Why do you want to learn to take your camera out of auto and get control of your images? So you can capture your subjects and your scene, in any environment.
Okay, in order to understand photography, you have to understand exposure.
Exposure is the balance of light on the image sensor in your camera. A correct exposure has the the perfect balance of ISO, Aperture, and Shutter Speed. (The exposure triangle).
When you shoot with your camera in “Auto” or with your phone or other point and shoot, the camera does the thinking for you and creates the perfectly balanced triangle of exposure.
The camera sees the light, decides what you are wanting it to focus on and adjusts the exposure for you the most efficient way that it can.
The thing is… we have the AWESOME brains in our head and eyes on our face that can create (most of the time) an even better image by adjusting the triangle ourselves; this is why it takes more than a good camera and lens to create a great image in every scenario.
SO, what are ISO, aperture, and shutter speed?
ISO measures how sensitive the camera sensor is to light. Lower ISO (100, 200, 300) mean the camera sensor is less sensitive to light. These numbers are what you use out in the sunlight. Lower ISO gives your image less grain (or noise).
Higher ISO (800, 1,600+) mean the camera sensor is more sensitive to light; these are usually the ones you are getting to when you are shooting indoor without a flash or out in the evening when the sun is barely there. (Higher ISO means a grainer (or noise) image.
Aperture (alo referred to as depth of field or f-stop) determines how much light enters the camera through the lens. It gives the background of your photo more or less blur and lends (in my opinion) the greatest change to the overall look of the photo (if you are not trying to convey movement).
Shutter speed controls how long the light entering the aperture exposes to the image sensor. Shutter speed is measured in fractions of seconds (fast shutter speed 1/500s freezes movement while a slow speed of 1/50s blurs movement).
I will talk more about all of these things in detail later on, for now, let’s focus on how these three things (ISO, aperture, and shutter speed) balance to get the perfect exposure.
In order to tell if your image is exposed correctly, you need to use your light meter. Exposure is measured using light meters; all meters that are built into digital cameras are reflected meters. Reflected light meters attempt to read the amount of light in the scene your are trying to capture.
To help read the correct exposure, cameras have various metering modes. The three basic modes are: MATRIX OR EVALUATIVE, CENTER-WEIGHTED, and SPOT metering.
Now that we have discussed what exposure is, and how we can expose correctly, stay tuned for more details on ISO, aperture and shutter speed.