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This is the f-stop scale.
One method that photographers use to control the visual qualities of their
images by controlling stops of light.
I don't think reciting the f-stop scale from memory is required
knowledge to be a great photographer.
It's really not even an impressive party trick.
However understanding light in stops allows you to identify limitations, work
faster and repeat successful techniques.
In today's video, I'm going to explain a stop of light
in every facet of photography.
Now, properties of light are difficult to understand at first, because it's
not like you can just grab a hold of light to make it more visual.
I'm going to strip away all the color and illustrate the properties of light
Using water.
A stop is a measurement of a relative doubling or having of light.
To better understand this.
Let's imagine that water is light. Here
I have three glasses in the left glass.
I put one spoon of light in the middle glass.
I put two spoons of light.
The middle glass has double the light as the left glass, which means the
middle glass has one more stop of light relative to the left glass.
If I want the right glass to have one more stop of light than the middle glass
I have to put in four spoons of light.
With four spoons of light, the right glass has two stops, more light than
the left glass, since it doubles twice.
Shutter speed.
Shutter speed is the amount of time.
An image sensor is exposed to light.
A shutter speed of 1/30th of a second is double the time of 1/60th of a second.
So 1/30th of a second lets in one stop of light more than 1/60th of a second.
Opening the sink faucet is like opening the shutter.
It begins the process of filling the glass with water, just like a
shutter opening begins the process of exposing the sensor to light.
The longer we leave the faucet open, the more water fills the glass
aperture aperture refers to the round opening in a lens that allows
light to pass through. F-stop numbers
refer to the ratio of that opening.
As the f-stop number increases, the size of the opening gets smaller.
The familiar numbers of F/2 F/2.8 F/4 4/5.6 and F/8
are all full stop increments.
Increasing your f-stop number from F/5.6 to F/8 means you reduce
the area of the opening by half reducing the amount of light that
makes it to the sensor by one stop.
I have the same control with that faucet.
As I open it, more water flows out, faster, filling up the glass faster,
the larger, the opening for water to go through the less time is needed for the
glass to fill just like on a camera.
The wider the aperture is to let light in the faster your shutter
speed can be to compensate.
ISO represents how sensitive the image sensor is to light.
When you increase a camera's ISO from 100 to 200, it becomes twice as sensitive
to light. With everything else equal and image at ISO 200 will be one stop
brighter than an image at ISO 100.
We can increase the sensitivity of the glass of water by adding ice.
The more ice that is added, the less water it takes to fill
the glass. exposure triangle.
The relationship between shutter speed, ISO and aperture is
called the exposure triangle.
Each control allows photographers to modify the brightness of an image.
And each has its own visual tradeoffs.
Ultimately photographers can approach the same situation and create an
image of the same brightness, but use completely different settings.
Back to the sink.
Let's say a glass filled to the top represents a properly exposed photo.
We can fill it a number of ways.
We can use a narrow aperture and low ISO and have a very long shutter speed.
Or we can use a wide aperture high ISO and have a very short shutter speed.
If the combination of camera settings lets in too much light, the result
is an overexposed image, which means the sensor loses details.
If the combination of camera settings doesn't let in enough light, the
result is an underexposed image.
Meaning the sensor never had enough light to capture all the details.
Flash power, everything up to this point is true of any constant light
source, whether it be daylight, incandescent lighting in a room
or light from an led panel.
But another powerful tool for photographers is flash.
If we're still trying to fill that glass of water and the
faucet represents constant light.
Flash Is like having a spare cup of light ready to dump into your sensor glass
at any moment, flash can be controlled by turning its output up or down.
And this is normally represented in fractions.
Although sometimes it's represented with integers for fractions, one over
one means the flash is at full power.
One over two is half of that peak power and you guessed it.
One stop of light, less than full power.
This goes down to some tiny levels with the minimum power of some flashes reaching
1/256 or less fleshes also vary in their size and max output potential.
So larger, more powerful flashes are like having a larger glass of water.
Light distance.
Another thing that affects light intensity is distance.
Whether yeah, using a flash or a constant light source distance
to the subject affects the
Intensity of light that hits that subject.
Let's say you take a light that was four feet away from a subject and move it
to only two feet away from a subject.
Since a light has half the distance of travel, the light
will be 4 times as intense.
This is known as the inverse square law.
The same principle can be seen with water as you get closer to the water source.
The intensity of it is increased light modifiers.
The type of light modifier used on a light source affects the
intensity of light. A light modifier
Designed to concentrate.
Light will have greater intensity than a modifier designed to spread light up.
There's no perfect math behind this.
As things such as material reflectiveness, strength of diffusion size shape,
all affect the intensity of light ND filters, gels, and diffusion.
Neutral density or ND filters are designed to reduce the light intensity.
These exist to be put on camera lenses, camera sensors,
or even in front of a flash.
This is like having material between the water source and the
glass, as it reduces the amount of water that goes through.
The more dense the material, the less water that makes it through, which
is the same case for ND filters.
The strength of an ND filter can be represented in stops like a 10 stop ND
filter and others use a filter factor number such as ND1000, the filter
factor number of ND 1000 representing light intensity reduction of one,
1000, which is the same as 10 stops.
To various degrees, ND filters, color gels, and diffusion material.
We'll reduce the amount of light that passes through them.
And this is normally represented on the product so that you can keep track of it.
Post-processing so while you already have a ton to consider with controlling
the intensity of light, it doesn't completely stop at capturing a photo.
In post-production, you can simulate a change in light intensity by using
things like the exposure slider in Lightroom, adding plus one on
this exposure slider increases the brightness by you guessed it.
One stop.
It's important to know that this is a digital process that simulates
capturing more light, and it definitely has its limitations.
Capturing light appropriately with your camera is always
the best starting process.
All these tools from the camera controls, flash power, flash distance, flash
modifiers, and post-processing are what makes the creative process of photography.
So nuanced and so interesting.
It's also what allows billions of photos to be captured every single day.
Without everything looking the same.
So I encourage you to make sure you are using all the tools
available to take control of light.
If you're new to flash photography, I've made a playlist dedicated to
taking control of off camera flash.
It's linked in the description below.
I hope you enjoyed this video.
If you did make sure to hit that like button for me and share it
with anyone or any groups that you think will benefit from it.
Comment below if you have any questions and subscribe.
If you'd like to see more of my videos until next time.
Keep on shooting.