If you don’t see the term you’re looking for, do a “find” in your browser (Control-F or Command-F) and search for the term. It may have multiple names and be mixed in with something else.
(this turned into a long list… did I forget any? Comment below and I’ll update the list!)
Ambient or Available Light
The existing light in a situation, before adding any custom light. This could be window light, overhead lighting, a lamp on the floor — whatever is lighting your scene before you start to add and manipulate that light.
A mechanism made of “leaves” or “blades” inside a camera lens that opens and closes to let more or less light pass through (think of it like the spigot on a garden hose, allowing more or less water through). This not only restricts light, but also affects depth of field. A larger aperture that lets more light through creates a shallow depth of field. A small aperture restricts the amount of light and creates a larger depth of field. The measurement is a fraction, which is why a smaller number is actually a bigger hole. The correct way to write an aperture as an f-stop is “f”, then a slash, then the aperture number, like this — f/4.0. The “f” is the focal length of the lens, therefore f/4 is bigger than f/22. A smaller number is a bigger hole, however a smaller number is less (shallower) depth of field. (See: Depth of Field and Bokeh)
A camera’s exposure mode is typically one of four settings, designated as PASM (Program, Aperture priority, Shutter priority, or Manual). Aperture priority means the camera operator chooses the aperture, and the camera automatically chooses a shutter speed to balance the exposure. ISO may or may not be able to be automatic, depending on the camera.
Referring to the size of a camera sensor; “APSC” is measured as a roughly 22mm to 28mm × 15mm to 19mm sensor (APSC sensor sizes vary by manufacturer), which is notably smaller than full frame sensors, which match that of 35mm film. The smaller the sensor, the smaller, lighter and less expensive the cameras and lenses can be. However larger sensors generally have better low light performance and shallower depth of field than their smaller counterparts.
The width vs the height of an image. Most still cameras shoot in a 3:2 aspect ratio (also called 1.5:1, meaning the image is 50% wider than it is tall) or a 4:3 aspect ratio (or 1.33:1), and video is traditionally shot in a 16:9 aspect ratio.
The blurry background behind a subject in a shallow depth of field photo.
Capturing multiple images that cover a range of settings. Most commonly used for exposure, where an “ideal” exposure is determined but then additional photos are captured both darker and lighter, typically in 1 stop, or ½ or ⅓ stop increments, resulting in a series of photos that go from underexposed to overexposed. Bracketing can also be used for white balance, focus, or really any other setting a camera is capable of changing. Most cameras can automate exposure bracketing but only a few can automate other types of bracketing.
Buffer (in camera)
Internal memory in every digital camera that holds the photos while writing to the slower memory card. Think of it like RAM in your computer. Very very fast memory that can store the photos instantly as the camera creates them, but it’s limited in size because it’s expensive (like RAM). The camera first sends a photo to the buffer (virtually instant), and then it moves it from the buffer to the memory card (several seconds). If you’re shooting very high frames per second, you could potentially fill the buffer, and then the camera will stop shooting until the buffer is cleared enough for another photo to fit in there.
Bulb mode allows an exposure of any duration; as long as the shutter is held down (always done with a shutter release cable so as to not touch and move the camera). One the shutter speed settings of a camera, typically the longest exposure available is 60 seconds; the next stop “longer” is B for Bulb.
Shooting multiple photos in rapid sequence, as long as the shutter button is held down. Most cameras can shoot three to five frames per second, while some higher end cameras can shoot over ten frames per second.
A color fringing that can appear around areas of high contrast on lower quality lenses, usually showing up as purple or green. Most modern software can automatically remove this effect.
Clipping (highlights, shadows, exposure, color)
If an image is over or under exposed, and the highlights and shadows are beyond the limits of what can be captured or displayed, that data will be clipped. Most easily seen by photographing a white cloud or white shirt in full sun; without careful consideration, the details in the subject are likely to be overexposed and clipped, or lost. The viewer will the seen solid white instead of the pattern or texture that was originally there. Clipping can also happen in color (see: Color Space)
Cyan, Magenta, Yellow and blacK are the four colors used in basic printing. All printable colors can be achieved by combining Cyan, Magenta and Yellow. Technically, equal amounts of CMY will make black, however it’s a muddy black so all printers also include pure black ink. More advanced printers may also include additional colors in-between C M and Y to make prints more vibrant and realistic. Images on screen are represented in RGB, and to go from screen to print requires a conversion from RGB to CMYK.
(See: Hot Shoe). A cold shoe is a hot shoe mount without any electronics to communicate with any device. It is simply a universally sized and shaped mounting plate.
The act of standardizing a screen or printer by creation of a color profile so that what you see on one screen looks like what you see on another. Color profile devices are basically cameras that sit on your screen or print and view known colors, then build a profile so colors appear standardized and consistent.
Every printer and screen is unique. To make colors appear the same across multiple devices, devices are calibrated and that calibration is saved as a color profile. A profile can be sent to another user, so for example a print shop will create a profile for their printer, and make that available for download. Anyone wanting to print on their printer can install that profile on their computer, and on a their color calibrated screen, adjust colors of their image as they desire knowing with reasonable confidence that the print they receive will look like what they created on screen. Without accurate profiles, conversions are estimated and will never be exact.
A definition of colors that can be captured by a camera or represented on a screen or in print. If a color exists outside of a specific color space, it will be clipped. Most consumer computer screens and devices use an sRGB color space. Professional screens may utilize an Adobe RGB color space, and print exists in CMYK color space that is unique to that printer (see: Color Profile). When shooting, editing and printing photos, understanding color space is important to ensure that the colors captured are represented accurately on other screens and in print. Fortunately, most consumer devices all live within an sRGB color space, making it easy to ignore this concern.
They layout of a scene; where objects are placed in the frame. “Good” or “bad composition” is purely subjective but is generally considered either pleasing or displeasing. A photograph with good composition is seen as one that holds the viewers attention, encourages them to explore the image, and feels balanced (or perhaps intentionally unbalanced to convey an emotion). A bad composition feels unbalanced, incorrect, disconcerting, or any other range of opinions generally considered “bad”. There are “rules” of composition like the “rule of thirds” which is worth understanding and appreciating, if only so you can intentionally break the rule as your comfort and confidence in image creation grows.
Constant Light (LED, CFL)
Constant light simply means that a light is always on, such as the lights in your house, compared to a strobe or flash (see: Flash), which is only on for a very brief duration. Constant lighting is easier to work with because what you see is what you get. As you move and modify the light, you see that happening on your subject in realtime, compared to a flash where you can’t see the results of changes until you take a test photo. However constant lights, which typically come in the form of LED or CFL lights, are considerably less bright than flashes/strobes.
When calculating effective focal length on a non-full frame sensor camera, the “crop factor” is a number by which you multiply the focal length of a lens to calculate its full frame equivalent focal length. This has no effect on a photo; it is simply a measurement by which we are conformable with so we can compare lenses on different size cameras. (See: Full Frame, APSC and Micro Four Thirds). Also, see this video for a deeper explanation: https://youtu.be/gjtTeml-npY
Depth of Field
How much is in focus at once. A shallow depth of field has a small area of focus which creates a blurry background (bokeh), while a large depth of field shows more, or everything in focus. The depth is distance from the camera; for example with a shallow depth of field, and a subject in focus 1 meter away, another subject that is 1.5 meters away may be blurry. With a large depth of field, that 1.5m away subject could be just as in-focus as the 1m away subject. Focus is not an on/off thing; focus gets gradually less and less sharp as distance progresses.
A device (usually an opaque material) that spreads light over a larger area, making a softer light source. A soft box, or a diffusion panel, are common devices for diffusing, or softening light.
Dots per inch
Drone (or UAV)
(Unmanned Aerial Vehicle). From a photographer’s perspective, a drone is a flying camera — or a camera on a tripod that can be positioned anywhere, even 400 feet in the sky! While many see a drone largely for video, it’s an amazing still photography camera, too. The ability to position it high in the sky, hovering over water, mid-way up a canyon wall — nearly anywhere a tripod can not reach — is phenomenal.
DSLR / DSLM
Digital Single Lens Reflex or Digital Single Lens Mirrorless camera. 35mm film cameras are SLR cameras (DSLR without the D). An SLR is a single lens camera (not dual lens), where light passes through the lens, hits a mirror box and reflects through a prism, then ultimately out of the viewfinder so you can see it through the lens. At the time of exposure, the mirror flips out of the way, the shutter opens, and the film or sensor is exposed. On mirrorless cameras, there is no mirror, and the light hits the sensor at all times. What you see through the viewfinder is actually a screen, showing you exactly what the sensor sees.
The range of light that can be captured or displayed by any given device, usually measured in stops. The bigger the dynamic range a camera can capture, the darker the shadows and brighter the highlights can be, and still be recorded in a single image. Limited dynamic range means when exposing for the shadows (so you can see detail in the shadows) may result in clipping the highlights (see: clipping). Conversely exposing for the highlights results in clipping of the shadows. With a camera capable of larger dynamic range, you can capture details in darker and darker shadows plus brighter and bright highlights simultaneously. To overcome the limits of a sensor, HDR photography can be employed (see: HDR).
Every RAW file has a JPEG built into it so the camera can display the image on the back of the camera, and so any app in the world can view the file by looking at the JPEG and not having to decode the RAW. Some cameras embed ¼ or ½ size JPEGs, and some embed full size JPEGs. When you open a RAW file in any processor, you will likely see the image immediately, and then a brief moment later, it will be change. That’s the embedded JPEG you saw first, then the decoded RAW file once the software was able to process it.
The combination of shutter speed, aperture and ISO that determines the amount of light reaching the sensor to create an image. An underexposed image (too dark) or overexposed image (too bright) are results of too little or too much light reaching the sensor.
Exposure Compensation (EV +/–)
Manually over or under exposing an image for creative or corrective effect.
An accurate exposure (a photograph in which the scene is accurately reproduced from the real world) is controlled by three camera-adjustable controls; aperture, shutter speed and ISO. As one changes, one or both others must change to balance the exposure. These three controls make up the exposure triangle.
Fill or Bounce Light
Typically a secondary light source that adds illumination to a scene, filing in shadows created by the main or key light. This can be an actual light, or simply a reflector, bouncing light from the key light back onto the subject.
Flash or Strobe
A devices that creates very high intensity artificial light, emanating in a very rapid pulse (very short duration). A flash (usually referring to a small device that could be built into a camera, or attaches to a camera) or a strobe (usually referring to a larger device used in studios) fires at the exact moment of exposure to illuminate a scene. The amount of light coming from a strobe is extremely high in comparison to the ambient light. Even a small, inexpensive flash can put out an incredible amount of light for a very short time (measured in thousandths of a second).
Flash Sync Speed (incl. High Speed Sync)
The maximum shutter speed at which you can set your camera while shooting with flash. Most cameras have a max sync speed of 1/250th of a second. This is the shortest duration that the shutter can be entirely open. In any photograph, the shutter opens and closes in stages; typically a series of leaves open from top to bottom, revealing the sensor, followed by a second series of leaves which also travel from top to bottom, closing the shutter. In a flash photograph, the shutter opens, the flash fires, then the shutter closes. The flash must fire only while the shutter is completely open. On most cameras, when shooting over 1/250th of a second, the shutter starts to close before it’s fully open, meaning the shutter is never fully open, and therefore the sensor is never fully revealed. If you shoot higher than 1/250th with a flash or strobe, you will see black banding in the image which is actually the shutter blocking part of the image while the flash fired. High Speed Sync is a very specialized method of triggering the flash and the shutter in which the flash is triggered multiple times in extremely rapid fire pulses to keep in sync with the narrow opening of a moving mechanical shutter.
A measurement in mm of a lens, from the rear nodal focus point to the film plane. In “full frame” parlance, the standard by which most people think about focal length, a 50mm lens is a “standard” lens, while a 24mm would be considered wide angle, and a 100mm would be considered telephoto. However the field of view (which is what we are actually thinking about when we think of wide, standard or telephoto) changes depending on the sensor size (see: Crop Factor). A 50mm lens on a full frame sensor camera is “standard” field of view, while that same lens on a Micro Four Thirds sensor becomes a 100mm “equivalent” and is now a telephoto field of view.
The point at which an image through the viewfinder is sharp; not blurry. It is the point where reflected beams of light from a subject converge to a single point on the camera sensor.
Frames per second (FPS)
Number of photos (frames) a camera can capture per second. See “burst mode”.
Referring to the size of a camera sensor; “full frame” is measured as a 34mm × 24mm sensor, which matches traditional 35mm film and has become a standard size to base other sensor sizes off of.
Hair Light or Back Light
A second or third light, placed behind the subject pointing at the subject and towards the camera, usually to provide separation between the subject and the background. A typical example would be to create a slight rim light, or halo light, around a person’s head and shoulders to create a visible edge, ensuring they don’t visually blend into the background.
HDR (High Dynamic Range)
(See: Dynamic Range). HDR or High Dynamic Range photography combines multiple exposures (see: Bracketing) into a single image to reveal details in both shadows and highlights which could not normally be captured at once. HDR photography typically requires a tripod and a static subject as you are blending multiple images shot over a period of time.
HEIC / HEIF
(High Efficiency Image File Format or Codec) A modern compressed file format for images that stores roughly twice as much information (i.e. twice the quality) as JPEG does for any given file size. This is a new system that is starting to be used more widely, but is not yet universal. A photo captured in HEIC (such as on an iPhone running iOS 11 or higher) is readable across iOS and macOS devices, but may not be readable by some web browsers or other operating systems. This will change though and it is likely that HEIC will eventually replace JPEG as the industry standard.
A linear representation of luminance values (dark to light; left to right) on a scale that allows you to see if an image is over or under exposed. A histogram can be viewed in software, but also in camera so you can see at the time of exposure wether an image is too bright or too dark.
A connector on top of a camera for mounting a camera flash. The Hot Shoe is a universal shape and size, allowing flashes from any manufacturer to be used on any camera. Automated exposure (see: TTL Flash) is mostly restricted to like-brands (i.e. Canon flash on a Canon camera), however any flash can be triggered in manual mode on any camera. Since nearly every camera has one, the hot shoe is also commonly used to mount on-camera microphones, LED lights, or other accessories.
A standardized measurement of film or sensor sensitivity. The higher the number, the more sensitive it is. Higher sensitivity requires less light for an equal exposure, however higher sensitivity is also more prone to grain (film) or noise (digital sensors). Digital sensors have a “native” ISO at which the sensor performs its best. This is typically ignored for still photography but quite important to videography. Native ISO can be 200, 400, 800, or others, depending on the manufacturer.
(Joint Photographic Experts Group) A compressed file format that is universally standard and can be read by nearly any system in the world. It is lossy, meaning the more compressed the image is, the more data is thrown away. On a heavily compressed (low quality) JPEG, you will see artifacts, blocking in colors, and loss of detail. However a high quality JPEG is virtually indistinguishable from the original, at least to the naked eye. It is an efficient standard however it is quite old, and is slowly being replaced by HEIF which provides superior compression (smaller files) at higher quality.
A temperature reading of the color of light. Daylight is measured at about 5500˚K. Warmer, more orange colored light is lower temperature (i.e. 2400˚K for standard incandescent lamps), and cooler, more blue light is a higher temperature (i.e. 6500˚K for a cloudy day). In photography, changing a camera’s white balance is actually changing the color temperature of which it expects the scene to be. (see: White Balance).
Key Light or Main Light
The primary light source, usually artificial, to illuminate a subject. A traditional three-light setup includes a key, a fill and a hair light.
A standard exposure utilizes a relatively quick shutter speed to stop action. A long exposure keeps the shutter open for a longer period of time (measured in seconds or even minutes), so as to photograph extremely dark scenes without the aid of artificial light, or to capture dark scenes that can’t be externally illuminated, like the night sky. Long exposure photography requires a tripod and a static subject, unless the objective is to add motion blur to a scene.
A camera lens that allows extremely close focus, usually used for photographing small subjects such as bugs, flowers, or jewelry.
A camera’s exposure mode is typically one of four settings, designated as PASM (Program, Aperture priority, Shutter priority, or Manual). Manual mode means you have control over both the aperture and the shutter speed of the camera. ISO may or may not be able to be automatic, depending on the camera.
A count of how many pixels a camera can capture or a photographic file is, measured in millions of pixels. An image that measures 5,000 by 3,000 pixels would be 5000 × 3000 = 15,000,000 pixels, or 15 megapixels. Most modern digital cameras capture around 15 to 20 megapixels, while some cameras can go much higher. Megapixel count is NOT a measure of quality, however. Combining a small sensor with a high megapixel count requires smaller pixels (higher density) than a larger sensor with lower megapixel count. In this case, more is not better; bigger is better. There is a balance that camera manufacturers are always adjusting, trying to simultaneously achieve the highest quality and largest megapixel count possible.
Memory card (SD or CF)
Removable storage in your camera for storing photos. Think of it like a hard drive in your computer (see: Buffer to compare the RAM). SD and CF are different card types/sizes, and most cameras use one or the other; a few use both. You can have virtually infinite storage for your camera by carrying more and more memory cards. As a card fills up, you swap it out for another, until you can copy the photos from those cards to your computer for final storage.
The act of measuring light to calculate exposure. All digital cameras have built-in metering, which the operator can override as desired.
Micro Four Thirds (MFT or M43)
Referring to the size of a camera sensor; “Micro Four Thirds” is measured as a 18mm × 13.5mm, which is 25% the surface area of full frame sensors, which match that of 35mm film. The smaller the sensor, the smaller, lighter and less expensive the cameras and lenses can be. However larger sensors generally have better low light performance and shallower depth of field than their smaller counterparts.
An empty or largely unused/unoccupied part of an image, usually off to one side. In a photograph of someone standing against a blank wall, the large area of blank wall would be considered negative space. A photo of a flower where the focus is clearly on the flower (i.e. shallow depth of field) and there’s large area of “nothing” (blurry leaves, the sky, the ground), that empty area is negative space.
Neutral Density (ND) Filter
A photographic filter (piece of glass attached over the front of a lens) that restricts the amount of light entering the camera. This is typically use for two reasons. In still photography, it is used to create abnormally long exposures, for example to photographic a waterfall with a multi second exposure to create large amounts of motion blur, even when in full daylight where a long exposure would not be possible. In video, it is often used so the camera operator can shoot with a large aperture even on a sunny day. In still photography, you would simply raise the shutter speed to compensate for the additional light coming into the lens because of the wide aperture. However in video, you are much more restricted in shutter speeds, so the amount of light entering the camera must actually be reduced.
In high ISO photography, digital noise (or grain, if you’re shooting film) is expected. It appears as high contrast speckles on the scene. This can be reduced in software if it’s displeasing, however reduction in noise also reduces color contrast and sharpness. That said, modern software can do an incredible job of reducing noise and still maintaining excellent image quality.
Whether the camera (and therefore the photo) is help horizontal (also called landscape orientation) or vertical (also called portrait orientation).
When a photo is too bright, or at least brighter than the camera meter determines it should be, it is considered overexposed. This may be done creatively, on purpose, or in error. If an image is too far overexposed, then highlight data is likely gone, even when shooting RAW, and unrecoverable.
PASM Camera Modes
See: Program, Aperture priority, Shutter priority, or Manual exposure modes.
All digital images are made of pixels; a square block of data that is a single color (see: RGB). Zoom into a digital image extremely close (i.e. 16:1 or 1600%) and you can see individual blocks that make up the scene. Step back to 1:1 (100%) or farther, and the pixels become unnoticeable to the human eye, and blend together to make an image. Typical modern digital cameras capture millions and millions of pixels per image (see: Megapixel).
Pixels per inch
A polarizer filter (usually called Circular polarizer) filters out certain light waves, giving the appearance of darker skies, and also reducing or eliminating reflection and glare off of water or other reflective surfaces. It can be particularly beneficial when photographing wet foliage, where the glare from the leaves would almost completely block their color from being recorded.
Prime or Fixed Lens
A camera lens can either zoom (cover a range of focal lengths), or not zoom. A lens that does not zoom is called “fixed” or “prime”. Fixed lenses are less complicated and require fewer parts than a zoom lens, and so fixed lenses are usually better quality or faster for the price than a zoom lens.
Program, or Full Auto
A camera’s exposure mode is typically one of four settings, designated as PASM (Program, Aperture priority, Shutter priority, or Manual). Program (or full auto) means the camera determines both the aperture and the shutter speed. ISO may or may not be able to be automatic, depending on the camera.
Camera sensors don’t record an image like film does; they record data. That data is converted into an image by the camera’s processors or computer software. If you set the camera to RAW, it will record the “raw”, or unprocessed data into a file for processing later. If you shoot JPEG, then the camera captures the RAW data, converts it to an image, then discards the RAW data. If you set your camera to shoot RAW+JPEG, then you get both files.
Any surface that bounces light. A white wall can be used as a reflector, or a piece of aluminum foil, or a common mirror. Photographically there are many reflectors of various shapes and sizes and materials that you can buy, including pop-out reflectors with white, silver or gold surfaces for bouncing more or less light, and even warming the light that is being reflected.
How many pixels a file has, or also, how many pixels per inch. These definitions are unfortunately used interchangeably, but they do have different meanings. Example: The pixel count of a 4,000 × 5,000 pixel file is 20,000,000 pixels (20 megapixels). However when it comes to print, the pixels per inch becomes an important factor in the size and quality of the print. That same 4,000 × 5,000 pixel file could be represented as 100 ppi (pixels per inch), allowing a [4000 ÷ 100 = 40 inch] × [5,000 ÷ 100 = 50 inch] inch print. Without removing or adding pixels, that same file could also be represented as 300 ppi, making it only a [4000 ÷ 300 = 13.33 inch] by [5,000 ÷ 300 = 16.67 inch] print. Your computer screen has a fixed resolution as well; both in pixel size (i.e. 1920 × 1080) and density (i.e. 192 pixels per inch if it were a 10” screen). Finally, print has resolution, too. An inkjet printer may lay down hundreds or even thousands of dots per inch (now DPI instead of PPI). That doesn’t mean your digital file has to match that; if it did we could only print very small prints even from high resolution files. The printer interpolates (adds dots) and those dots bleed together creating a high quality, seemingly continuous tone (i.e. the dots can not be seen) print.
Red, Green and Blue. All digital cameras and screens represent every possible color by combining red, green and blue. The amount of a color used in a standard 8-bit device ranges from 0-255. RGB 0, 0, 0 is pure black. RGB 255, 255, 255 is pure white. RGB 255, 0, 0 is pure red, RGB 255, 255, 0 is pure yellow, and so-on.
Rule of Thirds
This is a general, simple rule of composition, where primary subjects should all along the thirds lines of an image. Looking through the viewfinder, if you were to draw two evenly spaced horizontal and two vertical lines, you would have divided the scene into horizontal and vertical thirds. The “rule of thirds” says that subjects should be on those lines. to feel “balanced” or “interesting”. For example a landscape photo should have the horizon line at the horizontal ⅓ or ⅔ line. Rules, however, were meant to be broken.
A light-sensitive device inside a camera that records the light data projected by the lens as data which ultimately is converted into an image. In digital photography, the sensor replaced the film.
Sensor Spots or Dust
Whenever changing lenses, especially on mirrorless cameras, the sensor is exposed to dust. Even the smallest speck of nearly invisible dust on the sensor can show as dark spots on your photos. Sensor dust is more visible at small aperture photography, where depth of field is vast, because effectively the dust on the sensor is closer to being in focus than on large aperture (shallow depth of field) photos.
A camera’s exposure mode is typically one of four settings, designated as PASM (Program, Aperture priority, Shutter priority, or Manual). Shutter priority means the camera operator chooses the shutter speed, and the camera automatically chooses the aperture to balance the exposure. ISO may or may not be able to be automatic, depending on the camera.
The button on the camera that takes the picture (and a half press will focus the camera).
Shutter Release Cable
An electronic cable that attaches to the camera to trigger the shutter without having to physically touch the camera. This is useful in low light, long exposure photography where even the slightest camera shake could result in a blurry photo.
The duration which the shutter is open, exposing the sensor (or film). For normal photography, this is measured in a fraction of a second, such as 1/125th of 1/1000th of a second. Long exposure photography cold have shutter speeds up to several seconds, minutes or even hours long.
SOOC (Straight out of Camera)
A term used to describe a photo that has no post-processing applied it it. This is the image exactly as it came out of camera. Technically this term can only be applied to JPEG files, since a RAW file by definition has to be processed by a computer before it can be viewed, however many will call a RAW file that has simply been opened and saved as an “SOOC photo”.
Stopped Down / Opened Up
Closing or opening the aperture on a camera lens to add or remove light. (See: Stops)
A relative measure of light. It is not absolute (i.e. “a stop of light” doesn’t tell you how much light there is), but relative to an existing scene (i.e. “add a stop of light”) does tell you how much to add. Stops are a common measurement in photography and one stop is half or double the previous measurement. Adding a stop is doubling the light; removing a stop is cutting it in half. A lens aperture is measured in stops on a scale that alternates between factors of 1 and 1.4. So the aperture scale, in full stops, is f/1, f/1.4, 2, 2.8, 4, 5.6, 8, 11 (technically 11.2 but we say 11), 16, 22 and so-on. The difference between f/4 and f/5.6 is that f/4 is twice as much light as f/5.6 (or, 5.6 is half the light of f/4). Therefore a two stop difference (say going from f/4 to f/8) is actually FOUR times, or ¼ times, the amount of light.
A lens used to bring far-away subjects closer to the camera, like binoculars or a telescope. Technically a telephoto lens is a type of lens that folds light in a way such that we don’t need a lens as physically long as its focal length would suggest. For example, a 300mm lens should have to have its rear nodal focus nodal point 300mm away from the sensor, yet many 300mm lenses aren’t even 300mm long. Through a process of positive and negative focus, lens elements inside the lens over-focus then correct focus so that the front nodal point appears to be farther away than it actually is. In practical use though, any lens over about 100mm is considered “telephoto”.
A series of photos taken over an extended period of time and either blended into a single image (i.e. a single image that shows the path of the moon across the night sky) or assembled into a video file, compressing time (i.e. several hours playing back in a few seconds).
“Through the Lens” flash photography is the most advanced, automated flash photography cameras do. Light output is measured and adjusted per photograph, measured a microsecond before the actual exposure, allowing accurate flash photography even in constantly changing situations (like a live event environment where the location and lighting is constantly evolving), and making complex multi-light setups very easy to control. Put the lights in position, fire a test shot, and then tell each light to be a little bit darker or brighter to adjust the scene as you like it — if necessary at all. That difference is maintained even as the environment itself changes.
When a photo is too dark, or at least darker than the camera meter determines it should be, it is considered underexposed. This may be done creatively, on purpose, or in error. If an image is too far underexposed, then shadow data is likely gone, even when shooting RAW, and unrecoverable.
Viewfinder; Electronic Viewfinder (EFV), Optical Viewfinder (OVF), LCD Panel
The viewfinder is a viewing “window” that you place your eye to, to see what the camera sees. On a dSLR, this is an optical viewfinder, showing the actual light as it exists coming through the lens and reflecting through the eyepiece (see: DSRL / DSLM). On a mirrorless camera, you’re seeing a “tv screen” showing exactly what the sensor is seeing, and how it will record the scene. Also on a mirrorless camera, you can get the exact same view on the rear LCD panel, which is often flip out or articulating, making certain shots (high angle, low angle, front facing) much easier to compose.
A darkening around the edges of a scene. This can happen happen in-camera, usually unintentionally on some wide lenses with a lens hood (literally very slightly blocking the edges of the scene), or can be added in software, intentionally so as to draw attention to the center of the image. If it’s unintentional and undesired, this can be corrected in software by brightening the outer edge to compensate for the darkening caused in-camera.
Wide Angle Lens
A lens that captures a very wide field of view, often used in landscape or interior photography.
Shooting with the aperture all the way open (at the lowest f/number), for the shallowest depth of field and most light gathering capability.
Every camera lens has a focal length. Fixed lenses are a single focal length. A zoom lens has a range, such as 24mm to 70mm and can be rotated to accommodate the photographer’s needs. Zoom lenses are more complex to make than fixed lenses, so are either lower quality, slower, or more expensive.