ISO is probably the most misunderstood element in the exposure triangle which also includes shutter speed, and aperture. I’d wager most novice photographers put their cameras on ISO and never think about it again. I was one of those photographers and I couldn’t understand why I wasn’t getting sharp photos. When I look back at old photos, I realize the softness was digital noise caused by an unnecessarily high ISO. So what is ISO and how do you use it?
Understanding ISO In Photography
ISO stands for International Standards Organization which is an international set of standards for a variety of things, most of which aren’t related to photography. No wonder it’s so confusing, right? I wouldn’t worry about acronym or why it’s used, just know that ISO is the camera’s sensitivity to light and controls the image brightness and image quality.
ISO used to be a numerical standard in film photography that described a roll of film’s light sensitivity; depending on the roll’s sensitivity, images would appear darker or brighter. Since digital cameras don’t use film, the modern ISO setting represents how bright the final photo should be. Functionally, it operates the same way as film ISO did, increasing or decreasing the brightness of a photo.
Low ISO numbers represent lower sensitivity to light, producing darker images, while high ISO numbers represent a higher sensitivity to light, producing brighter images. Use higher ISO speeds with caution as higher ISO produces more digital noise which is a grainy look..
For sharp, high-quality photos use the lowest ISO sensitivity possible. Digital noise starts become visible at ISO settings higher than 800, so I recommend trying to stick with ISO’s between 100 and 800. If the photo is too dark your shutter speed and aperture settings instead to increase exposure.
What Is Digital Noise?
Image noise refers to discolored pixels, and a loss of detail that gives photos a grainy look. Every photo has some noise, but too much noise is when the tiny imperfections overwhelming and distracting.
Look at the difference between these two photos. I took the photos under the same conditions, but can you guess which one had the higher ISO?
I used an ISO of 500 for the first photo and an ISO of 8000 for the second photo; the additional noise is especially noticeable in the background area of the second photo because it’s mostly a solid color.
When Should You Use a High ISO?
I recommend a low ISO speed because I don’t prefer digital noise, but noise doesn’t have to be a bad thing. There are creative and practical reason to increase the ISO speed, so just determine the level of noise you are comfortable with and don’t exceed that ISO. In just a moment, I will discuss how to cap your ISO when using Auto ISO. But first, when is noise acceptable?
To Create A Vintage Feel
Image noise was an accepted aspect in vintage photos, as technology improved the clarity of photos improved. Make your photos stand out by intentionally adding grain to age a modern photo.
You Like It
There is a big debate on whether we should hate grain or embrace it. The amount of digital noise is a matter of preference, so if you like the aesthetics and want to use it creatively don’t let the haters tell you not to. In fact, Adobe has acknowledged this preference and has added a grain slider to artificially add noise during editing.
Limited Available Light
If you are in a low light setting or need a faster shutter speed, a higher ISO may be your only option. If having some grain is the alternative to missing the photo entirely, then it’s worth accepting. I shot this image from Carlsbad Caverns with the ISO set at 3200. The caverns are dimly lit and tripods aren’t allowed. There is a limit to how slow handheld shutter speeds can be without causing camera shake, so my only option was to increase the ISO.
To Create A Gloomy Mood
Image noise can contribute to the tone and mood of the image, giving a sense of sadness or a gloomy tone for a rainy day.
Using The Auto ISO Camera Setting
It’s intimidating to think about and manipulate exposure settings with each capture. That’s why Auto ISO is an amazing tool! The camera will determine the best ISO based on the aperture and shutter speed you set. The risk with auto ISO is that the camera could select too high of an ISO and make an otherwise great photo unusable. The easiest solution to this is to cap the auto ISO settings. Determine the highest ISO you can tolerate and set that number as the maximum.
This will force you to think more about your aperture and shutter speed, but you won’t get photos with too much grain. You can always switch to manual ISO to override the cap if a particular shot calls for a higher ISO.
To access the auto ISO settings the Canon 6D:
Select the menu button
Select the 3rd shooting tab (3rd tab from the left)
Select “ISO speed settings”
Select “Auto ISO Range” and choose your desired minimum and maximum ISO.
I spent a long time intimated by ISO. But, at its core, it’s really very simple as long as you can remember these basics:
Low ISO = less Light = less grain
High ISO = more light = more grain
Noise Reduction In Post Processing
Topaz Labs Denoise AI
Topaz Labs is a third-party tool that works independently or integrates with Photoshop and Lightroom. It is an easy-to-use tool that does a better job at reducing image noise than any other tools I‘ve seen.