The Science of Photography 2 *
The Science of Photography 2
ISO, fstop, shutter speed, focus area, exposure, EV +/-, white balance, RAW, jpg, are just some of the settings you will encounter when using a DSLR camera (and even modern cellphone cameras). For this discussion I will assume we are using a modern DSLR camera. Keep in mind that for every setting on a camera there will be another setting that will be affected if you change that setting. The combination of settings is what gets you the final correct picture. I will explain the settings one at a time1. ISO - You will see this setting on every DSLR camera. ISO stands for "International Organization for Standards". This setting determines the camera's sensitivity to light. The lower the number the better the picture but also the longer the camera's shutter will need to be open to get a correctly exposed picture. If you have a lot of light this setting can go as low as 50 but if there is very little light (and depending on the camera) this setting can go up into the thousands. The price you pay for high ISO settings is a picture that is "noisy" a term used when you see a picture that looks "soft" and not sharp.
2. fstop or focal length - Every lens has a built-in iris that can open and close to let in more or less of the subjects reflected light and "expose" the digital sensor. When the fstop number is small e.g. f2.8 (a smaller number is a larger opening) and you are focused on the subject the distance that is in focus in front and back of the subject is very small. The background of your picture will be gradually out of focus and sometimes like in portraits this is desirable as it makes the subject stand out. When the fstop is a large number e.g. f22 the subject and most of the foreground and background are all in focus. The price you pay for these settings is this, a small fstop number opens the lens up wide for the light from your subject thus the speed your shutter opens, and closes can be very fast. This is why a lens with a very small f stop number, or "focal length" is called a "fast" lens. Typically, a lens is described by the widest f number it can achieve. A 35mm f2 lens is very fast and good in low light situations. It is also more expensive as the glass required to build it is larger in diameter