Manual ISO and automatic ISO are both settings related to the sensitivity of a camera’s image sensor. However, they have different functions and applications.
What is ISO?
ISO in photography refers to the sensitivity of the camera’s image sensor to light. It is an important aspect of exposure alongside aperture and shutter speed.
When you increase the ISO value, the camera becomes more light-sensitive, allowing you to capture images in low-light conditions or use faster shutter speeds. However, higher ISO values can introduce digital noise or graininess, reducing image quality. On the other hand, lower ISO values are less sensitive to light and are typically used in well-lit situations, providing cleaner and sharper images.
Photographers can adjust the ISO setting based on the lighting conditions and their desired outcome. It’s important to strike a balance between the ISO, aperture, and shutter speed to achieve proper exposure while minimizing noise. Modern cameras often offer a range of ISO settings, including manual control and automatic ISO adjustment based on the camera’s metering system.
Manual ISO vs Automatisc ISO:
Manual ISO allows the photographer to manually set the ISO value. By manually adjusting the ISO value, the photographer can control the exposure of the photo. A lower ISO value (e.g., ISO 100) results in less sensitivity to light, while a higher ISO value (e.g., ISO 1600) provides more sensitivity to light. Using a higher ISO value allows the camera to use faster shutter speeds or shoot in low-light conditions without underexposing the photo. However, the downside of a higher ISO value is that it can introduce more image noise.
Automatic ISO is a setting where the camera automatically adjusts the ISO value based on the lighting conditions. The camera analyzes the ambient light and adjusts the ISO value to achieve a well-exposed photo. In sufficient light, the camera will select a lower ISO value, while in low-light situations, it will choose a higher ISO value. Automatic ISO is useful in situations where the light is constantly changing, such as capturing moving subjects or taking photos in different lighting conditions.
As photographer you can manually set the range between which the camera can choose your ISO value. With this setting you can avoid an ISO which is too high, which creates too much noise.
The choice between manual ISO and automatic ISO depends on the specific situation and the photographer’s preference. Manual ISO offers more control but requires the photographer to constantly monitor the exposure and manually adjust the ISO value as needed. Automatic ISO is convenient when you want to quickly capture photos without worrying about manually adjusting the ISO value, but it can sometimes result in higher ISO values than necessary, leading to more image noise.
Use of exposurecompensation with autmatisc ISO:
Exposure compensation is a feature available on most cameras that allows the photographer to adjust the exposure of a photo relative to the exposure determined automatically by the camera. When exposure compensation is used in combination with automatic ISO, it affects the exposure by the camera, including the ISO value.
When using exposure compensation with automatic ISO, the photographer can adjust the brightness of the photo without having to manually change the ISO value. For example, if you have a scene where the camera underexposes or overexposes the exposure, you can use exposure compensation to adjust the brightness. Positive exposure compensation (e.g., +1) makes the photo brighter, while negative exposure compensation (e.g., -1) darkens the photo.
In combination with automatic ISO, the camera will adjust the ISO value to achieve the desired exposure compensation. For instance, if you use positive exposure compensation, the camera may choose a higher ISO value to make the photo brighter. However, it could also mean that the camera goes to higher ISO values than you would prefer, resulting in more image noise.
It’s important to monitor the exposure and resulting ISO value when using exposure compensation with automatic ISO. If you find that the camera goes to high ISO values too frequently, resulting in unwanted image noise, you can switch to manual ISO to have more control over the sensitivity of the image sensor. Alternatively you can adjust your shutterspeed or aperture to reduce your ISO values.
Exposure compensation with automatic ISO can be useful in situations where you want to quickly adjust the brightness of the photo without manually changing the ISO value. It provides flexibility, but it’s important to keep an eye on the impact on image quality, especially at higher ISO values.