Pixel: The smallest unit of a digital image that can be represented or controlled.
Megapixel: One million pixels gridded into a pattern in the shape of a rectangle.
Resolution: The number of pixels that make up an image. An image that is 2048 pixels in width and
1536 pixels in height has a total of 2048×1536 = 3,145,728 pixels or 3.1 megapixels. One could
refer to it as 2048 by 1536 or a 3.1-megapixel image.
Image Size: Image size is a direct product of resolution, but may be "scaled" visually by resorting resolution.
For instance, a 5x7 inch image at a resolution of 300/inch would appear as 10x14 inches when the resolution is lowered
to 150/inch. The amount of pixels doesn't change, but the number of pixels per inch can change (the size of each pixel)
without changing the image size.
Aperture: Diaphramatic opening in lens that increases or decreases in size to control
amount of light that passes through. They are measured in fStops: f2.8, f4, f5.6, f8, f11, f16, f22.
Shutter: Curtain that opens for a specified amount of time, or “shutter speed” to
control the amount of light that passes through. These are measured in fractions of seconds.
Exposure: A combination of an aperture and a shutter speed that results in a specific
amount of light entering the camera.
Overexposure: Too much light entering the camera.
Underexposure: Too little light entering the camera.
Equivalent Exposure: Two combinations of aperture and shutter speed that allow an
equal amount of light into the camera. For instance, f8@1/30 equals f5.6@1/60...different
numbers, same amount of light.
Depth of Field: The distance between the nearest and farthest objects in a scene that appear sharp.