ISO does not create noise

Summary

In this video, the creator debunks common misconceptions about ISO, exposure, and noise in low-light filming. It explains that ISO doesn’t directly affect exposure, and higher ISO simply amplifies existing noise. The video introduces the concept of dual-native ISO and how it helps reduce noise for cleaner images. It emphasizes proper exposure techniques, such as exposing to the right, and acknowledges that low-light scenes don’t need to be well-exposed. The video encourages videographers to understand their camera settings and light levels to achieve the best image quality without overwhelming noise.

Takeaways

• 😀 ISO does not directly affect exposure. It amplifies the signal after light hits the sensor, which is why it increases noise in low-light situations.
• 😀 Increasing ISO does not add more noise; it makes the existing noise more visible by amplifying the signal already captured by the sensor.
• 😀 Dual native ISO cameras have two optimal ISO settings, allowing you to capture cleaner images without digital noise boosting.
• 😀 In low-light situations, the noise floor is more noticeable due to the lack of light hitting the sensor, and boosting ISO just amplifies this noise.
• 😀 Noise is a natural byproduct of electronic systems and manifests as electromagnetic radiation. The signal's clarity determines how much noise is visible.
• 😀 Filmmakers use more light than you think in low-light scenes, often masking the actual lighting setup to make it appear darker or more practical.
• 😀 Low-light footage should not always aim to be bright; it’s okay for the scene to remain dark to avoid introducing excess noise.
• 😀 The key to getting clean footage is to avoid boosting ISO too much in post-production, and instead, expose for brightness without overexposing highlights.
• 😀 Exposing to the right (ETTR) on the histogram can reduce noise but risks highlight clipping. It’s important to balance exposure for cleaner images.
• 😀 For the cleanest images in low-light conditions, use your camera’s native ISO settings. Avoid boosting ISO above those settings to prevent excessive noise.

Q & A

Why does low light footage often turn out noisy, even with an expensive camera?

Low light footage becomes noisy because the ISO amplifies the existing noise from the sensor. Even with a $4,000 camera, increasing ISO to compensate for low light does not add more light to the sensor, it only amplifies the noise that is already there.

What is the misconception about how ISO affects exposure?

The misconception is that ISO affects exposure by adjusting the sensor’s sensitivity to light. In reality, ISO only amplifies the signal after the light hits the sensor and does not directly affect the amount of light hitting the sensor.

How does the radio analogy explain the relationship between light and ISO?

The radio analogy compares the incoming light to a radio signal. If the signal is weak (low light), turning up the volume (increasing ISO) doesn’t improve the signal; it just amplifies the static (noise), which is similar to what happens when you increase ISO in low light conditions.

What is the noise floor and how does it affect image quality?

The noise floor is the baseline level of noise created by the sensor and electronics. The higher the ISO, the more the noise floor is amplified, making the image appear noisier, especially in darker areas of the image where the light is closer to the noise floor.

Why is underexposure problematic when using high ISO in low light?

Underexposure is problematic because it keeps the pixels closer to the noise floor, leading to more noticeable noise when the ISO is increased. Despite the image appearing properly exposed on the camera, it is still underexposed and noisy in post-production.

What does dual native ISO mean, and how does it help reduce noise?

Dual native ISO refers to a camera sensor having two analog circuits that produce two base ISOs without digital amplification. This results in cleaner images at these ISOs, as there is less perceived noise compared to other ISO values.

What happens when you shoot at ISOs between the two native ISO values?

Shooting at ISOs between the two native ISOs is inefficient because the camera compensates with digital boosting, which increases noise. It’s better to stick to the native ISO values for the cleanest image.

How do filmmakers achieve clean low light footage if high ISO creates noise?

Filmmakers often use additional lighting to ensure their scenes are well-lit enough that the camera does not need to boost ISO excessively. They can also lower the exposure in post-production to maintain clean footage without overexposing highlights.

Why do low light scenes in movies often appear darker than they really are?

Low light scenes appear darker because filmmakers use multiple light sources to light the scene while giving the illusion that it is lit by a single practical light. This allows them to control the exposure and avoid excessive noise.

What does 'expose to the right' mean, and how does it affect noise and highlight detail?

'Expose to the right' means adjusting your exposure to brighten the image without clipping highlights. This technique reduces noise by moving the image further away from the noise floor, but it risks losing highlight detail if overdone.