In just 5 minutes you’ve provide precise information while others seem to make it more complicated using more time. Encouraging to repeat the experiment is the best advice of all. Kudos and Thank you!
Back in 1972 I assisted top wedding photographer Monte Zucker who introduced using on camera fill + off camera key lighting to shooting on the move at weddings receptions with exposure and ratio controlled via distances in very clever and easy to execute way based on inverse square. We would systematically shoot from 16, 11, 8 and 5.6 feet, easy to remember because they are the same as f/stop numbers and like f/stops change intensity of the light by one f/stop. A flash was mounted on a bracket so the flash hit the faces at a downward angle creating nearly shadowless “butterfly” modeling as foundational fill do lift the shadows. The off camera flash was placed on a rolling IV pole that had modified to hold the flash which had a compact heavy base which could be moved around with one hand. A key light one stop brighter was needed to ideally expose the highlights so starting from a position of 16ft with camera fill the off camera flash would be place at 11ft with aperture set to f/5.6. Moving in to 11ft the Key light moved to 8ft and aperture was closed to f/8. Shooting from 8ft the off camera key would move in to 5.6ft and aperture closed to f/11. From 5.6ft the off camera flash moved to 4ft and aperture changed to f/16. That might sound complicated but after doing it a few times it became second nature. Because Fill was always over the camera all that needed to be done is move the off camera light and change aperture when changing shooting distance and crop. I still use it fifty years later when shooting with speedlights mounting on the fill on a Strobroframe camera-flip bracket with every digital camera I’ve owned since 2000.
So I just did the CPP exam today and as I was getting ready I had this strange urge to look this up again, although I have a pretty good understanding of it. Well the way you explain this easily helped me with 5 questions haha! Thanks buddy! I passed!
Worth noting the inverse square law is only valid if the light can be regarded as point source relative to the subject, and is sort of diverging. In close proximity of a huge softbox, it would not apply, nor for a bundled beam like a laser (beware of your sensors!), or to some degree when using a a tele reflector and a grid, or a snoot.
Re: Inverse Sq. Law: LIGHT is light is light.....so are the physics of photons. I don't agree w/ your soft box analogy at all; grab your hand meter and take a reading at 6ft. Take another reading at 12ft. YOU are telling me that YOU get the SAME exposure reading? Hahahahaha!!!!!! Yikes.
@@tommynikon2283 Not at all: at 6 feet distance, a 3 feet softbox can be regarded more or less as a point source. But when I shoot video and use a backlit 2x2m diffusion close to the talent (say 1m to 1,5m away), things are different. Intensity will still be reduced with distance, but not as strong as the inverse square law would suggest. Or put that 3 feet softbox 1 vs 2 feet away from a subject, for example for a head shot. I'm not saying the exposure stays constant, but fall off would be less drastic, close to linear with the distance.
I’m not sure what you’re trying to say but if you’re adding diffusion or changing modifiers that’s not apples to apples. We need to know your meter readings with the same source at different distances.
@@JohnGress Hi John, thanks for the great sample images and tutorial. I'm just trying to say that if the light source is big compared to the subject distance, the fall off is much slower than the inverse square law would suggest. In above sample the back lit diffusion would be the effective, huge light source.
guarantee, 90% of "people with camera's" still don't understand the concept 😂.... not your explanation, just that most people who get into photography have zero interest in the physics behind what is going on. The concept is not so much about double distance, quarter light (I still have people argue with me its half 🤦♂🤦♂) but more about brightness ratio decreasing as the light is moved further away.
In just 5 minutes you’ve provide precise information while others seem to make it more complicated using more time. Encouraging to repeat the experiment is the best advice of all. Kudos and Thank you!
Thanks! I hope it was helpful!
Thank you John. Very helpful video
Glad it was helpful!
Back in 1972 I assisted top wedding photographer Monte Zucker who introduced using on camera fill + off camera key lighting to shooting on the move at weddings receptions with exposure and ratio controlled via distances in very clever and easy to execute way based on inverse square.
We would systematically shoot from 16, 11, 8 and 5.6 feet, easy to remember because they are the same as f/stop numbers and like f/stops change intensity of the light by one f/stop. A flash was mounted on a bracket so the flash hit the faces at a downward angle creating nearly shadowless “butterfly” modeling as foundational fill do lift the shadows. The off camera flash was placed on a rolling IV pole that had modified to hold the flash which had a compact heavy base which could be moved around with one hand. A key light one stop brighter was needed to ideally expose the highlights so starting from a position of 16ft with camera fill the off camera flash would be place at 11ft with aperture set to f/5.6. Moving in to 11ft the Key light moved to 8ft and aperture was closed to f/8. Shooting from 8ft the off camera key would move in to 5.6ft and aperture closed to f/11. From 5.6ft the off camera flash moved to 4ft and aperture changed to f/16.
That might sound complicated but after doing it a few times it became second nature. Because Fill was always over the camera all that needed to be done is move the off camera light and change aperture when changing shooting distance and crop. I still use it fifty years later when shooting with speedlights mounting on the fill on a Strobroframe camera-flip bracket with every digital camera I’ve owned since 2000.
Thanks for sharing this time tested practical example! If it works... it works!
One of the best, if not the best explanation of the inverse square law ever…and I have watched quite a few 😂
Wow! Thank you so much!
Such an excellent educator. Clear, concise and thorough. Answers considerations and questions I have without me having to ask them. Thank you!
Wow, thank you!
Fantastic video yet again John
Thank you so much! I hope it helps!
This was sooooooo goooooood and helpful! One of the best explanations ever.
That’s great to hear! Thank you so much!
learning or relearning basic concepts always works
I hope it helps!
Such a great teacher! I look forward to taking your class if you ever return to California
Thanks! I will be there in the spring!
Wow, thanks alot sir🔥🔥🔥
Thank you ao much!
So I just did the CPP exam today and as I was getting ready I had this strange urge to look this up again, although I have a pretty good understanding of it. Well the way you explain this easily helped me with 5 questions haha! Thanks buddy! I passed!
That’s great! Anything else I should cover 😊 congrats!
Great stuff, also please note that law dose not work same way on fresnel light, 👍🏻
Спасибо!
Worth noting the inverse square law is only valid if the light can be regarded as point source relative to the subject, and is sort of diverging. In close proximity of a huge softbox, it would not apply, nor for a bundled beam like a laser (beware of your sensors!), or to some degree when using a a tele reflector and a grid, or a snoot.
Re: Inverse Sq. Law: LIGHT is light is light.....so are the physics of photons. I don't agree w/ your soft box analogy at all; grab your hand meter and take a reading at 6ft. Take another reading at 12ft. YOU are telling me that YOU get the SAME exposure reading? Hahahahaha!!!!!! Yikes.
@@tommynikon2283 Not at all: at 6 feet distance, a 3 feet softbox can be regarded more or less as a point source. But when I shoot video and use a backlit 2x2m diffusion close to the talent (say 1m to 1,5m away), things are different. Intensity will still be reduced with distance, but not as strong as the inverse square law would suggest. Or put that 3 feet softbox 1 vs 2 feet away from a subject, for example for a head shot. I'm not saying the exposure stays constant, but fall off would be less drastic, close to linear with the distance.
I’m not sure what you’re trying to say but if you’re adding diffusion or changing modifiers that’s not apples to apples. We need to know your meter readings with the same source at different distances.
@@JohnGress Hi John, thanks for the great sample images and tutorial. I'm just trying to say that if the light source is big compared to the subject distance, the fall off is much slower than the inverse square law would suggest. In above sample the back lit diffusion would be the effective, huge light source.
guarantee, 90% of "people with camera's" still don't understand the concept 😂.... not your explanation, just that most people who get into photography have zero interest in the physics behind what is going on. The concept is not so much about double distance, quarter light (I still have people argue with me its half 🤦♂🤦♂) but more about brightness ratio decreasing as the light is moved further away.