Photography 101: ISO

This week we will be guiding you through how to maximize your DSLR camera. Whether you have one and leave it on the automatic setting, are thinking of taking the plunge but want to know the basics first, or you’re well acquainted with your camera’s features, a brush up on basics is never a bad idea. At the end of the week we will link all Photography 101 articles so you can easily access these helpful tools. You’ll be a pro in no time!

ISO (International Standards Organization) is the camera’s sensitivity to light. In film days the ISO was determined by the film speed used (Porta 160, Porta 400, Porta 800, etc.). You could choose a roll of film and stay with that ISO until you changed film. In digital cameras, ISO is the digital sensor and can be changed at any time. Moving the ISO up or down effects how quickly pixels gather data and record an image. The higher the ISO, the faster an image is recorded and less light is required. The lower the ISO, the slower an image is recorded and more light is required.

Is a faster ISO always better?
In short, no—a higher ISO will record an image faster so you may be tempted to use a high ISO all the time. However, there are drawbacks to shooting at a higher ISO: Images will have additional noise and the image is not as sharp. Today there is a wide range of cameras with varying ISO capabilities. You should practice with yours to see how far you can push the ISO before you start to see these side effects. 

Guidelines for setting your ISO:
Here are some general guidelines that will help you determine what ISO to use in various lighting.

Direct sunlight: 100-200
Overcast day: 400
Shade: 400
Indoors with lots of light: 400
Indoors with low light conditions: 800+

This was shot in bright direct sunlight so I set my camera ISO to 100. My aperture was at f/1.8 and shutter speed 1/1,000.

This image was taken in the shade so I set my ISO to 400, still giving me a wide range to move my aperture and shutter speed. I set my aperture to f/2.0 and shutter speed to 1/500 to get a proper exposure and freeze the motion of the veil.

This room had very little natural light. I wanted to show the warm and cozy feel of the room so I used the string lights and candles as my light source. This meant pushing my ISO all the way to 5000. My aperture was at f/1.2 and shutter speed 1/100. Because this shot was taken at such a high ISO it became a bit grainy.

It was an overcast day so I set my ISO to 400, aperture to f/1.8 and shutter speed to 1/1600.

The other factor in determining ISO is movement. If you are photographing action you may need to increase ISO to ensure the shutter speed is fast enough to freeze the action. ISO is one of the three components—along with shutter speed and aperture—that creates an exposure. So your shutter speed and aperture will also play a role in determining ISO.

When people think of freezing movement, action shots are what generally come to mind but remember this also applies to smaller movements (like a wiggling, laughing baby). For this image I wanted to be sure my shutter speed was fast enough to avoid any blur as she played. I set my ISO to 200, aperture to f/2.0, and my shutter speed to 1/400.

This reception was full of natural light streaming, but it was not falling directly on the tables, so I set the ISO to 800 to compensate for the lower light conditions. My aperture was at f/2.0 and shutter speed 1/160. 

The relationship between these three components will be talked about in greater detail in the exposure section.

All this information may seem overwhelming at first, but the best way to really understand ISO and its affect on an image is to practice in a variety of lighting situations. The great thing about digital photography is that you can see the results right away—it speeds up the learning process!

Additional Photography 101

Aperture

Shutter Speed

Exposure

Show Comments +