As you begin to break into photography and figure out what it is you're doing with your smartphone or your DSLR camera you come across the setting of ISO. ISO stands for International Standards Organisation, which determines the level of sensitivity of your film. Although, now in the digital age, it affects our sensor.
The ISO is one of the three pillars of photography along with aperture and shutter speed. Together the three pillars determine the brightness, motion, and grain in any given photo that you take. Here's how ISO works. The smaller the number, the less sensitive your film or sensor is. When you have access to plenty of light, then you don't need your sensor to be sensitive. On the other hand, if you're in a room without natural light you might need to increase your ISO and if your taking photos at night you'll have to turn your ISO up as high has it can go.
On average, a camera's ISO can go anywhere from 100-6400 depending on the camera. High-end cameras now are reaching far beyond 6400, but there are issues with an increase of your ISO, even if your camera can reach far beyond 6400. As the ISO increases, it reaches a point where the quality of your image starts to deteriorate. The deterioration is also known as having a grainy picture. You'll see millions of little dots all over your image almost like it's pixelated. The grain that you're seeing causes a loss of clarity and sharpness which can be an artful tactic in some photos but more often than not creates a low-quality image.
There are some cases when a high ISO is the only option, the best example being night photography. To capture the light from the stars along with the landscape a high ISO is necessary, along with a small aperture and a long shutter speed. In almost any other case more light can be added either by flash, turning on more lights or using reflectors so that you can avoid increasing the ISO of your camera.
Here's the kicker, if you're taking photos with your smartphone you are even more limited in your low light photography abilities. A smartphone's ISO has a base ISO of 34 and can only go up to 1500. This is why you turn on that pesky little flash on your phone to see in the dark. (But that on-camera flash is the worst and deserves its own blog post). If you want full control over your ISO and the other pillars of photography the best way to get full control is to download a 3rd party camera app. Something like Camera+ will give you the customization you want.
If you are hoping to improve your photo skills understanding aperture, ISO and shutter speed. The best way to learn how these things work and how to use the three pillars best is to get out there and start taking photos. Use the camera you have under different lighting conditions and take as many pictures as you can. Trial and error is the best teacher there is. If you can't seem to get the images you're looking for you might just be in need of a professional, and that's where I come in!