ISO Explained As I see It

What is ISO?

In Simple terms ISO is the sensitivity of light to the sensor/film. By now you would have seen settings like ISO 100, 200, 400, 800, 1600 etc. 

So What do these numbers mean? 

Basically a higher ISO number means that the film/sensor is more sensitive to light. So at ISO 200 it is two times more sensitive than ISO 100 and at ISO 400 it is two times more sensitive than ISO 200 and so on and so forth. This setting is great for the digital age as you can change your ISO whenever you need to without changing your memory card as back in the film days you would have to change your film when you wanted to change ISO. 

When Do I Use ISO?

ISO is used when you are in a situation where the lighting is very poor and you are unable/don't want to use flash I.E sporting events, indoor weddings, parties, evening shots. And we use it to increase the shutter speed to enable us to hand hold the camera/freeze motion as at ISO 100 you will find the shutter speed will decrease a hell of a lot during low light situation so in order to get the picture you desire in a low light situation you may need to play with the ISO settings.

What's The Downside To Higher ISO?

There is only one answer to this is my eyes and that is NOISE (grain in your pictures) used correctly a little noise can add to the image but used incorrectly it can make an image look awful. You need to remember this ISO tends to show itself more in the shadow rather than the highlights so noise will become more apparent in dark scenes.

What ISO Settings Do You Advise?

Personally I feel this is down to your individual taste and the situation you are in. For me during normal conditions I use between 100-200 ISO and for indoor low light situations I use 400-800 ISO. I have not done any night time shots without flash so have not stepped over 800 ISO as yet

I hope this has helped shed some light on ISO

Thanks for reading

James