What is ISO? Simply put, it’s the sensitivity of your camera’s sensor. The higher the number the higher the sensitivity. So what does that mean for you? Well, it means that once your shutter speed and aperture are set and you still don’t have enough light to properly expose your image then you can get more sensitivity by raising your ISO. The drawbacks? It can make your image look really “grainy” and less focused. That graininess is called noise.
Nerd Alert: There are a few kinds of noise but basically it is caused by amplification of the output signal to the sensor.
Creatively you may want to use a high ISO to get that grainy and rough feel if that is what you are going for. Beyond that we typically only adjust our ISO if we absolutely need to. So now let’s take a step back and learn about the basics.
ISO typically ranges from 100 to 6400. This will vary by camera manufacturer. Some start at 50 and some start at 200 but most will start at 100. They typically go up to 6400 while some only go to 3200 and some go all the way to 25600 or more. Ultimately, here is what you need to know: The lower the number the better the quality of your image. A lower number means the sensor will be less sensitive to light but it minimizes noise making your images nice and clean. Sensor technology is continuing to improve and noise control at higher ISO’s continues to get better. For the best quality images try to shoot at as low of an ISO as you can.