Definitions and FAQs

FAQ

Q: Why are there no FAQ’s?

A: No one has asked a question yet so how could there be anything that’s been asked frequently. Please ask any question in the comment section below

DEFINITIONS

Aperture: One of properties that controls the exposure. The variably sized opening inside the lens is the aperture size (often referred to as the f/stop). The smaller the opening (larger numbered f/stop) the more that is in focus (see Depth of Field) but less light reaches the sensor, which required either a slower shutter speed or more sensitive sensor setting (see ISO).

Depth of Field (DOF): This is the amount of space in an image that is in focus. This is controlled and/or altered by the following: 1) Aperture size (f/stop) the smaller the aperture (bigger f/numbers) the more that will be in focus. 2) Angle of view, the wider the angle the more that will be in focus. 3) Distance of the point of focus, the closer it is the less space that will be in focus (making macro photos all the harder). In portraits a small depth of field is often desirable to isolate the subject from the background.

Exposure: The resulting image from a combination of Aperture, Shutter Speed, and (ISO) Sensitivity that make an image.  Too much light (natural or artificial) and the image is overexposed and washed out (possibly too wide an aperture, too slow a shutter speed, or too high an ISO setting). Too little light and the image is underexposed and too dark. A good exposure is typically (although not always, and often not on this site) one that is represented on the histagram that goes from the left to the right, but not cut off at either end and the bulk of the histogram near the center.

Exposure (Adjusting): For every doubling or halving you do to Aperture, Shutter Speed, or ISO Sensitivity can do the opposite to the other and keep the same exposure. Here are the ISO “Whole Values” 100, 200, 400, 800, 1600, 3200, (and so on in both directions). Shutter speed numbers look similar, but cameras often round: 2 seconds, 1 second, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, (and so on). Apertures don’t look even close, even though they are just doubling and halving, the reason is f/stops represent the area of the opening, so there is a lot of geometry and something to do with the square root of 2… I’ll digress and say that the “whole” f/stops are: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16 (and so on mulitpling and dividing by 1.4 (actually the square root of 2 and then rounding)

ISO / Sensitivity: This is how sensitive the sensor (or film) is to light. In digital, this is achieved by cranking up the signal, when this happens noise is introduced to the signal. In general noise is undesirable, but not as much as camera or subject shake so the compromise is sometimes necessary.

Shutter Speed: The amount of time the sensor (in the old days film) is exposed to light. The faster the shutter speed the less blur, but it requires more light from the aperture or a more sensitive ISO.

A lot more to define as time permits… Vignetting, HDR, Exposure Blending, Camera Shake, Image Stabilization, Whatever else you need defined in a casual possibly inaccurate way.