The ISO, or sensitivity setting, on a camera is a measure of how much light the sensor needs to register an image.
While it may not be a primary concern for some, it can reveal itself as a powerful creative tool for more advanced photographers. Most modern cameras can automatically set the appropriate ISO for the prevailing lighting conditions, but as you develop your photography skills, you’ll learn to use ISO to your advantage.
ISO is one of the many controls inherited from photography’s film-using days, and it originally referred to a film’s sensitivity to light. However, because different digital cameras measure sensitivity differently, the same ISO setting may produce different results, particularly at high settings. This is why it’s important to understand how your camera’s sensor measures ISO and how it affects the image.
In general, a doubling of ISO indicates a doubling of sensitivity. This means that a higher ISO setting allows the camera to be more sensitive to light, making it possible to take photos in low light conditions without using flash or a tripod. However, increasing the ISO setting also increases the amount of noise or grain in the image. Therefore, it’s important to find the balance between the desired level of sensitivity and the level of noise that is acceptable for the image.
The ISO setting on a camera is a measure of how much light the sensor needs to register an image. It’s an important control inherited from photography’s film-using days. Understanding how your camera measures sensitivity and how to use ISO as a creative tool can greatly enhance your photography skills. It can be used to take photos in low light conditions, but it’s important to find the balance between the desired level of sensitivity and the level of noise that is acceptable for the image.
When it comes to camera settings, ISO plays a crucial role in determining the exposure of an image. In practice, low ISO settings, around ISO 100, enable photographers to use large apertures or long exposure times in bright light conditions. As ISO settings increase, shorter exposure times or smaller apertures can be used. It’s often said that image quality is better at low ISO settings than at high, but in practice, modern cameras, excluding the cheapest models, provide excellent image quality even at ISO 400 or faster.
The main impact on image quality at high ISO settings is image noise, which is comprised of random patterns of pixels or groups of pixels in which the colors are not based on light from the scene, and that tend to disrupt the definition of details.
In modern cameras, there is little practical difference in image quality in the range of ISO 100 to 400, or even 800; at these settings noise levels are visually acceptable. This means that photographers can use ISO settings that were once considered high as their operating default.
Another consequence of this is that for the first time in photography’s history, there is no premium to be paid for working in color over black and white.
Within a broad range, from ISO 50 to 800, photographers can choose sensitivity levels for artistic reasons, not technical ones. However, it’s important to note that some in-camera procedures, such as sharpening or increasing the dynamic range the camera records, do cause noise levels to rise.
ISO settings play a crucial role in determining the exposure of an image. Low ISO settings enable the use of large apertures or long exposure times in bright light conditions, while high ISO settings enable the use of shorter exposure times or smaller apertures in low light conditions.
Modern cameras provide excellent image quality even at high ISO settings, and the main impact on image quality is image noise. Additionally, photographers can now choose sensitivity levels for artistic reasons, not technical ones, and there is no premium to be paid for working in color over black and white. However, it’s important to note that some in-camera procedures can cause noise levels to rise.
The amount of noise in an image can have a significant impact on file size and image quality. When using high ISO settings, the resulting JPEG files may be larger due to the extra detail created by the noise, which is harder to compress. While any smoothing in an image, including blur from shallow depth of field, can cause file sizes to be slightly smaller, the difference is not significant.
Noise can be reduced, or even eliminated, using specialized software such as Topaz DeNoise. These softwares have the challenging task of separating the real details in an image from noise, and while they are effective at removing noise without blurring too much image detail, it’s important to note that some types of noise, particularly banding, are very difficult to remove. Topaz DeNoise, however, is capable of handling banding noise.
It’s important to note that de-noise processing can be slow on large files, and it’s not recommended to make a habit of it. High ISO settings are useful in low light conditions, but it’s also important to consider the impact of noise on image quality and file size. Using specialized software can help to reduce noise, but it’s not a substitute for using the appropriate ISO settings for the lighting conditions.
If you found this helpful, you might want to read my post about aperture, click here.