November 9, 2023, 2:32 pm | Read time: 3 minutes
The ISO value is a well-known term in photography. If set incorrectly, it can ruin a shot, but when set correctly, it can lead to excellent photos. But what exactly is behind ISO, and why is it important? Editor Rita Deutschbein explains in a new episode of TECHBOOK Basics.
First of all, ISO plays a role in all types of cameras, including system cameras, compact digital cameras, video cameras, and smartphone cameras. The abbreviation stands for “International Organization for Standardization,” an international coalition of national standardization organizations, whose primary task is comparable to that of DIN (Deutsches Institut für Normung) in Germany. In the past, standardization committees set ISO values to indicate a film’s light sensitivity. Today, the system is more commonly used to determine the light sensitivity of the camera sensor.
Why ISO Value Is So Important in Photography
Alongside shutter speed and aperture, the ISO value is one of the three fundamental exposure settings in photography. The ISO setting greatly influences image quality. If set incorrectly, the wrong amount of light hits the image sensor, resulting in overexposed or underexposed photos.
Depending on the lighting conditions, the camera’s ISO must be individually adjusted for each shot. In many modern cameras, the software handles this automatically. However, you can also adjust the value manually, for example, using the pro mode on a smartphone. This allows you to achieve special effects with exposure if desired.
Read also: How Does the Bokeh Effect Work?
The Optimal Exposure Setting
In principle, the lower the ISO, the more detailed the photo. However, the exposure should be high enough to prevent image noise and resulting graininess. In high light conditions, such as well-lit environments and bright sunshine, lower values are better. But if it’s rather dark, you should increase the ISO value to enhance the camera’s light sensitivity.
The following can be established as a guideline for the optimal ISO:
ISO 100: With really good lighting, a very low value is sufficient. Outdoors on sunny days, an ISO of 100 is generally ideal.
400: If it’s cloudy or you’re indoors, the ISO can and should be increased to up to 400.
800: An ISO of 800 is suitable for indoor shots without additional light sources.
ISO higher than 1000: Values from 1000 to 3200 are only needed in darkness with poor lighting.
Keep in mind that the ISO setting also affects the shutter speed. For example, changing from 100 to 200 halves the required exposure time. With low ISO values, it’s often better to use a tripod to prevent blurry photos. Higher values, on the other hand, allow for handheld photography. However, a higher ISO is not always the right choice, as increasing values also increase image noise. It’s better to gradually adjust the ISO upward and instead open the aperture further and increase the exposure time.