Guest post by Justin McKee
Have you ever taken a photo in a place where there is not much light and the photo looks really grainy? By grainy, I mean the photo looks more like a picture of sand than of your subject. The grainy appearance in photos is referred to as “noise.” You look at your camera and raise one (or both) eyebrows because you know you’ve taken good photos with this device in the past.
Why is it that the photo quality has now dropped to something you’d expect to see from a photo in the 1800s?
Your ISO is too high.
ISO is an acronym that stands for International Organization for Standardization. I’m not sure how they mixed up those last two letters — but I’ll live without that knowledge. Basically, an organization named ISO created a standard for image quality that all photographers, regardless of camera brand, follow. This group also sets standards for other products and services throughout the world so there’s consistency.
For photography, ISO simply means the camera’s sensor’s sensitivity to light. Different speed ratings of film are classified using the ISO system. The speed rating of film determines how long the film is exposed to light and how sensitive that film is to light.
In today’s digital world film is still around, but it is used significantly less because of the advances of digital sensor technology. A digital sensor replaces all film speed ratings and combines them into one unit that can be changed quickly and efficiently either automatically or manually by the user.
Here’s how ISO works: Similarly to shutter speed and aperture, ISO contributes to the exposure of a photograph and is set up with a numeric system that ranges from 50 to upwards of 102,400 (or more). Pro tip: Don’t use an ISO that high unless you REALLY need a shot. It’s not going to be a pretty picture. At all.
Unlike aperture, ISO’s numeric system isn’t backwards. The smaller the number, the cleaner the photograph; the bigger the number, the nastier the photograph. That noisy look to your photos starts to appear when your ISO gets too high. So why would you ever want to use an ISO more than 50 or 100? Because your shutter speed and aperture will suffer the penalty if you don’t.
An ISO that is really low creates a nice and clean image, but the sensitivity to light is diminished because of that. If there isn’t much light to work with, and you set your ISO too low, your aperture will need to be constantly wide open and your shutter speed will be so slow that your subjects, if they’re moving even just a little, will be blurred.
It’s OK to have an ISO that is high in some instances.
Photo editing software like Adobe’s camera raw plug-in can diminish the noise in a photograph and make it look better. That’s not to say software can fix every problem, but it definitely helps.
When shooting with a camera phone or point-and-shoot, you may need to go into the settings in order to manually change ISO. Generally, once you set a base ISO, the point-and-shoot will try to compensate by changing the shutter speed and aperture automatically.
Generally, when I go on an assignment to shoot photos or video (because a lot of the same photographic principles apply to videography), I like to determine what my ISO should be first before looking at shutter speed or aperture. If I’m outside and the sun is shining, I’ll probably keep my ISO at 100 or 250 because there will still be enough light left over for a faster shutter speed and an aperture that is closed down for an overall sharper photograph.
If I’m indoors, or in a really dark area, I’ll probably need to increase the ISO. This, along with my aperture being wide open, will help me have a shutter speed fast enough to limit subject blur.
At the end of the day, photography is a balancing act between shutter speed, aperture and ISO. Different situations call for different settings and learning how to adapt to create excellent photos is all part of being a photographer.
If you’re confused by how these numbers interact with each other don’t dismay. In the next post we’ll discuss a few different scenarios to help increase understanding of how all three of these settings work together and/or against each other.
Justin McKee is a small-town photographer with big ideas living in Michigan. In addition to portraits, wedding photography and video, he also enjoys wildlife photography. He always seeks to learn more about his craft.