I used to ask myself how to set the ISO setting. At one point I was even convinced that it should always be in the lowest value. Of course, this is not right at all, but if you just start, you will think of everything. It is, therefore, useful to go back to the definition of ISO.
What is ISO for?
In Traditional photography (with a roll) ISO (or ASA) was the indication of how sensitive a roll of film was for light. This sensitivity was qualified on numbers – 100, 200, 400, 800, etc. The lower the value of the film the more sensitive the movie and the less noise there will be on your recording.
In Digital photography ISO measures the sensitivity of the sensor. The principles of traditional photography remain. The lower the ISO value, the less sensitive your sensor is for light, and the finer your photo comes across.
High ISO values are generally chosen in dark situations to enable faster shutter speeds. For example, if you want to beat an Insport event and want to freeze action in worse light conditions. The higher the ISO value you select, the more granular the end result will be. Check out these examples though. Left is taken with an ISO of 100 and right is chosen for ISO 3200.
100 ISO is generally accepted as usual and will also give you beautiful pictures that bring little noise.
Most people tend to leave the ISO setting on AUTO. The camera will always adjust the ISO setting to the conditions in which the photo is taken. Your camera will try to keep the value as low as possible. But more and more cameras also give you the option to select the ISO setting yourself. When you choose to do this, you will notice that the adjustments made affect your aperture and the shutter speed required to take the shot.
In An example: if you increase the ISO value from 100 to 400, you will find that you can start using higher shutter speed and or a smaller aperture.
Questions you should ask yourself
If you are going to adjust the ISO setting, you should ask yourself the following questions.
Light – Is the subject well exposed?
Noise – Do you want to see noise in the picture?
Tripod – Do you use a tripod?
Movement – Is The subject static or does it move?
If there is enough light you will want less noise and use a tripod in a static subject, then you will easily be able to choose a low ISO setting.
If there is less light, then the choice for some more noise is not very unwise. Especially when you consider that maybe without a tripod works and the subject moves again. Then you will be able to use a higher ISO value with shorter shutter speed. But also remember the higher the ISO value, the more noise is going to occur. Multiple test shots with various ISO values can help you find the right setting.
Situations where a higher value may be required:
Sports events – reduced light and moving subjects.
Concert Photography – Here is often consciously less light present, and you may not always use a flash.
Museums and churches – you may not use a flash here often, and there is usually only atmospheric light present.
Birthdays – When blowing out the candles, but here again, as, with museums and churches, there is mainly mood lighting.
ISO is an integral part of digital photography where you need to be in control, you want to get the most out of your photos. Therefore, actively experiment with the setting and oversee the results.