Peter Hurley's explanation of the inverse square law confused the hell out of me... Mark's teaching of it was so simplified I grasped the concept and technique of it almost instantly. Thank you KZfaq for making it possible for me to CHOOSE my photography instructors, and thank you Mark for making this complicated thing so simple:-).

Mark, I can't tell you how thankful I am for you and your team for these videos!!! I am a professional wedding photographer, but I only got into studio photography last year and these videos are absolutely fantastic. Such friendly teaching and so well edited and easy to understand. The videos have really enriched my photography experience, given me more confidence and brought new enthusiasm to try out different things. Thank you so very much!

by far the best explanation of the inverse square law. thank you. your a fantastic instructor.

Excellent, excellent video. I was aware of the inverse square law however seeing your demonstrations really help clarify it. Thanks so much for doing this series and thanks to Adorama for sponsoring it.

You're the best Mark! This video is really helpful. You make inverse square law very easy to understand.

Mark, in my many years of photography, this is the best explanation *PLUS* practical application and demonstration of falloff I have ever seen. Great video! Thank you!

Mark, this has got the be the best tutorial of all the series. Thanks so much for breaking it down with examples because it really made it easy to understand the concept. Thank you very much!!!

As an artist, I found this quite informative. I may not use fixtures to achieve a specific focus, but the light on my subject must follow the same "law" if I wish to achieve a desired effect. Nice job explaining this and showing exactly what to expect. Thank you and your lovely model for explaining, posing in position and for sharing this!

Wow! That was the clearest explaination and example of the inverse square law I'v ever seen! Bravo to you Mark!

Great job, Mark! Clear, concise and wonderful examples.

Mark.. this is unreal.. Ive learnt more in 3 episodes than in 4 weeks of photography Class! Brilliant

this is the simplest and important class i have witnessed.

Even though I knew this theory for years, I am amazed to find that often I struggle with light and totally forget about this important inverse square law concept. Thanks for making this great video to remind me once more!

I'm a photographer with a lot of years behind me ( over fifty years in fact) , and I used to manage a photo lab in Blackheath village in South east London. I had occasion to try and explain to a customer exactly why his photos taken at a concert hadn't come out as well as he expected. He'd shot some images of the stage from around 50 to 75 yards back, naturally the images ( of the people on stage ) were not very good since he was only using a compact camera. The problem came when trying to explain why the flashgun was not powerful enough....after several attempts at explaining and drawing diagrams ( none of which worked ) I asked him (politely) what his mathematical ability was like. "I'm a professor of mathematics...its what I do" was the answer. I turned and gave him a little smile , 'Inverse square law, the power of the flash diminishes over the square of the distance'. Only to get the reply "Why didn't you say that in the first place"! Then he realised what he said and burst out laughing.

and you can see that there is a difference 11:19 ---just messin around!!!! great job mark!

WOW! Mark you are the best!!! tou explain this so well... keep up the great work man!!!

Mark, Thank you sir for your very informative video, I find you very easy to understand. I really appreciate all your efforts in making these videos and I look forward to watching all of them. I definitely will consider making my next purchase from your store. I have already learned a lot from you, I thought I knew a lot about photography before but these vids show me how much I need to learn. Thank you, Eric

wow he always explains things so clearly! I always learn much from his tutorials!

Best explanation I've seen so far.

I am just starting out my professional photography and THANK YOU Mark :D You are a fantastic teacher and I look forward to more video's from you.

Wow - these Mark Wallace videos are some of the most informational and helpful videos on photography you can find. Thanks Mark! Thanks Adorama TV! Subscribed!

hi Mark this is the best thing i came to know really great , earlier i was bit confused with this Inverse square law but u made us understand with real life examples WOW AND THANKS HATS OFF

Thanks, Mark. I've been reading up on it, but seeing it in action just cleared up the entire theory!

Ideal episode! Thanks, Mark!!!

one of the most informative videos ive watched in quite some time.. model and photos are beautiful.

Best explanation so far.

Great explanation of Inverse Square Law and awesome video with scenarios. Thanks!

Mark your videos are amazing man. Thanks a lot

ur the man, mark, very informative, can`t wait for the vid. thanks.

A complication to the inverse square law is that it is only totally true for point sources of light. Close to a large softbox, moving from 1 cm away to 4 cm away will not reduce the exposure by a factor of 16 - it'll be pretty constant. This deviation from the inverse square law will remain prominent until you're about 1 diameter of the softbox away from it. After that, it'll start to behave itself more. Perhaps a better way to put that is: The light from a softbox is fairly constant brightness out to about half its diameter, and once you're beyond about 2 diameters the inverse square law will hold well. While in between the light will blend between the constant high brightness and the inverse fall off. And to complicate things - this is for direct on-axis use of the box. For a more glancing pass of the box's output, the inverse effect will start to kick in a little earlier. If you buy me a beer, I'll write out all the equations. But nobody even vaguely sane would want to read them :)

Thank you Mark! I don't even have a flash yet, but I do have a reflector (got it after seeing your vid on that) and I can't wait to try this out!

i am already subscribed best tv in world... mark is the best!

Great stuff! I really learn a lot! Thanks Mark!!!

I love the way u explain the things in easier way.. thanks tons!!

Excellent and useful tip to make the best of a simple light setup

Learning has occurred. Great video!

Right. area follows rules of square. If we were measuring volume we would be looking at cubed math and really make things complicated. I like it!

Man, I always learn so much from the videos on this channel! Thanks for these videos. Really appreciate the clear explanations :)

WHAT WAS GOING TO BE OUR LIVES WITHOUT MARK WALLACE??? " NOW, WHAT I'M GONNA DO IS..." LOL :) THANK YOU VERY MUCH MARK!!!

This is useful and good info video. Thank you so much for sharing Mark

That's the simplest i've seen it put.. thanks Markorama!

Thanks a lot Mark! Quite clear explanation!

Great explanation Mark, thanks

Thank you so much for your very comprehensive explanation practical demonstration.

Very interesting Mark, it's good to know how it actually works

Your going to have severe shadows on the background if you place the subject(s) to near the background, and the light far away from both. The lightsource has become smaller, therefore you get a hard light, when you need a soft light. The best tip is to have a main light (for the subject), rim light for the hair and partly separation, and a background light for the separation it self.

lol i love youtube for these past 6 months i have been getting a free education in photography.

Thanks for such a clear explanation!!!

This helped me. Free education, people pay for this.

Mark you rock!

Very nice way of explaining concepts Mark!

Thanks Mark for this video

Very nicely done video. One suggestion... always put the neck strap around your neck. I learned the hard way when I let my boss use my camera. He didn't have the neck strap around his neck, and the camera fell to the floor. The pentaprism shifted- cost to fix, $225! Lesson learned. (He graciously paid for it!)

This one was very interesting. Thanks for the great explanation, Mark!

Very helpful! Thank you Mark!

thank you God 4 Mark !!!

As brilliant as always! thx

amazing video. super easy to understand!

awesome video, once again!

Sam you are great !!

sam look nicer in this hair cut than longer hair ,she is so cute

Great! Thanks to you I understand this clearly!

This was incredibly helpful. Thanks Mark!

Great explanation and demonstration. And I'm in love with Sam

please continue the great work. most photographers would charge money for videos like this.

wow you are really good at explaining mark well done :D keep up the good work

Great video... I'd never heard of this. Now I know. :) Also, Sam got a haircut! It looks great! I'm surprised no one else has said anything about it yet, haha.

This helped me write a discussion paper I had in Business math about fomulas..Thanks

Loved it!

Awesome instructor.

Fantastic video.

Thank you very much, very clear!!

great and informative video Mark. I was wondering if you can share with us the settings for the shots, unless you have a video that talks about that in details. Thanks and look forward to more videos

Thank you so much for this video, an amazing explanation.

@epos85 It depends on the size of the light source. If for example you use a huge Octobox as in this video & the subjects 20 feet away & close to the background the light will be soft & cause no shadows. See Marks other video Ep 64 where he demonstrates it.

very interesting, you do a good job in explaining too

Beautiful sam

Fantastic!! Many thanks

Sir,A good tutorial. Thanking you.

Imagine a sphere of radius 1 foot around the light source, and compare that to a bigger sphere of radius 2 feet. The surface area of the bigger sphere is not twice, but four times the smaller sphere (because the area is proportional to the square of the radius). So each unit area in the bigger sphere is absorbing only 1/4 of light as that in the smaller sphere. Hence the inverse square law.

good job, really well done.

If only you were there to tutor me through Algebra 2 last year ;( Seriously, you're an amazing math teacher hahah

thank you ... was very very clear..

I like Sam's short hair style!

Great demo. Thanks

very very very useful vid ....thanks so much

It works even with no metric system at all: double the distance, and you get 1/4 (inverse of 2 x 2) the light intensity, triple the distance, and you get 1/9 (inverse of 3 x 3) the light intensity, and so on...

Thanks for making this video!

Great info thanks!

Many Thanks!!

this was so helpful! tks

very well explained thank you Sam

been waiting for a week for you to upload this episode, you should do one on one twice a week =]

Awesome!!

Well done!!!! :)

Hello Mark. I have a question about the inverse square law. I get that the intensity of light from a light source varies according to that law but what I don't get is why, seemingly, the light from the subject does NOT. I.e. the camera can move closer to or away from the subject and yet the exposure will remain perfectly adjusted and balanced. What am I missing here ??? Thanks for all your great videos.

great job man

awesome!!!

I learnt something! Great video, thanks :-)

No it would be different because light behaves in a different state in countries that do not use feet. Does this make sense?