What is ISO — Camera ISO and the Exposure Triangle Explained [Ep 2]

Summary

This video breaks down ISO within the exposure triangle—explaining how ISO controls a digital sensor’s light sensitivity while aperture and shutter speed control light physically. It contrasts film speed and organic film grain with digital noise, stressing that higher ISO brightens shots but increases noise. Practical tips include setting aperture and shutter first, then adjusting ISO, and aiming for a camera’s native ISO (e.g., ARRI Alexa Mini LF at 800) for best dynamic range and minimal noise. Cinematographers like Roger Deakins and Brandon Trost are used as examples of creative ISO choices. A free ebook and a follow-up on shutter speed are offered.

Takeaways

• 💡 ISO refers to the sensitivity of a camera’s sensor to light, originally derived from film speed ratings in traditional photography.
• 🎥 The term ISO comes from the Greek word 'isos' meaning 'equal,' and it is standardized by the International Organization for Standardization.
• 🔺 ISO is one of the three key components of the exposure triangle, alongside aperture and shutter speed.
• 📸 A lower ISO value makes the sensor less sensitive to light, resulting in a darker image, while a higher ISO increases brightness.
• 🌙 In low-light situations, cinematographers often raise ISO to achieve proper exposure without changing aperture or shutter speed.
• 🎬 Increasing ISO can introduce digital noise or grain, which can reduce image quality if pushed too high.
• 🧠 Every camera has a native ISO, which provides the best balance of brightness, color, and minimal noise; shooting near this value yields optimal results.
• 🌈 The dynamic range of a camera defines how well it captures details in both dark and bright areas; adjusting ISO affects this range.
• 🎞️ Film grain and digital noise are not the same—film grain results from chemical processes in film, while noise is a digital artifact from high ISO.
• 🎨 Some filmmakers creatively use high ISO and noise to mimic the texture of film grain for a stylized, analog look.
• 📚 Understanding ISO, along with aperture and shutter speed, is essential for controlling light and crafting cinematic visuals effectively.

Q & A

What is ISO in cinematography?

ISO refers to the sensitivity of a camera’s sensor to light. A lower ISO value makes the sensor less sensitive and produces darker images, while a higher ISO increases sensitivity and brightness.

Where does the term ISO come from?

The term ISO comes from the Greek word 'isos', meaning equal. It’s also an acronym for the International Organization for Standardization, which sets various international standards, including for camera sensitivity.

How does ISO differ from aperture and shutter speed in the exposure triangle?

Aperture and shutter speed physically control how much light enters the camera, while ISO determines how sensitive the camera sensor is to that light. All three work together to achieve proper exposure.

What happens when you increase the ISO setting on a digital camera?

Increasing ISO makes the sensor more sensitive to light, which brightens the image but also introduces digital noise or grain, reducing overall image quality if pushed too far.

Why might a cinematographer choose a higher ISO in low light situations?

In low light conditions, a higher ISO allows the camera to capture more light without needing to open the aperture or slow the shutter speed, which helps maintain desired depth of field or motion characteristics.

What is the native ISO of a camera and why is it important?

The native ISO is the baseline sensitivity setting where a camera performs best, capturing maximum dynamic range with minimal noise. Shooting close to the native ISO produces cleaner, more detailed images.

How did cinematographer Roger Deakins use ISO in the film '1917'?

Roger Deakins used a high ISO setting (around 1600) on the ARRI Alexa Mini LF camera to shoot in low light with minimal artificial lighting, allowing him to maintain deep focus and realistic visuals.

What is the difference between film grain and digital noise?

Film grain is a natural texture produced during the chemical film development process, giving an organic, moving quality to images. Digital noise, on the other hand, is an electronic artifact caused by high ISO sensitivity in digital sensors.

How did cinematographer Brandon Trost use ISO creatively in 'The Disaster Artist'?

Brandon Trost intentionally shot at high ISO values and added grain in post-production to create a textured, analog look reminiscent of film, adding character and visual interest to the movie.

How does dynamic range relate to ISO adjustments?

Dynamic range measures how much detail a camera can capture between the darkest and brightest areas. Changing ISO can shift this range, often sacrificing detail in either highlights or shadows depending on the direction of adjustment.

What general rule should filmmakers follow to minimize noise in their shots?

Filmmakers should aim to shoot as close as possible to the camera’s native ISO and avoid pushing ISO too high, as this helps maintain a clean image with minimal digital noise.

Why might filmmakers intentionally introduce noise or grain into their footage?

Some filmmakers use grain or noise for artistic purposes, adding texture and a tactile quality to their images to evoke a nostalgic or filmic aesthetic.