The Inverse Square Law Of Light - BYU Photo

BYU Photo's Nate Edwards demonstrates the Inverse Square Law and how you can use it to level up your studio lighting. By using the physics of light, Nate will teach you how to master light falloff for both portraits and group photos.
Photographed with the Canon R5 and Profoto D2 and Pro 10 Studio Lights.
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[@Eduardo_Aguirre]

The best video about “The Inverse Square Law” by far, period. And I watched quite a few.

[@byuphoto]

Thanks Eduardo! We hope it becomes a good resource for others.

[@ChritsianBucic]

By far the best one, and straight to the point!

[@zavoina]

Truly one of the better explanations I've seen.

[@byuphoto]

thank you! Hope it was helpful!

[@pc5447]

This has to be the best illustration I’ve seen Thanks!

[@byuphoto]

Thanks for watching!

[@gustavolopez5403]

I’ve seen other videos explaining the law but didn’t grasp the theory quite well. Until now. Thank you!!

[@byuphoto]

So glad it was helpful!

[@ChuckSeayII]

Great tutorial! Very well done explanation on the how, where, and why to position your light and subject and how light reacts across distances! I have heard this for years but this video is the one that clears it up for me! I'm a very slow learner LOL! Thank you so much for sharing this! It's a true gift! Now I know I will do so much better lighting stuff!

[@byuphoto]

So glad this video was helpful Chuck! Thanks for watching!

[@DMATcyt]

Wow..best explanation I have seen/ heard! Definitely subscribing. The test of true comprehension is when you are able to teach it to someone else, your tutorial has enabled me to accomplish this. Xie xie ni

[@byuphoto]

So glad it was understood and helpful. Best of luck!

[@graememacdonald1088]

Excellent video with really useful exemples!

[@byuphoto]

Glad it was helpful!

[@Pattern_seeker202]

Amazing information

[@7189k]

Well done. Finally understand the concept!

[@byuphoto]

So glad to hear! It makes all the difference.

[@mimosz8097]

love this explaination!

[@davegalegor2865]

OUTSTANDING Information.

[@byuphoto]

So glad it was helpful!

[@azppmd]

Brilliant and clear explanation. So many amazing videos from BYU Photo.

[@byuphoto]

Thank you!

[@johncalhoun4806]

I wish this was posted a couple days earlier because these valuable tips and explanations would have helped in a session I was trying to improve using off-camera flash. But all’s not lost - knowing what my problem and challenges were allowed me to quickly find the correct solution, which is all contained in this video! Knowing where I went wrong now, won’t make those mistakes again! Thanks BYU Photo!

[@byuphoto]

Sorry it wasn't posted a couple days earlier, but at least now you knew which questions to ask in figuring things out. Glad the video was helpful!

[@dandaninglis]

Awesome video!! Great explanation of the concept with practical examples showing how to utilize it. Top notch!

[@byuphoto]

Thanks Dan! We hope it is a good resource for others.

[@SteveMitchell-bt8ez]

I feel like you might have mentioned that those numbers don't have any similarity to the corresponding f stops you would use.

[@ldouglass6]

Boom! Mic drop Thank you

[@rahulaldar8531]

wow nice video sir😍❤️🔥

[@byuphoto]

Thanks! Hope it was helpful!

[@roncournoyer2792]

Fantastic info, always good to have a refresher on the basics once and a while. Your videos always help us bring oout the best in our shoots. Little off topic question, as we';re redoing our studio as we speak. What are you using for the backdrop and cyc wall and floor in your studio. Looks like it is one piece of material and that would be helpful to know as we build our out. Thx!

[@byuphoto]

we used Pro Cyc and they are the best. www.procyc.com/?gclid=Cj0KCQiAgqGrBhDtARIsAM5s0_nHasGqGt94zAGr_1rvZHtPVc7EGq-W68oNxdH9UD33rRCJgPRm

[@dance2jam]

I've seen many basic discussions of this, but yours was to the point and well subsidized by visual examples. I've only been using a strobe for 4 months, but I read up on this and put it into practice nearly immediately (testing it out visually for myself). The one thing I haven't seen anyone do yet, is talk about the limitations of the inverse square law and exceptions of when it doesn't really apply. Question: "Larger small groups" - what is this? and how would using a small light source further away (harder light) be better than a larger source closer, modified, and feathered? Thanks for an excellent video and taking the time to produce it.

[@byuphoto]

great question. the reason i say a small light source farther away over a large light source closer for group photos is because of the inverse square law. a large light source close will not light a group of people evenly. it is all relative to the size of your light source. the larger your light source, the further back you will need to place it to get a more even falloff. the 1'-10' illustration is just an example, not exact. the distance of falloff changes relative to the size of the light source. the smaller the light source, the shorter the distance of falloff. the larger the light source, the further the distance of falloff. you can for sure feather the light as you mentioned. this is just an easier way to get a more even light across a larger area (like for a group photo). I hope that makes sense as i wrote it out. it does in my head haha

[@dance2jam]

@@byuphoto LOL - Yes, I followed what you were saying. Got it.

[@dennisjones5579]

Great video, The graphic showing the percentage of light fall off with distance was very helpful. I have 2 questions, which may be the "stupid" questions of the day. First, you estimated the changes needed either to the light source or camera to be 3.5 stops, the second time "about" 3 stops. How did you determine that? Was that more of an intuitive "knowing" based on experience or was there something else? Second, did you make the changes in this video to your light source or to your camera? Thanks, and again, well done.

[@byuphoto]

Great questions. To the first question, I made sure I knew the exposure before we started filming so I could have it in my script. But once you do it over and over, you are able to get a pretty good general feel for the amount of adjustments to make. To answer the second question, I made the adjustment on the power of the light. I typically keep my camera settings the same and just compensate with the power of light when I am shooting.

[@judesonataisi4503]

I really understood this

[@byuphoto]

so glad to hear!

[@mikeletson1962]

The sun is a perfect example of light dispersion at longer distances. It so far away that its light illuminates an entire half of the earth relatively evenly.

[@byuphoto]

yes, perfect example!

[@JoshuaBrittonAndrews]

What about the size of your modifier, how does that play in?

[@byuphoto]

great question. The smaller the modifier, the distance and amount of the light falls of is much shorter. The larger the modifier, the distance and amount of light fall off is larger. Hope that makes sense. That is why with a group photo you would need to put a larger modifier further away than you would a smaller modifier, which you could keep closer. It is all relative on the size of the light source.

[@LupinYonderboy]

Did he lock that stand before he walked away ? hmm.. ;-)

[@MrKravmagadude]

"and what the inverse square law tells us, is that the model has fantastic long legs."