♪ ♪
Light is responsible for everything we see on the big screen.
Awe.
Spectacle.
Magic.
Just as often as cinematographer use light to tell a story,
they also use darkness.
To capture the range of human emotions through light and darkness,
it is fundamental to understand the three components of the exposure triangle.
Aperture, Shutter Speed, and today's topic ISO.
This is "What Is ISO?"
To stay in the loop for more filmmaking techniques,
subscribe and click the bell.
So how does ISO work?
Back when filmmakers shot exclusively on film
different film stocks had different speeds
or sensitivities to light.
The film sensitivity is known as ISO.
The term comes from the Greek "Isos",
meaning equal
and is defined by the international organization for standardization (ISO).
ISO sets various international standards
for everything from country codes to medical devices.
In today's digital camera technology
ISO is used for the sensitivity of a camera's sensor,
rather than film.
Aperture and shutter speed, both physically control
the amount of light let into the camera.
In our previous episode on the exposure triangle,
we discussed how aperture works,
like the pupil of an eye.
It closes to let in less light.
Or opens to let in more light.
And the ISO controls how sensitive the camera's sensor is
to the light that hits it.
Lastly, the shutter speed controls, how long light will hit the sensor.
We'll cover this in our next episode.
Now, a lower ISO value makes the sensor less sensitive to light
making the image darker.
A higher ISO value makes the sensor more sensitive to light
making the image brighter.
When determining the exposure of a shot
it is most common to adjust your ISO
after your aperture.
And shutter speed are set.
So why would a cinematographer change their ISO?
Let's look at a couple of different scenarios
starting with low light situations.
The film "1917" spans various long takes
to create an immersive 360-degree experience.
This meant that cinematographer, Roger Deakins
had to light many of the darker scenes
with practical lights, visible on screen...
...while still retaining a deep focus.
"- Look at this.
He's massive."
In other words, Deakins had to contend with less lighting
and a closed aperture.
Remember, to get a larger depth of field,
you want to close your aperture as much as possible,
but this means less light will enter your sensor.
So to pull this off, he needed a camera that could handle
extremely low light situations.
The ARRI Alexa Mini LF.
" - Very thankful for this camera. Thank you very much.
Certainly served our purpose very well.
The LF I could rate it at 1600.
Because there's all the night scenes in the interiors.
There's quite a lot of footage at night in those little bunkers."
Because of this high ISO
Deakins could light minimally
while closing his aperture
to achieve a larger depth of field.
However, there is a side effect of increasing your ISO
that every cinematographer should be aware of.
Noise.
Increasing your ISO
may help brighten up your shot,
but there is a catch.
If your ISO is too high, your camera sensor will become too sensitive
and it will create noise and grain.
Take this low light shot for example,
this image is clearly underexposed.
To properly expose the shot
without compromising your aperture or shutter speed
let's try increasing our ISO.
Notice how increasing the ISO value
brightens up our shot,
but also produces more noise.
So how do you minimize noise?
Get to know your camera.
Every camera is a little different
so understand its particular settings
like its "Dynamic Range" and "Native ISO".
The dynamic range measures the limits
of how dark and light an image can be
without losing detail.
So a larger dynamic range
results in more detail and color range.
Adjusting the ISO in either direction
moves that range
sacrificing either the highs or lows in the process.
As a general rule, to shoot an image with less noise
and greater range of color,
you'll want to shoot as close to as possible
to what is known as a native ISO.
Every digital camera has a native ISO
specific to that camera.
For instance, the ARRI Alexa Mini's native ISO is 800.
Although many cinematographers strive for polished image,
some filmmakers take advantage of green and noise
because the texture can bring a unique quality to a shot.
"- Film Photography is a chemical miracle.
It always looks different. It always looks real.
There's grain. Number one.
And the grain is always moving, it's swimming,
which means that even in a still life of,
let's say a flower
that flowers alive even though it's not moving
because the film itself, the image is alive.
And that's the difference."
Spielberg is referring to film grain.
Not digital noise.
"- What are you doing?
- I was filming this dead bird. - Why?
- Because it's beautiful."
Remember, there's a clear difference between the two.
♪ ♪
An image captured on a film strip
produces film grain
during the chemical bath it takes when it's been converted.
"- You never quite know what you're going to get after the film takes a bath
and exposes the positive from the negative."
This is not to be mistaken for noise,
which is when ISO is pushed too far on a digital camera
producing less desirable artifacts.
However, some filmmakers intentionally use a high ISO value
to create noise, to create an analog-style
reminiscent of film green.
Cinematographer Brandon Trost uses this quality in the film "The Disaster Artist".
"- Guys, this is real Hollywood movie.
- Everyone set? - Yeah.
- Ready. And, uh, action."
Trost shot the movie at 3,200 ISO
and added additional green in post, purely for style.
"- I think I don't like things that look super nice.
It gives you a variety, you know stuff that's interesting
texture stuff that you can like reach out and touch
and that's sort of what I'm always after a little bit."
Whether your cinematography style utilizes low
or native ISO values for a polished look.
Or you're looking to use higher ISO values to produce noise stylistically.
"- Ha-ha-ha! What a story, Mark!
- Cut!"
Understanding ISO is crucial
in achieving the shot you envision.
And to fully understand ISO,
you must learn how it works with aperture and shutter speed
within the exposure triangle.
In the description,
you'll find a link to download a free ebook on the exposure triangle.
And how each of the three settings work in combination.
Did any shots come to mind as we covered ISO?
Share your favorites in the comments below.
In the next episode, we'll explore shutter speed
and how it's used to control light and motion.
We've got new content every week.
Click "Subscribe" and ring the bell to find out what we do next.
We'll see you in the next one.
♪ ♪