Understanding ISO in Cinematography

Introduction

• Light and darkness are crucial in cinematography for emotion portrayal.
• Importance of understanding the exposure triangle: Aperture, Shutter Speed, and ISO.

What is ISO?

• ISO Origin: Term comes from Greek "isos" meaning equal.
• Defined by the International Organization for Standardization.
• Historically referred to film sensitivity; now applies to digital camera sensor sensitivity.

ISO in Digital Cameras

• Function: ISO controls the sensitivity of the camera sensor to light.
• Comparison with Aperture & Shutter Speed:
  • Aperture: Controls light entry, similar to an eye's pupil.
  • Shutter Speed: Controls duration of light exposure.
• Affects brightness of the image:
  • Lower ISO = Less sensitivity = Darker image.
  • Higher ISO = More sensitivity = Brighter image.

Adjusting ISO

• Typically adjusted after setting aperture and shutter speed.

Cinematographer Considerations for ISO

• Low Light Situations:
  • Example: Film "1917" by Roger Deakins.
  • Used Arri Alexa Mini LF with high ISO for minimal lighting and deep focus.
• High ISO Drawback: Introduces noise and grain into images.
  • Example: Increases sensitivity but causes undesirable artifacts.

Minimizing Noise

• Know your camera’s dynamic range and native ISO.
• Dynamic Range: Limits of light/dark detail in an image.
• Native ISO: Optimal ISO setting for minimal noise and high detail/color range.
• Example: Arri Alexa Mini’s native ISO is 800.

Noise vs. Film Grain

• Film Grain: From chemical process in film photography; visually different from digital noise.
• Digital Noise: Result of pushing ISO too high on digital cameras.

Using Noise for Style

• Some filmmakers use noise and grain for a unique texture.
  • Example: Brandon Trost in "The Disaster Artist" used high ISO for stylistic effects.

Conclusion

• Understanding ISO, alongside aperture and shutter speed, is crucial for achieving desired shots.
• Links to resources and ebooks on the exposure triangle.

Next Steps

• Upcoming episode on shutter speed.
• Encourage engagement and subscription for more content.