ISO - How Sensitive Your Camera is to Light
Bay Bridge Night. Shot at ISO 6400 at f/4.0 with a shutter speed of 1/13th of second.
Those of you that remember using actual film cameras will undoubtedly remember having to buy different speeds of film. You may remember such speeds as 100, 400, 800 and up. Generally, the way it works with film is that the lower the number, the less sensitive the film is to light, the higher the film speed, the more sensitive the film is to light.
So, if you were to take a picture on a bright sunny day, a very low film speed like 100, 200, or maybe 400 would all that would be needed. However, if you wanted to take a picture in a low light environment, say inside, or at night, you would need a film that is more sensitive, such as film speeds of 800, 1600, or even 3200.
Now you may think to yourself, what if I only have 100 speed film and want to shoot at night? Or what if I have 1600 speed film, and want to take some shots during the day? You can certainly do so! One simply needs to set the camera to the proper aperture and shutter speed combinations to get a proper exposure. Now you may ask, why don’t I just whatever film speed all the time, if I just need to set the proper aperture and shutter speeds? Like anything in life, there are right situations in which to use the right film speeds. Shooting at lower film speeds will give sharper and less grainy photos than shooting at higher film speeds. Shooting higher film speeds will enable you to take a photo where a lower film speed would require an aperture and shutter speed combination that would be impractical given the lighting conditions.
Classic Chevy at Alcatraz. Shot at ISO 1600 at f/3.2 at 1/4th of a second.
So far I’ve been talking about film speeds, while most of you reading this most likely are shooting with digital cameras. The above-mentioned film speeds directly correspond to the ISO settings on your digital camera. However unlike traditional film cameras, you aren’t stuck with a particular speed of film for an entire roll of film. You can change your ISO at will! So if you are shooting outdoors in daylight, set your ISO to the lowest in can go, typically 100 or 200. If you shoot indoors, or any place where its dark, set it between 400 and 800. If you want to do some night photography, some newer DSLR’s can go all the way up to 6400 and still give remarkably clean photos. My Canon 5D Mark 3 can be set all the way up to 102,400! Although I’d never shoot it that high.
This may seem a little confusing, but the thing to remember is to use the right ISO for the right lighting conditions. With digital cameras, you have the ability and flexibility to set the ISO to whatever you want, as often as you want. If you can master the relationship between ISO, aperture, and shutter speed on your camera, I’m positive that you will improve your photography!
Fireboat Under the Bay Bridge. Shot at ISO 100 f/8.0 at 1/320th of a second.