• Foto Ruta’s Quick Guide to ISO

    Foto Ruta’s Quick Guide to ISO

    Over the last couple of months Foto Ruta has shared several quick guides to help our followers hone their photography skills. We started with a quick guide to shutter speed, then covered the rule of thirds, aperture, and today we will be tackling the quick guide to ISO. Having even a basic knowledge of your camera and how it works can greatly improve the quality of your photos.

    Photo courtesy of Peter Harris

    In the days of analog cameras, one needed to change their roll of film when they wanted to change their camera’s sensitivity to the light. Film came in varying sensitivities depending on what light you would be working with. Now, in the digital age, we can simply change the sensitivity using your camera’s ISO setting. ISO (or ASA) refers to how sensitive the film or your camera’s sensor is to light. The lower the number (ie. 100), the less sensitive your film or camera’s sensor will be to light. The higher the number (ie. 800), the more sensitive your film or camera’s sensor will be to the light. Therefore, if you have lots of light, you need a lower ISO, and if you have low light, you need a higher ISO.


    Photo courtesy of Federico Casares

    ISO also has to do with graininess or “noise.” Higher ISO settings are usually used in low light situations so the photographer can use a higher shutter speed. However, using a higher ISO will result in a more grainy or “noisy” photo, such as the example below:

    Photo courtesy of 55Laney69

    A photo that is grainy is not necessarily a bad thing. It an artistic choice that each photographer can make. A photo taken at a low ISO will give you a more crisp photo, but will require a longer shutter speed, especially in lower light situations. Using an ISO might require that you use a tripod in order to avoid getting a blurry shot.

    Photo courtesy of Ed Parry

    Here is a rough guide to ISO:

    100 – 200 : Outside, sunny, bright day

    400 – 800 : Overcast day or evening

    1600 – higher : Low light situations where you want to capture moving subjects without blur

    In order to set your camera’s ISO, try using your camera in Program mode (often marked with a “P”). This will allow you to adjust your ISO while your camera will automatically choose the proper aperture and shutter speeds. Using ISO takes a little bit of practice, so program mode is a great way to start using ISO. Happy shooting!

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