Understanding Light in Photography. Part One: Intensity

Summary

This video script introduces a new series of lighting tutorials, emphasizing the importance of understanding light properties before using devices like flashes. The host covers the four key qualities of light: intensity, color, direction, and quality. Demonstrations using a desk lamp and an LED light illustrate how light intensity affects exposure, and the inverse square law is explained to show how distance impacts light intensity. Practical examples and a quiz are provided to help viewers grasp these concepts, with the goal of improving their photography skills.

Takeaways

• 📚 The video is part of a new series on lighting tutorials, focusing initially on understanding the properties of light before using specific devices like flashes.
• 🔆 The four main qualities of light discussed are intensity, color, direction, and quality.
• 💡 Intensity of light refers to how much light is hitting the subject and can be adjusted by the power of the light source or the distance between the light and the subject.
• 🔄 Understanding 'stops' in photography is crucial, as they measure changes in light intensity and camera settings, doubling or halving the light with each stop.
• 🔦 Different light sources have different power levels, and 'full power' is relative to the specific light being used.
• 📐 The inverse square law explains how light intensity changes with the distance from the light source, with exposure changing in stops as the distance is halved.
• 📷 Practical application of the inverse square law includes adjusting camera settings or light power when changing the distance to subjects or including more subjects in the frame.
• 👥 When lighting a group, the inverse square law can affect exposure unevenly, with those closer to the light receiving more light, causing a need for adjustments.
• 🌟 Fall-off describes how light decreases rapidly when the light source is close, affecting the evenness of exposure in group shots.
• 🔄 To evenly expose a group, moving the light source further away and adjusting its power can help, as the light becomes more even as it spreads out.
• 🎥 The presenter emphasizes the importance of understanding these lighting principles for practical photography scenarios, such as parties or group photos.

Q & A

What is the main focus of the video series introduced in the script?

The main focus of the video series is to teach lighting tutorials, starting with the understanding of the properties of light before moving on to the use of specific lighting devices like flashes.

What are the four qualities of light that the video series will cover?

The four qualities of light to be covered are intensity, color, direction, and quality of light.

Why is it important to understand the properties of light before using a flash?

Understanding the properties of light is important because it provides a foundational knowledge that helps in effectively using a flash and achieving the desired lighting effects in photography.

What does the term 'intensity of light' refer to in the context of the video?

The intensity of light refers to the amount of light hitting the subject, which can be adjusted by the power of the light source or the distance between the light source and the subject.

How are changes in light intensity measured in photography?

Changes in light intensity are measured in 'stops'. Doubling or halving the light is considered a one-stop change.

What is the inverse square law and how does it relate to photography?

The inverse square law states that the intensity of light is inversely proportional to the square of the distance from the light source. In photography, it helps in understanding how changing the distance between the light source and the subject affects the exposure.

How does the distance between the light source and the subject affect the exposure in photography?

The closer the light source is to the subject, the brighter the subject will be. Conversely, moving the light source further away will result in a dimmer exposure. This relationship is governed by the inverse square law.

What is 'fall-off' in the context of lighting for photography?

Fall-off refers to the rapid decrease in light intensity as the distance from the light source increases, resulting in a less even exposure, especially noticeable when the light source is very close to the subject.

How can one evenly expose a group of people in a photograph using lighting?

To evenly expose a group, one can move the light source further back and adjust its height as needed, or adjust the flash power and camera settings to compensate for the light fall-off.

What is the practical application of understanding the inverse square law when taking a group photo at a party?

Understanding the inverse square law allows a photographer to adjust their lighting and camera settings appropriately when the number of subjects in the frame changes, ensuring even exposure for all subjects regardless of their distance from the light source.

How can changing the camera settings help maintain the same exposure when the light source is moved further away?

By adjusting settings such as ISO or aperture, a photographer can compensate for the reduced light intensity when the light source is moved further away, thus maintaining the same exposure level.

Outlines

00:00

📚 Introduction to Lighting Tutorials

The video script introduces a new series focused on lighting tutorials. Initially, the plan was to teach the use of a flash, but the creator realized that understanding the fundamentals of light is crucial before delving into specific devices. The series will cover the four main qualities of light: intensity, color, direction, and quality. The host uses a desk lamp and an LED light to demonstrate the principles of light, starting with intensity. The concept of 'stops' is introduced to explain how changes in light intensity are measured, and the importance of considering the unique characteristics of different light sources is highlighted. The inverse square law is briefly mentioned as a key principle that affects light intensity based on the distance between the light source and the subject.

05:02

🔍 Understanding Light Intensity and the Inverse Square Law

This paragraph delves deeper into the concept of light intensity, explaining how it can be adjusted by changing the power of the light source or the distance between the light source and the subject. The inverse square law is explored in detail, demonstrating how the intensity of light changes with the square of the distance from the source. Practical examples are given, such as adjusting exposure settings when photographing a group of people at varying distances from the light source. The paragraph also includes a quiz to test the viewer's understanding of light intensity adjustments and the application of the inverse square law in real-world photography scenarios.

10:03

👥 Applying the Inverse Square Law to Group Photography

The final paragraph discusses the application of the inverse square law in group photography, illustrating how light fall-off can lead to uneven exposure among subjects at different distances from the light source. Techniques to achieve even lighting for a group are presented, such as moving the light source further away and adjusting its angle. The paragraph also addresses how the inverse square law affects background exposure and how photographers can manipulate this principle to balance the exposure between subjects and their surroundings. The host invites feedback and questions, emphasizing the channel's mission to educate and assist viewers in mastering lighting techniques.

Keywords

💡Lighting Tutorials

Lighting tutorials refer to instructional content designed to teach the techniques and principles of using light in photography or videography. In the video, the host introduces a new series focused on lighting, emphasizing the importance of understanding light properties before delving into specific devices like flashes.

💡Intensity of Light

Intensity of light is a measure of the amount of light that hits a subject. It is a fundamental concept in photography and is crucial for achieving the desired exposure. The script explains how adjusting the power of a flash or moving the light source closer to or further from the subject can alter the light intensity, with examples such as changing from full power to half or quarter power.

💡Color of Light

The color of light pertains to the temperature and hue of the light source, which can affect the mood and tone of a photograph. Although not deeply explored in the provided transcript, it is mentioned as one of the four qualities of light that will be covered in the series, indicating its importance in lighting tutorials.

💡Direction of Light

Direction of light refers to the angle or position from which light originates and strikes a subject. While not explicitly detailed in the transcript, it is listed as a key quality that influences how light interacts with a subject and contributes to the overall lighting effect in photography.

💡Quality of Light

Quality of light describes the characteristics of light, such as its softness or harshness, which is influenced by factors like the size of the light source and the presence of modifiers. The script mentions this as one of the four qualities to be covered, suggesting it plays a significant role in shaping the final appearance of a photograph.

💡Flash

A flash is a device used to provide additional light when the ambient light is insufficient. In the video, the host initially planned to teach how to use a flash but realized that understanding the broader principles of light was more important. The term is used to illustrate how changing the power of a flash can adjust the light intensity.

💡LED Light

LED light, as mentioned in the script, is a type of light source that is versatile and can be used for various lighting purposes. The host uses an LED light in the demonstration to show how light properties like intensity can be adjusted, highlighting its role in learning about light dynamics.

💡Inverse Square Law

The inverse square law is a principle that describes how the intensity of light decreases with the square of the distance from the light source. The script explains this concept to help viewers understand how changing the distance between the light source and the subject affects exposure, using examples of moving closer to or further from a window light.

💡Stops

In photography, a stop refers to a unit of measure for the intensity of light, where each stop represents a doubling or halving of light. The script uses the concept of stops to explain how adjusting the power of a light source or camera settings can change the exposure, with examples of moving from one power setting to another on a flash.

💡Fall-off

Fall-off describes the decrease in light intensity as the distance from the light source increases. The script discusses how fall-off occurs more rapidly when the light source is close to the subject, resulting in uneven exposure, especially in group shots, and how adjusting the light's position can lead to a more even distribution of light.

💡Feathering

Feathering in the context of lighting refers to the technique of angling the light source so that the light gradually decreases in intensity as it moves across the subject. The script suggests using feathering to adjust the light on a group of people to ensure even exposure, by pointing the light beyond the last person and adjusting the power accordingly.

Highlights

Introduction to a new series on lighting tutorials.

Emphasis on understanding the properties of light before using devices.

The four qualities of light to be covered: intensity, color, direction, and quality.

Demonstration of light intensity using Captain Rogers and various light sources.

Explanation of how light intensity is measured in stops.

The concept that not all light sources have the same power levels at full, half, or quarter power.

The impact of light distance on intensity and the inverse square law.

Practical application of the inverse square law in adjusting camera settings for different distances.

Demonstration of how light fall-off affects exposure in group shots.

Techniques for evenly exposing a large group by adjusting light distance and power.

The effect of light source distance on background exposure.

How to use the inverse square law to control exposure for both subject and background.

The importance of understanding light properties for better photography outcomes.

Invitation for feedback and questions to enhance learning.

The significance of the inverse square law in practical photography scenarios.

The tutorial's aim to help photographers understand and apply the science of light.

Transcripts

hey guys over here and welcome to a

brand new series called

I don't know what it's called I didn't

call it anything we're gonna do some

lighting tutorials and at first I was

just gonna teach you guys how to use a

flash and I realized that there's so

much more that goes into learning flash

and just learning how to use the device

it's actually more important to learn

how lighting works and the properties of

light first before you start tackling

the little device so in this little

series and if it does well I'll continue

it you got to hit the like button if not

I'm done hey black male so the four

qualities of light that I'm gonna cover

our intensity of light number two we're

gonna talk about the color of light

three direction of light and four the

quality of light so let's I'm here at my

workbench

I got cap I got a little light and we're

gonna just kind of show you more than

tell you how light works let's start

with the intensity of light okay so for

all our lighting demonstrations we're

gonna use Captain Rogers here and I'll

be using my little desk lamp and also

this LED light this bowling we've seen

this guy before I did a video on this

light this is a really great light it

has you can do colors on this light you

can also do the way we're gonna use it

today or gonna use it as an LED but this

is gonna be how we demonstrate how light

works okay so let's start with the first

property of light that we care about in

photography which is the intensity of

light this simply is how much light is

hitting your subject so let's pretend

the LED light here is a flash we could

have maybe a large intensity of light so

maybe the flash is in full power and a

flash if you are using a flash you can

turn the flash down to lower the

intensity of light so kind of like a

dimmer switch

so we'll simulate that here with the LED

maybe the flash goes from full power to

maybe half power

then you do quarter power and etc so

these changes in the intensity in your

light are measured by what are call

stops and it's a photographer you should

always be thinking in stops so a stop

will either double your whoa whoa

comeback cap clear so a stop of light

will either one stop up will double your

light one stop down will have your light

okay so you can say if you're going form

let's say this is 8th power if you go to

let's say quarter power then the light

will double and that's called a stop of

light now coincidentally your camera

also goes by stops so if you go from ISO

let's say four hundred to eight hundred

that also is a stop of light right now

we're only talking about the light and

not so much camera settings so for now

just know that if you switch your light

to each of the powers we're moving them

by stop and we sure stop there now one

thing to know is not all light sources

are built the same this light source

could be maybe a speed light and so if

it's a speed light at full power it

doesn't have let's put let's simulate

that this is full power on the speed

light okay well if you use a mono light

or a studio strobe well that full power

maybe looks like this so not all folk

our they're not all built the same so

just know that full power half power

quarter power is all relative to the

light you're using so the first part of

intensity you can turn your light up or

you can turn your light down the other

thing that affects intensity of the

light is the distance of the light to

your subject

so obviously you move the light closer

it's gonna get brighter on your subject

if you move the light further away from

your subject it's gonna get a little

dimmer now that seems totally obvious

and I know when I was first learning

photography I was like duh but what you

end up learning is that distance to your

subject really changes in a weird way

let me splain so let's pretend that this

light is a window light you can actually

change the amount of exposure on the

person

obviously if you move them closer to the

window hello or if they're further away

from the window but it turns out there's

actually a science to how much the light

goes down and what happens is once you

learn something called the inverse

square law and by the way this is where

most photographers sort of tune out as

soon as they start to learn this science

but it actually is really helpful

because you're gonna know in a second

that if you move your light by a certain

amount you can actually change the

settings on your flash or the saving

settings on your camera to get a good

exposure on your subject

okay the inverse square law super easy

light source subject at twenty if we put

our subject halfway there

okay halfway to the zero you actually

gain two stops of light every time you

have the distance it's two more stops so

it's not one stop and then two stops it

doesn't work that way I have a little

light meter here and so what I'm gonna

do is take a reading and if I take a

reading by tap over here you see it says

this is f/4 that means I would need to

set my camera to f/4 to get him properly

exposed now if I move them halfway

towards the light kind of over here the

10 is halfway and I take a reading if

you notice it says it's f/8 we just went

to stops we went from f/4 to 5.6 to f/8

now if we have the distance again so

we're going halfway which is around this

4 that will be f16 f-16 so we went from

f8 f11 f-16 all right here's a practical

example of when you could use the

inverse square law understanding what's

happening so let's say I'm at a party

and I'm taking pictures of two people um

this far away and I shoot light on the

people and they're perfectly exposed but

all of a sudden 10 people come into the

picture I need to move back with my

light that's set at the same

power okay so if this is properly

exposed and I double my distance how

many more stops do I need to raise my

light to two full stops I was here and I

doubled my distance so that I could get

everyone in the picture and so I can

double I have to actually go up to full

stops of my light that's a lot of light

now if I wanted to keep my flash at the

same power I could change my camera

settings to full stops so for example if

I'm ISO 800 when I took my first picture

well now I can go to ISO 1600 3200 and

you'll get the same exposure to full

stops

okay so let's see if you understood what

we just did here's a little quiz let's

say this exposure right here for cap is

five point six that means he's perfectly

exposed but you want to move the light

closer or move the person closer what is

your new f-stop if this is now properly

exposed and the answer is correct

f11 why because we need to change the

f-stop by two stops if this was five

point six we go f/8 f/11 but here's the

big money question what if you wanted to

shoot at five point six here what do you

need to do where there's two things you

can do you can either change the

settings in your camera or you can

change the light let's start with the

light if you definitely don't want to

shoot at f11 then you need to move your

light how many stops down - that's right

if you want to stay at five point six

you move the person and then you move

your flash power down to stops so on

your flash that would look like this

instead of quarter power we're going to

go to eighth power as one stop and

sixteenth power for the second stop I

just changed my light now if you're at

f11 and you want to change camera

settings well you have to change maybe

your ISO for example if your ISO is too

high like 800 well then - two stops

eight hundred to four hundred four

hundred to two hundred and that'll keep

you at five point six okay for this next

demo I'm going to use these four little

people here so the inverse square law

also comes into play if you have your

light really really really close to a

group of people the person closest to

the light is going to be not only

receiving more light what happens this

is more science of light but what

happens is light falls off very quickly

when the light is close for example this

person is a lot darker than this

exposure here okay how much more

probably two stops one and a half two

two stops now if this same if you keep

the light in the same place and this

group of four is over here well they are

more evenly exposed let me bring up my

pinky because they're getting blocked

but the further you move away from the

light the more even the exposure is over

here okay but light falls off so quickly

where it's crazy bright less bright less

bright and then it sort of evens out

this is called fall-off in this group

shot cap is way overexposed and dr.

strange is in the dark okay so what you

want to do to evenly expose a large

group is you can move your light back of

course you have to raise it as you move

your light back and then they will be

evenly exposed or more evenly exposed as

the light is further back one way around

the inverse square law and getting

around this intensity of light here is

by moving your light and pointing it way

beyond to the last person in your group

if you do that you can feather some of

the light off the person the first

person here raised your power and then

you can sort of try to evenly get enough

light in the back so that's one way you

can evenly light a group instead of

using the you know the inverse square

law is going to mess you up

so if the light is super close to the

person the background is dark if you

move the person away let's raise our

power they are more you know you expose

them properly the background is more

even with them so you can actually

change the exposure on the background

using that inverse square law okay there

you have it guys let me know if that was

helpful or if you have any questions

some of its a little confusing

especially inverse square law if I

missed anything put stuff down below so

people can learn because that's what

this channel is about just helping you

alright I'll see you next time

[Music]