024 at 15:43 | reply
Ik flits nooit met mijn Canon camera's en ik fotografeer veel in donkere ruimten.
This comment was written in another language and has not been translated yet.

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