How to use iso levels in your camera for optimal results
The ISO levels in your camera might seem like a foreign terminology in the world of digital-filmless photography. But actually the term survived the process of digitization, and still continues to indicate the camera’s level of sensitivity to light, measured by the camera’s sensor (A former action that was done by the “good old” film).
What does ISO (AKA as ASA) stands for?
ISO is an international standard in photography that measures the level of the films or camera’s sensor’s sensitivity to light. The international ISO standard was based on the former American standard also known as ASA.
The higher the ISO gets - the sensitive the camera or film are to light. A photograph made at 400 ISO level will not result the same as one taken with a 100 ISO level - even if you use of the same shutter speed and aperture size.
The common ISO values in films and cameras are: 100 ISO, 200 ISO, 300 ISO and 400 ISO. Each increase in the ISO level in the camera brings a compatible increase in the sensitivity of the camera’s sensor or film to light, and effects the exposure values (for example, 400 ISO is twice as sensitive than 200 ISO).
ISO and your camera – How to adjust it and when
During sunny summer days it is recommended to select 200 ISO or 100 ISO. On winter days it’s probably best to use 300 ISO or even 400 ISO when the light is particularly low.
If you shoot in low light conditions and the camera signals you that the shutter speed and aperture size you chose will results with an over-exposure (a dark photo), consider using a higher ISO level (which is more sensitive to light). That way you won’t have to compromise the level of exposure you need with the use of the shutter speed or aperture size.
Taking pictures in the dark becomes easier with high-speed film (high ISO level). In this case – an 800 ISO film (in addition to an exposure length of 20 seconds).
What’s a grainy image and how to prevent grain
When shooting with high ISO film or camera in dark conditions, the picture may turn out grainy. The grains look a bit like a mosaic made out of small pieces and lacks “smoothness”.
Every image consists of pixels – as long as they are small they will look as part of a unified surface of color. On the other hand, once you enlarge the photo, the grains grow as well and in some cases can be easily seen. Grains appear, among other cases, once you increase the ISO levels in your camera (for example, once you shoot in dark conditions). The result one might receive is often granularity of the picture. The main reason for this phenomenon is that the camera finds it difficult to identify the differences between some color areas.
In order to prevent grains in your photo try to increase the exposure time or aperture size so that more light can enter the camera. At the same time select a lower ISO level in order to maintain your desired level of exposure.
The picture below illustrates an exaggerated granularity (created using computer editing software and not with the use of high ISO level in a camera)
How to determine the suitable ISO level for your camera
The ISO level in most advanced cameras can be set using the main menu window. In order to determine the desired ISO level in your camera press the button that marks the ISO and choose the level you’ve selected. (Read your camera’s manual for better and clear guidance).