This post highlights some basic terms related to photography. For each term a brief definition, how it can be controlled, what effects are expected, and tips are presented. The information given was primarily gathered in the references listed at the end of the post, which one could read for more details.
Exposure
Definition: It is simply the amount of light recorded on the camera's sensor (or film).
Control: The correct exposure is achieved balancing shutter speed, aperture, and ISO.
Effects: Too much light on the sensor causes overexposure, i.e. the photograph will be overly bright. Not enough light causes underexposure, i.e. the photo will be too dark.
Tips: 1) For a given ISO sensitivity, there are many combinations of aperture and shutter speed that will produce the same exposure. 2) Changing aperture also changes depth of field, while changing shutter speed alters the appearance of moving objects.
Shutter Speed
Definition: It is how long the shutter remains open to allow light through the sensor, and is generally given in fractions of a second (e.g. 1/500, which means the shutter remains open during 2 milliseconds).
Control: The intended shutter speed is set directly in the camera. Its range depends on the camera hardware, and may be from 30 seconds, or slower, to 1/4000 seconds, or even faster.
Effects: A slower shutter speed allows more light through the shutter. Conversely, a faster shutter speed allows less light through.
Tips: 1) When using a slower shutter speed, a tripod to hold the camera steady will surely be handy to minimize excessive blur on the photograph. 2) One may slow the shutter speed in the following scenarios: photographing in low lighting conditions, intending to give a perspective of movement in a moving subject, etc. 3) One would be interested in a faster shutter speed in the following scenarios: photographing a fast-moving subject (e.g. a running athlete) without blur (in this case use shutter speeds faster than approx. 1/300). 4) When photographing handheld, avoid shutter speeds slower than 1/30, unless your hands are remarkably still. 5) To freeze fast motion, e.g. splashing water, movement of insect wings, etc., use shutter speeds of 1/4000 or faster.
Aperture
[3] Nikon Website, Digital SLR Camera Basics (with a lot of animations to ease learning)
[4] Bryan F. Peterson, Basic Photo Tips: Aperture, Shutter Speed, and ISO (with some technical details explained)
[5] David Peterson, The Holy Trinity: Aperture, Shutter Speed, and ISO
Exposure
Definition: It is simply the amount of light recorded on the camera's sensor (or film).
Control: The correct exposure is achieved balancing shutter speed, aperture, and ISO.
Effects: Too much light on the sensor causes overexposure, i.e. the photograph will be overly bright. Not enough light causes underexposure, i.e. the photo will be too dark.
Tips: 1) For a given ISO sensitivity, there are many combinations of aperture and shutter speed that will produce the same exposure. 2) Changing aperture also changes depth of field, while changing shutter speed alters the appearance of moving objects.
Shutter Speed
Definition: It is how long the shutter remains open to allow light through the sensor, and is generally given in fractions of a second (e.g. 1/500, which means the shutter remains open during 2 milliseconds).
Control: The intended shutter speed is set directly in the camera. Its range depends on the camera hardware, and may be from 30 seconds, or slower, to 1/4000 seconds, or even faster.
Effects: A slower shutter speed allows more light through the shutter. Conversely, a faster shutter speed allows less light through.
Tips: 1) When using a slower shutter speed, a tripod to hold the camera steady will surely be handy to minimize excessive blur on the photograph. 2) One may slow the shutter speed in the following scenarios: photographing in low lighting conditions, intending to give a perspective of movement in a moving subject, etc. 3) One would be interested in a faster shutter speed in the following scenarios: photographing a fast-moving subject (e.g. a running athlete) without blur (in this case use shutter speeds faster than approx. 1/300). 4) When photographing handheld, avoid shutter speeds slower than 1/30, unless your hands are remarkably still. 5) To freeze fast motion, e.g. splashing water, movement of insect wings, etc., use shutter speeds of 1/4000 or faster.
Aperture
Definition: It is the opening in the lens that light shines through when a photo is taken. Photographers discuss different sizes of aperture in terms of f-stop numbers (e.g. f/5.6, f/8, etc.). The higher the f-stop the smaller the aperture.
Control: The proper f-stop is set directly in the camera. Its range depends on the lens and on the camera, and may be from less than one to as high as f/128.
Effects: A larger aperture (lower f-stop number) allows more light through the lens. A smaller aperture (higher f-stop) allows less light through the lens. Also, the aperture influences the depth of field (i.e. how much of the photograph will appear to be in focus) directly: a larger aperture gives a narrow depth of field, while a smaller aperture gives a wide depth of field.
Tips: 1) A smaller aperture is great for landscapes. 2) If one wants to photograph a subject in crisp focus but with a blurred background, then a larger aperture is more suitable. 3) Larger aperture is generally the best method to increase the exposure because the downside - less of the photograph being in focus - is often a desired result.
ISO
Definition: It is the light sensitivity of the camera's sensor (or film).
Control: The proper ISO number can be set through the camera's settings menu. Its range depends uniquely on the camera hardware, and may be from 100 up to 6400 or even higher.
Effects: A lower ISO number indicates less light sensitivity, i.e. less light is sensed on the sensor within a given period of time. A higher ISO number, on the other hand, improves the light sensitivity, i.e. more light is sensed on the sensor within a given time interval. Also, high ISO numbers introduce digital noise into the photograph, hence a compromise exists of taking the best photo in a given lighting condition using the lowest possible ISO setting.
Tips: 1) For outdoors photography, ISO numbers of 100 or 200 are fine; for indoors, 400 or 800 generally do the job. 2) Keep the ISO number as low as possible to decrease digital noise on the photograph. 3) To reduce the risk of camera blur when photographing dark scenes, it may be useful to increase ISO and choose faster shutter speeds. 4) A high ISO may be useful to optimally expose both the subject and the background in a poor lighting condition without using the flash, which has limited range.
White Balance
Definition: When the subject being photographed is under commonly available light sources (e.g. sun, fluorescent lights, etc.), the coloring of the subject changes accordingly to the light tint. To compensate this, a white balance is applied.
Control: The white balance is set directly in the camera. One can choose a balance specific for a given light source or let the camera adjust the proper balance automatically.
Effects: If the white balance is not properly set, the photograph will inherit the light source tint. For example, if a white object is under bluish light, the photo will contain bluish pixels, unless a proper white balance is used.
Tip: 1) Auto white balance will normally produce the desired results without the photographer having to worry about the type of lighting.
Tip: 1) Auto white balance will normally produce the desired results without the photographer having to worry about the type of lighting.
Depth of Field
Definition: It is the in-focus distance in front of and behind the focus point of a photograph. A narrow depth of field could be exemplified with a flower photo in which only the flower is in focus, while the background is out of focus. A landscape photo, where everything is in focus, could be an example of wide depth of field.
Control: The adequate depth of field is set by the aperture (f-stop) setting (wider apertures shorter depths of field; smaller apertures longer depths of field), lens focal length (longer focal lengths shorter depths of field; shorter focal lengths longer depths of field) and subject-camera distance (shorter distances shorter depths of field; longer distances longer depths of field).
Effects: Larger apertures as well as shorter subject-camera distances will cause narrower depth of field, i.e. only part of the photo will be in focus. Conversely, smaller apertures and longer subject-camera distances will result in wider depth of field, i.e. most of the photo will be in focus.
Focus
Definition: It is a measure of how clear a subject being photographed appears on the photograph. It is a function of a camera's lens and the current aperture setting.
Control: The focus can be adjusted manually (by means of the lens focus ring) or automatically (by means of the camera's autofocus system). Some cameras have continuous autofocus, which track and keep in focus moving subjects.
Effects: Out of focus photos will appear blurry, while in focus ones will appear clear.
Control: The focus can be adjusted manually (by means of the lens focus ring) or automatically (by means of the camera's autofocus system). Some cameras have continuous autofocus, which track and keep in focus moving subjects.
Effects: Out of focus photos will appear blurry, while in focus ones will appear clear.
Flash
Definition: It is an auxiliary light source usually built-in on cameras that helps improve lighting conditions in low-light areas or unevenly lit situations.
Control: The flash can be set automatically, with a preset mode, or manually. In the latter case, the photographer decides whether the flash will be used or not.
Effects: If the light from the flash is too bright, photographs will be too bright (overexposed); if it is not bright enough, photographs will be too dark (underexposed).
Tip: 1) Flash may be used to prevent blurred photos in low-light conditions (which otherwise would require slower shutter speeds) or to illuminate details in backlit subjects.
Control: The flash can be set automatically, with a preset mode, or manually. In the latter case, the photographer decides whether the flash will be used or not.
Effects: If the light from the flash is too bright, photographs will be too bright (overexposed); if it is not bright enough, photographs will be too dark (underexposed).
Tip: 1) Flash may be used to prevent blurred photos in low-light conditions (which otherwise would require slower shutter speeds) or to illuminate details in backlit subjects.
References:
[1] Ed Grabianowski, 10 Important Photography Terms
[2] Adam Dachis, Basics of Photography: Your Camera’s Manual Settings (with basic practical tips)
[4] Bryan F. Peterson, Basic Photo Tips: Aperture, Shutter Speed, and ISO (with some technical details explained)
[5] David Peterson, The Holy Trinity: Aperture, Shutter Speed, and ISO
[6] Star Valley Photo Club, Exposure (tables of aperture & shutter speed combinations, considering ISO of 100, for good exposure on sunny days, cloudy days, and indoors without flash)
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