ISO | How Sensitive is Your Sensor?

This is part 2 of a 5 part series on the Exposure Triangle.

Understanding Exposure Triangle | Cheese Photography 101Three variables control the amount of light that reaches your camera sensor. Represented in the exposure triangle, these variables work together and affect the quality and composition of your image.

Understanding and learning to control your exposure through ISO, Shutter Speed and Aperture is the foundation of photography. Consciously controlling your exposure opens up a world of creative possibility.

Today, we’re exploring ISO.

ISO controls the sensitivity of your camera’s sensor to light. If you are familiar with old-school filmstock, this equates to the film speed. Low ISO, in the 100 – 400 range, results in the cleanest image with the least amount of grain. Higher ISO, 800 – 1000+ are more sensitive to light, allowing you to shoot in lower levels of light but result in increasing level of grain.ISO & Grain | Cheese Photography 101
Notice how both images look comparable in the balance of light and dark. The high ISO on the right allowed for an incredibly quick shutter speed compared to the image on the left. The downside is that it’s less crisp – more grain – when you zoom in.

Lesson: Keep your ISO Low for Best Quality

On digital images, grain may not be noticable. On large prints, it will be much more noticeable.

Some photographers even add grain as a stylistic choice, and you may like the look. If not, you can reduce grain in editing software, so never let low light prevent you from getting a shot.

Alternatives to higher ISO:

  • Use a tripod to capture images at slower shutter speed
  • Use a wide aperture and fast lens (f/2.8 or lower)
  • Use a reflector or get closer to your light source
  • Add artificial light

Bottom Line: ISO is there to help you in low light situations. Higher ISO should be avoided for highest image quality. Use ISO as a tool in conjuction with the other aspects of the Exposure Triangle to achieve your perfect shot.