ISO in digital photography refers to the sensitivity of the light sensor within the digital camera. While the fundamentals stay the same with digital photography the results of a noisier shot with a digital camera are often less pleasing to the eye than that which was shot on a film camera.

How do you choose the correct ISO setting for your shot? Much depends on your lighting and subject conditions. Higher ISO settings are often used in poor light, or in situations where flash is not appropriate, for example many museums do not allow flash photography. You can also use a higher ISO setting to freeze fast moving action, using a higher ISO allows for a faster shutter speed and in turn allows the photographer to freeze the fast moving subject. As mentioned above the trade off is a noisier photo.

In traditional film photography grain was often a desired effect especially in black and white photography where it can create mood and depth. It can be argued that the same result is difficult to reproduce in digital photography.

While noisy shots can be used in some cases and mainly in black and white photography it is often best to avoid noise in digital photography, the best way to simulate film grain in digital photography is to perform the effect using Adobe Photoshop, you can follow this link to discover more. Using Adobe Photoshop to produce film grain.

The most common ISO setting used is ISO 100, in most lighting conditions it will produce crisp shots with limited noise or grain.
If you decide to take the first step to better photography (taking your digital camera off of Auto Mode) will allow you greater flexibility and creativity in your photography. Most digital cameras have the option of manual mode, once you have changed your ISO setting you will notice the effect it has on shutter speed and aperture.

A huge advantage digital cameras have over their traditional film counterparts is the ability to change ISO on a per shot basis, with ISO settings from 80 to even 6200 in some cases we have never seen before such a versatility in creativity.

For example if you have a subject framed at ISO 100 and you now only change the ISO to 400 the subject is now over exposed. To rectify this you either need to select a faster shutter speed or a smaller aperture.

Situation where you might need a higher ISO setting

Sometimes our photography is governed by our situation and perfect conditions can not always be had, the following are some of the situations where you may need to increase your ISO setting.

Museums: Due to light deteriorating many artefacts many museums do not allow flash photography
Indoor Sports: Low light in many indoor events often require you to set a higher setting allowing for a faster shutter speed to still freeze fast moving subjects
Band Photography: Flash photography is normally not allowed when shooting live bands

Use a tripod or support yourself

In general it is better to use the lowest ISO possible that the conditions will allow, if possible always carry a tripod even a small one. I always carry a Giotto QU405M it is small and lightweight while still very versatile. If you do not have a tripod try supporting yourself against an object such as a wall for added stability.

Above all experiment, try taking the same shot with different ISO settings and see how it impacts the shot, experimentation is your best friend and will allow you to fully mature as a budding photographer.

Photo credits

Intro image by Kapkap