What is the Purpose of ISO in Photography? – Easy Explanation
ISO is one of the three key settings in photography, but what does it actually do? In this easy explanation, I’ll break down the purpose of ISO, how it controls brightness, and its impact on image quality. You’ll also learn how increasing ISO can introduce noise and when to use high or low ISO settings for the best results. Whether you’re a beginner or need a refresher, this quick guide will make ISO easy to understand. Let’s get started!
This video is from our Digital Photography 101 Course.
Video Summary:
This tutorial covers the ISO setting, which controls the camera sensor’s sensitivity to light. Increasing the ISO makes the sensor artificially amplify incoming light, resulting in a brighter exposure. Conversely, lowering the ISO makes the image darker. The key trade-off is that higher ISO values introduce digital noise (grain) into the photo, while lower ISO values produce clean, sharp images. The video demonstrates this through a practical exercise, comparing a clean shot at ISO 100 with a noisy shot at ISO 6400.
Timestamps:
0:06 – Introduces ISO as a setting that controls exposure (brightness/darkness) but is less creatively driven than shutter speed or aperture.
0:57 – Explains the basic principle: Increasing ISO tells the sensor to amplify the incoming light, making the image brighter. Decreasing ISO makes the image darker.
3:11 – Introduces the major downside: Artificially boosting light with high ISO creates digital noise (grain) in the image.
4:04 – Live demonstration: Shows how adjusting the ISO value in real-time directly affects the brightness of the live view image.
4:50 – Clarifies that selecting the exact ISO value will be covered in a later video about balancing all three settings together.
5:26 – Practical Exercise: Takes two comparison shots.
* 5:32 – Takes a shot at ISO 100 (low noise).
* 5:51 – Takes a shot at ISO 6400 (high noise).
6:27 – Compares the results:
* ISO 6400 Shot: When zoomed in, the image is visibly full of noise and grain.
* ISO 100 Shot: The image remains clean and sharp, suitable for large prints.
