Night Photography Glossary
Welcome to The Night Photography Glossary. Over 275 terms about night photography, along with images to illustrate. The vocabulary of this fun and wonderful thing we do.
You can read those quarter-thousand words in two forms. The first is in our e-book version, which you can download by clicking below:
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250 Rule · a version of the 400 Rule adjusted for high-resolution and crop-sensor cameras; expressed as 250 / focal length in mm = maximum shutter speed in seconds
400 Rule · a formula for determining the approximate maximum shutter speed for a given full-frame camera and lens combination that will result in stars that appear as points in a photograph, as opposed to appearing as dashes or trails due to the Earth rotating during the exposure; expressed as 400 / focal length in mm = maximum shutter speed in seconds; [see “What's the Longest Usable Shutter Speed for Astro-Landscape?”
500 Rule / 600 Rule · older, generally obsolete versions of the 400 Rule that worked better with film and with older-generation, lower-resolution digital cameras
A
added light · light that a photographer adds to the scene via methods such as flash, light painting, Low-level Landscape Lighting, etc.
airglow · a natural phenomenon wherein sunlight interacts with particles in the atmosphere and scatters light around the Earth into a night sky; results in a colored “glow” of light (usually green, red, yellow or purple) seen most often near a horizon; a similar but unnatural effect known as “skyglow” is caused by artificial light; [see photo]
altitude · the distance of a celestial object above the visible horizon, measured in degrees
ambient exposure · the correct or chosen exposure for the ambient light of a scene, before accounting for any light or creative variation the photographer might add; sometimes referred to as the “base exposure”
ambient light · the available light in a given scene (moonlight, city light, etc.), as opposed to light added to the scene by the photographer
Andromeda · the closest galaxy to the Milky Way; one of only three celestial objects outside the Milky Way (along with the Magellanic Clouds) that are readily visible to the naked eye from Earth
asterism · a recognizable pattern or group of stars that may be part of a constellation, but is not an officially recognized constellation; for example, the Little Dipper (part of Ursa Minor) and the Teapot (part of Sagittarius)
artifact · in a digital photograph, pixels or groups of pixels that appear to be unnatural or incorrect due to an imperfection created when the image was edited, due to either technical shortcomings or manual error; for example, fringing around the edge of a masked area, blurs around a cloned area, etc.
astro-landscape photography (ALP) · a genre of photography in which earthbound scenes serve as a foreground for night skies
astro-modified · an indication that a camera has been mechanically altered to make it more suitable for astrophotography or astro-landscape photography by removing or replacing its infrared filter and possibly by adding a cooling unit
astronomical twilight · the darkest of three stages of twilight, when the sun is about 18 degrees below the horizon; [also see “civil twilight” and “nautical twilight"]
astrophotographer · a photographer who practices astrophotography
astrophotography · a genre of photography in which the photographer creates images of celestial objects, whether near-Earth (for example, the moon) with standard camera lenses, or in deep space (for example, a nebula or distant galaxy) often using telescopes and advanced image-stacking techniques
astro-tourism · recreational travel to destinations that are reputed for the quality of their dark skies
Archer, The · see “Sagittarius”
aurora · a celestial phenomenon of colorful moving “clouds” or waves of lights appearing in the sky over a polar horizon, caused by solar winds colliding with Earth’s magnetic field; [see photo]
aurora australis · auroras seen in the Southern Hemisphere; also known as “southern lights”; see “aurora”
aurora borealis · auroras seen in the Northern Hemisphere; also known as “northern lights”; see “aurora”
auroral corona · rays of auroras converging to form a cone or crown shape, sometimes visible when the zenith of an aurora is directly overhead [see photo]
auto ISO · a camera feature wherein the camera uses a reading from its internal light meter in an exposure algorithm to automatically set an ISO based on the photographer’s choice of shutter speed and aperture; not generally an effective feature for night photography
autumnal equinox · an equinox that occurs in the fall—September in the Northern Hemisphere, March in the Southern Hemisphere
azimuth · the distance from north of a celestial object, measured in degrees, with north being 0, east 90, south 180, west 270, etc.
B
backlight · light that hits the subject from behind (from the camera’s perspective); [see photo]
Bahtinov mask · a device placed in front of a lens (like a filter) that diffracts light in a way that eases the task of focusing on stars; [see photo]
ball head · a tripod head with a ball-and-socket construction that enables the photographer to easily and quickly move the camera on multiple axes simultaneously; [see photo]
base exposure · see “ambient exposure”
Big Dipper · an asterism (within the constellation of Ursa Major) visible in the Northern Hemisphere that a stargazer can use to locate Polaris
black card · a black, rigid board used to hide a light source from the camera’s view during a long exposure; [see photo]
black moon · the appearance of an “extra” new moon during a specific time period; most commonly the “black moon” label is applied to a second new moon within one calendar month, though originally the term indicated the third of four new moons in one season
blend · a digital image created by combining more than one exposure or photograph; for example, a blue hour blend or a focus stack
blue hour · the period of twilight (from roughly the beginning of civil twilight to midway through nautical twilight) when the sky and landscape are indirectly illuminated by shades of cool light created by sunlight coming from below the horizon and reflecting off the atmosphere onto the landscape; [see photo]
blue hour blend · see “twilight blend”
blue moon · the appearance of an “extra” full moon during a specific time period; most commonly the “blue moon” label is applied to a second full moon within one calendar month, though originally the term indicated the third of four full moons in one season
Bortle scale · a measurement of how dark a night sky is in a given location; skies are measured according to nine ratings, from Class 1 indicating a pristine dark sky to Class 5 indicating what might commonly be found in suburban areas to Class 9 indicating thorough light pollution (i.e., very few visible stars) as seen from the middle of a major city
Bulb mode · a camera setting that changes the function of the shutter release to open the shutter when the photographer presses the button and then to close the shutter when the photographer releases the button; also see “Time mode”
bulb ramping · modifying exposure settings during successive of frames photographed during changing light, such as starting the succession in daylight and ending in darkness; usually automated with an advanced intervalometer; often used when shooting for a time-lapse video; sometimes referred to in short as “bramping”
C
camera slider · a mechanized (either manual or automated) mount that moves a camera gradually along a track; used for smooth tracking during a series of exposures, such as for producing a time-lapse video; [see photo]
car trail · a light streak in a scene caused by the lights of an automobile driving through the scene during a long exposure; [see photo]
Cassiopeia · a constellation visible in the Northern Hemisphere that a stargazer can use to locate Polaris
civil twilight · the lightest of three stages of twilight, when the sun is about 6 degrees below the horizon; also see “nautical twilight” and “astronomical twilight”
chromatic aberration · an occasional distortion that results in red, green or blue light not aligning properly in a digital image when viewed at pixel level; more prevalent when using wide-angle lenses; can be fixed in post-production; [see photo]
chromatic noise or chroma noise · see “color noise”
cityscape · a photograph that depicts a city skyline, usually photographed from a distance with a normal or telephoto lens [see photo]
color calibration · the process of using software to build a color profile for a device (for example, a camera, monitor, printer, etc.) that interacts with profiles of other devices to ensure that colors are rendered equally and accurately when digital images are displayed or printed
colorimeter · a device used to measure color for the purpose of calibration; [see photo]
color noise · image noise in the form of variations of color in adjacent pixels or groups of pixels, seen mostly in an image’s highlights or shadows; most often caused by photographing at high ISOs or by underexposure; also known as “chromatic noise” or “chroma noise”; [see photo]
color temperature · the quality of light in terms of how “cool” or “warm” it appears; measured in K, or degrees Kelvin; lower temperatures (for example, 3000 K) are warmer-toned, while higher higher temperatures (for example, 8000 K) are cooler-toned
color temperature filter · also referred to as a “color correction filter,” a filter or gel that alters the color temperature of the entire spectrum of a light source, as opposed to a color filter that eliminates all but one color’s wavelength of light; useful for color-correcting a light source, such as a flashlight, for creative control over colors in a photograph; [see “Level Up With Light Painting: Correcting the Color of Your Flashlight"]
comatic aberration or coma · a distortion caused by the physics of lens mechanics that results in stars that look like small triangles or flying saucers, particularly in the corners of the frame; produced to different extremes by different lenses, and can be mitigated by stopping down the lens; [see “How to Test Lenses for Coma”]; [see photo]
comet · an icy and sometimes rocky celestial object that, when approaching the sun, warms and then emits gases that appear to be a long tail when viewed from Earth; [see photo]
constellation · a group of visible stars that form a perceived outline or pattern, typically representing an animal, mythological person or creature, or inanimate object; 88 constellations are considered contemporarily “official,” though other cultures are known to have identified and named others in the past
corona · the outer layer of the sun, visible during total solar eclipses [see photo]
crescent moon · an intermediate phase of the moon that occurs between new moon and either first or last quarter, as either “waxing crescent” or “waning crescent,” respectively; named for its crescent shape; [see photo]
D
dark-frame subtraction · a processing technique for reducing the effect of long-exposure noise; a dark frame (usually created with a lens cap mounted on the lens) of the same exposure made on-location is layered with the actual image, and then the hot pixels are negated by the software
dark sky festival · an organized gathering of night sky enthusiasts, often astronomers and night photographers, held in dark-sky areas such as national parks
Dark-Sky Park · an official designation (with various tiers) from the International Dark-Sky Association recognizing a specific place for the quality of its night skies and its efforts to preserve darkness
day-for-night · a technique for creating what appears to be a night scene by drastically underexposing a photograph in daylight
dead sky · a sky devoid of any visual characteristics other than blackness, due to complete, dense cloud cover unlit by any nearby ambient light sources
December solstice · a solstice that occurs in December; in the Northern Hemisphere it would be a winter solstice, in the Southern Hemisphere a summer solstice
deepscape · a photograph that depicts a landscape in front of a deep-space object in the sky
deep-sky photography · also known as “deep-space photography,” a genre of photography in which the photographer creates images of celestial/astronomical objects in deep space (for example, a nebula or distant galaxy) often using telescopes and advanced image-stacking techniques
DeepSkyStacker · a PC-based software application that enables an astrophotographer to stack multiple frames of deep-sky images to increase the visibility of dim celestial objects and to reduce visual noise in the final image
depth of field · in a photograph, the distance between the closest and farthest points that appear acceptably in focus
diffused light · light waves that are scattered, often by being reflected or passing through a translucent object; appears “soft,” and doesn’t cash harsh shadows
direct light · light waves that hit an object with little or no interference between the light source and the object; appears “hard” and casts well-defined shadows with hard edges
double processing · processing the same image file with two different results and then blending the two resulting images; for example, a noise blend
downsize · to decrease the resolution of a digital photograph
dpi or dots per inch · a measure for the number of ink dots in one linear inch applied to paper by a printer; often erroneously used to indicate “ppi,” or the “pixels per inch” of a digital file or camera sensor
DSLR · a ubiquitous acronym for “digital single-lens reflex camera”; a camera, usually featuring a mount for interchangeable lenses, as well as a mirror and pentaprism combination that projects the image onto an optical viewfinder for composing and focusing, with the mirror mechanically flipping out of the way to allow for the light to be projected onto the digital sensor when the shutter is opened
dust lane · the dark band of interstellar dust that dissects the Milky Way galactic core as seen from Earth
E
earthshine · the dim glow of the unlit portion of a crescent moon, caused by sunlight reflecting off Earth and onto the moon surface
equatorial mount · a tracking mount designed to move the camera to compensate against the rotation of the Earth, allowing for longer night-sky exposures that maintain sharp stars; also known as a “star tracker”; [see photo]
equinox · the semiannual day or time when the sun aligns directly over the equator, resulting in a relatively equal duration of day and night worldwide; individually referred to as “spring equinox” or “vernal equinox” and “autumnal equinox,” or “March equinox” and “September equinox”
F
field of view · the horizontal, vertical or diagonal dimension (or, the width, height or diagonal) of what a camera and lens combination “sees,” measured in degrees; for example, a 24mm lens on a full-frame camera has a field of view of about 74 degrees in width—meaning it can “see” 74 horizontal degrees of the total surroundings (360 degrees) around the camera position
filter · a translucent gel, plastic or glass sheet that changes a quality of light as it passes through before impacting the camera sensor; usually mounted to the front of a lens, but can also be mounted inside some lenses, or in front of a light source
fireball · an uncommonly bright meteor, widely defined as being brighter than Venus appears to the unaided eye; the glow from a fireball can linger for seconds to minutes
first quarter · the second of the primary phases of the moon, occurring between new moon and full moon, with an illumination of 25 percent; see “moon phase”
flag · to block a portion of the light emanating from a light source, in order to keep the light from spilling onto elements of the scene where it’s not needed or wanted
flash · see “speedlight”
focus stack · a technique for increasing apparent depth of field by blending different frames of the same composition photographed at different focus points; generally performed in post-production, but a few cameras can accomplish the task in-camera
fringing · a lightening, darkening or discoloration of pixels along contrasting edges in a digital image, often caused by overusing a particular processing technique such as sharpening or masked adjustments; [see photo]
frontlight · light that hits the subject straight-on (from the camera’s perspective); [see photo]
full moon · the third of the primary phases of the moon between first quarter and last quarter, with an illumination of 100 percent; see “moon phase”; [see photo]
G
galactic center or galactic core · the central cluster of stars in the Milky Way as seen by an observer on Earth; commonly referred to as just “the Milky Way,” but other parts of the Milky Way can be seen (in a dark sky) stretching from horizon to horizon at any time of year; [see photo]
gibbous moon · an intermediate phase of the moon that occurs between full moon and either first or last quarter, as either “waxing gibbous” or “waning gibbous,” respectively; derived from the Latin word gibbus, meaning “hump,” for the phase’s hump-like appearance
golden hour · the period of daylight after sunrise and before sunset when the sky and landscape are illuminated by warm tones of light; the warm color temperatures are created by the sun passing through more atmosphere than when the sun is overhead, which filters out most of the blue light; [see photo]
GoTo mount · a computerized tracking mount that automatically aims a camera lens or telescope at a celestial object that the user selects from an attached or integrated database of astronomical coordinates
H
halo · see “lunar halo”
HDR · a acronymn “High Dynamic Range,” a processing technique for combining different exposures of the same composition in order to reveal detail in both shadows and highlights when achieving the same result would not have been possible with a single exposure; useful for photographing artificial light sources at night; [see “Processing HDR Images for Urban Night Photography” and “When HDR is the Right Choice for a Night Scene"]
headlamp · a light worn on the head to allow the wearer to illuminate their surroundings without using their hands
herringbone effect · an artifact sometimes seen in stacked images wherein a herringbone pattern appears within the blur of an object moving during the series of exposures; often seen in clouds that were moving during a stack of night sky images; [see photo]
high ISO noise · digital noise in an image created by a high signal-to-noise ratio when images are photographed at high ISOs; [see photo]
high ISO noise reduction · an in-camera or post-production algorithm that reduces the effect of luminance noise introduced by exposing a photograph at a high ISO
high ISO test · an exposure test run at a very high ISO (for example, ISO 51,200) in order to determine composition or correct exposure equivalents without waiting for the longer shutter speeds that testing at lower ISOs would require
high pressure sodium vapor light · a type of gas-discharge light source that causes a strong orange color cast in night photography that can be deemed as unfavorable; before the adoption of LED lighting, high pressure sodium vapor lights were the most common type found in urban settings; [see photo]
hot pixel · a photosite on a camera sensor that essentially “blows out” during an exposure, often caused either by the sensor overheating (such as during a long exposure, i.e. long exposure noise) or by a faulty photosite; appears in an image as a bright red, blue, green or white pixel; [see photo]
hyperfocal distance · the nearest point of focus—for any given focal length, aperture and camera format—that will keep infinity in acceptably sharp focus; [see “Use Hyperfocal Distance to Maximize Depth of Field at Night"]
I
IDA · see “International Dark-Sky Association”
image stacking · a set of processing techniques that involve layering multiple images to create a single final image; for example, star stacking, focus stacking, meteor radiants, noise reduction, etc.
incandescent light · a type of light source that uses a filament in a vacuum; tends to produce a pleasing warm light when used with appropriate white balance settings in night photography
infinity · 1. an abstract point that is the farthest distance in space away from a given point; 2. the farthest distance a lens can focus at
intermediate moon phase · one of four moon phases that occur between the primary phases of new, first quarter, full and last quarter; intermediate phases are waxing crescent, waxing gibbous, waning gibbous and waning crescent; see “moon phase”
International Dark-Sky Association (IDA) · a nonprofit organization based in Arizona dedicated to preserving night skies by reducing the effects of light pollution; the IDA works with regions to designate International Dark Sky Communities, Parks, Reserves, Sanctuaries and Places
International Space Station (ISS) · a space station in low Earth orbit that can sometimes be seen crossing a dark sky; appears as a light streak in a night exposure
intervalometer · a remote shutter release that a photographer can program to open a camera shutter after a programmed delay, for a programmed amount of time, at programmed intervals; used for automating the process of operating a camera shutter for a series of timed exposures and/or repetitive shutter actuations; [see “Mastering the Intervalometer for Night Photography and Long Exposures”]; [see photo]
Inverse Square Law · a law of physics describing the rate at which the intensity of light decreases as the distance between the light source and an object increases; the law states that light intensity is inversely proportional to the distance from the light source squared; practically speaking, doubling the distance between a light source and an object results in one-quarter of the light reaching the object
Iridium flare · a tapering burst of light seen in a night sky caused by the sun reflecting off an Iridium satellite as it passes overhead; uncommon nowadays as the Iridium fleet has been replaced with satellites that don’t create the same phenomenon, and only a few of the 66 older satellites are still in orbit; [see photo]
ISO invariance · the quality of a camera wherein photographs created at the same shutter speed and aperture—but at different ISOs—can be adjusted in post-production without a noticeable variation of image noise
ISS · see “International Space Station”
J
June solstice · a solstice that occurs in June; in the Northern Hemisphere it would be a summer solstice, in the Southern Hemisphere a winter solstice
K
Kelvin · a scale for measuring the color temperature of light, from 1000 to 10,000; for example, daylight is about 5500 K
Kp · a measurement of how intensely an oncoming solar storm is expected to interact with Earth’s atmosphere; in practical use, it serves as a predictor of the chances of seeing auroras
L
L bracket · a tripod-mountable plate that aligns with both the bottom and left side of a camera (in the shape of an L), which allows the photographer to quickly switch from mounting the camera horizontally and vertically without moving the tripod head; [see photo]
Large Magellanic Cloud · see “Magellanic Clouds”
last quarter moon · the fourth and last of the primary phases of the moon, occurring between full moon and new moon, with an illumination of 25 percent; also known as “third quarter moon”; see “moon phase”
LED · a light source that is activated by current flowing through a semiconductor; often arranged in arrays to produce a brighter total light, such as with a light panel
LENR · see “long-exposure noise reduction”
lens condensation · dew that forms on a lens element when the relative humidity is high and the temperature drops to near or below the dew point
lens flare · stray light recorded in a photograph due to a bright light source reflecting off a lens element at a direct angle; occurs most often when a larger bright light source is in the composition, but can also occur when the light source is just outside the frame; [see photo]
lens hood or lens shade · an opaque device that attaches to the front end of a lens, most commonly used to prevent or reduce lens flare; can also be used to prevent precipitation from falling on a lens’ front element, or to delay or prevent lens condensation
leveling base · a tripod attachment that allows for a camera to be leveled with the ground on both horizontal axes more easily than with standard equipment, in order to accelerate the process of setting up a photo for which that is ideal, for example, a panorama; [see photo]
light drawing · a more nuanced technique of light writing that involves creating planned-out shapes and/or designs, as opposed to simply moving light sources through the scene; [see photo]
light graffiti · a term used in some light writing circles to refer to creating words or recognizable shapes by drawing in the scene with a light source during a long exposure; [see photo]
lighting · a general term in many areas, but in night photography refers to a group of techniques used to add illumination to a scene; for example, light painting, light writing and Low-level Landscape Lighting
lighting ratio · the amount of light from one source compared to the amount of light from a second source; for example, a 2-to-1 lighting ratio would indicate that twice as much light is provided from one source than from the second; [see “Balancing Ambient and Added Light to Achieve Your Objective"]
light painting · 1. the technique of using a hand-held light source to illuminate elements of a composition by shining the light onto those elements; [see photo]; 2. also used by some generically to refer to “light writing,” but the distinction is meaningful
light pillar · a vertical shaft of light extending from the horizon during twilight or nighttime, caused by either sunlight or moonlight radiating from below the horizon (i.e., before sunrise or moonrise, or after sunset or moonset) and reflecting off high-altitude ice crystals; also known as a “sun pillar,” “solar pillar” or “moon pillar”
light pollution · light from artificial sources that reduces or contaminates night skies; for example, city lights glowing on a distant horizon; [see photo]
light pollution filter · a filter that reduces the color-altering effect of sodium vapor lights (common in and around urban areas) on a night sky; [see photo]
Lightroom · the industry-standard software made by Adobe for cataloging, editing and exporting digital photographs
light stand · a stand, usually like a lightweight tripod, used for holding a light source; [see photo]
light source · any object that creates light to illuminate a subject or a scene; for example, a flashlight, LED panel, phone screen, candle, streetlamp, moon, etc.
light writing · the technique of using a light source to “write” with light in a composition during a long exposure by aiming the light source back toward the camera; referred to by some as “light painting,” but the distinction is meaningful; [see photo]
Little Dipper · an asterism that is part of the constellation Ursa Minor and contains Polaris
live view · a digital camera feature that allows the LCD to be used as a relatively large electronic viewfinder; useful in night photography for determining composition and focus in low-light conditions
LLL · see “Low-level Landscape Lighting”
long exposure · not defined as a specific length, but rather any shutter speed that is longer than commonly used in general photography applications
long-exposure noise · bright red, green or blue pixels (i.e., hot pixels) that appear as flecks in an image; created by a sensor increasing in temperature during a long exposure; the effect can be accelerated and exacerbated in warmer ambient temperatures and low-humidity conditions; [see photo]
long-exposure noise reduction (LENR) · an in-camera feature that reduces the effect of hot-pixel color noise introduced by long exposures
Looney 11 Rule · a formula for calculating the approximate base exposure of a full or nearly full moon; expressed as shutter speed of the reciprocal of the lens focal length, with an aperture of f/11 and an ISO of 100; for example, for a 50mm lens, the exposure would be 1/50, f/11, ISO 100
Low-level Landscape Lighting (LLL) · the technique of using stationary lights set to dim levels to illuminate elements of a composition in very low ambient light; the dim added light is usually discreet—sometimes to the point of being difficult to see with the naked eye—but “builds up” on the sensor during a long exposure; [see “A Guide to Low-level Landscape Lighting"]
low-light image · a photograph created in relatively minimal light, such as under a night sky
low pressure sodium vapor light · a type of gas-discharge light source that can appear intensely yellow or orange in night photography, which is often deemed as unfavorable and difficult to fix in post-production; [see photo]
lumens · a standard measurement of the amount light produced by a light source
luminance noise · image noise in the form of variations of brightness in adjacent pixels or groups of pixels, most often caused by photographing at high ISOs or by brightening an underexposed photograph in post-production; appears as “grain” in a digital image; [see photo]
lunar corona · a faint disc or small rings of light around the moon created by moonlight refracting through thin clouds
lunar eclipse · an astronomical phenomenon wherein the Earth fully or partially blocks sunlight from reaching the moon as seen from a point on Earth; [see photo]
lunar halo · a circle around the moon created by moonlight refracting in ice crystals in the atmosphere; [see photo]
lunar pillar · see “moon pillar”
M
macro lens · a specialized camera lens that is able to be focused on a subject close enough to achieve at least a 1-to-1 representation of the subject on the camera sensor
March equinox · an equinox that occurs in March; also known as “spring equinox” or “vernal equinox” in the Northern Hemisphere and “autumnal equinox” in the Southern Hemisphere
Magellanic Clouds · composed of the Large Magellanic Cloud and the Small Magellanic Cloud, two dwarf galaxies (both satellites of the Milky Way) that are visible in the Southern Hemisphere and as far north as about 17 degrees latitude in the Northern Hemisphere; [see photo]
mercury vapor light · a type of gas-discharge light source that uses vaporized mercury; tends to produce a cyan or green color cast in night photographs, depending on the white balance used during exposure or processing; [see photo]
metadata · data about a photograph that is embedded in the digital image file; for example, exposure, camera and lens info, copyright line, GPS coordinates, etc.
metal halide light · a type of light source that uses vaporized mercury and metal halides; tends to produce a blue or green color in night photography; [see photo]
meteor · a meteoroid that has entered Earth’s atmosphere, combusting in a way that often emits a brief trail of light; also known as a “shooting star”; [see photo]
meteor shower · a celestial event in which multiple meteoroids from the same cloud of space debris enter Earth’s atmosphere, resulting in numerous visible streaks in the night sky during a period of days or weeks; [see “How to Photograph a Meteor Shower"]
meteor shower peak · the night or nights when a meteor shower produces its maximum number of visible meteors
meteor storm · a period of high activity in a meteor shower, generally defined as more than 1,000 meteors per hour; also known as an “outburst”
meteor shower radiant · 1. the point in the sky where meteors in a shower appear to originate from or trace back to; 2. an image created by photographing many star-point exposures of a meteor shower, layering the images in post-production, then rotating the layered frames to compensate for the Earth’s rotation; results in an image depicting multiple meteor trails emanating from the shower’s radiant displayed at a fixed point in time; [see “How to Process a Meteor Shower Radiant”]; [see photo]
Milky Schmear · see “Silky Way”
Milky Way · 1. the galaxy that includes Earth, its solar system and hundreds of billions of other stars; 2. though all but a few celestial objects visible with the naked eye are in the Milky Way galaxy, the band of dense stars that stretches from horizon to horizon is commonly referred to as “the Milky Way”; [see photo]
Milky Way blend · a processing technique for combining a Milky Way sky with a foreground photographed in a way to reveal detail in the landscape—such as with a longer exposure or at blue hour when more light is available—to create a final image with foreground detail in front of a Milky Way sky; [see photo]
Milky Way pano · a stitched panorama photograph that depicts the Milky Way, usually with the Milky Way arching (due to a distortion effect that is natural to the technique) across the frame; [see “How to Plan, Shoot and Edit a Milky Way Arch Panorama”]; [see photo]
Milky Way season · the months of the year when the Milky Way galactic core can be seen and photographed at “reasonable” hours of the night; generally considered to be April to October in the Northern Hemisphere, and March to October in the Southern Hemisphere
mirrorless camera · an interchangeable lens camera that differs from a DSLR in that it is designed with no mirror and pentaprism, with a digital viewfinder for previewing and reviewing images
mixed light · two or more different types of light sources in the same scene; could be different color temperatures, different bulb types, etc.; for example, LED streetlamps, high-pressure sodium flood lights and neon window signs all in the same scene; [see photo]
moiré · an undesirable artifact in digital photographs wherein misaligned pixels create a subtle but noticeable wavy or banded pattern that appears to lay over the image; traditionally seen in portraits featuring highly detailed patterns in clothing fabric, but in night photography is sometimes seen in stacked images; [see photo]
motorized mount · see “tracking mount”
moonbow · a rainbow created by moonlight rather than sunlight; occurs when moonlight directly illuminates water vapor, such as fog or waterfall mist; uncommon, and usually seen only in a photograph as opposed to with the naked eye
moonburst · a starburst effect created around the moon by photographing it with a small aperture; [see photo]
moonlight · sunlight that reflects off the moon onto the surface of the Earth
moon phase · one of eight defined transition periods in the lunar cycle, categorized as “primary phases” (new, first quarter, full, last quarter) and “intermediate phases” (waxing crescent, waxing gibbous, waning gibbous, waning crescent); in chronological order the phases are new (0 percent illumination), waxing crescent (0.1 to 49.9 percent), first quarter (50 percent), waxing gibbous (50.1 to 99.9 percent), full (100 percent), waning gibbous (99.9 to 50.1 percent), last quarter (50 percent), waning crescent (49.9 to 0.1 percent)
moon pillar · a vertical shaft of light extending from the horizon during twilight or nighttime, caused by moonlight radiating from below the horizon before moonrise or after moonset and reflecting off high-altitude ice crystals; also known as a “lunar pillar”
moonlight blend · a processing technique for combining a foreground photographed under moonlight with a sky photographed in darkness at another time of the night (i.e., before the moon rose or after it set) to create a final image with foreground detail in front of a starry sky; also known as a “twilight blend” [see photo]
moonrise · the time and event of the moon appearing to rise from the horizon as the Earth rotates
moonset · the time and event of the moon appearing to set beneath the horizon as the Earth rotates
moonscape · a nighttime photograph wherein the landscape is illuminated by moonlight; [see photo]
moon trail · a trail of light in a photograph created by the moon moving through the sky during a long exposure; [see photo]
N
native ISO · a camera’s baseline ISO—the ISO value for which a given camera does not need to employ any algorithmic processing to compensate in order to mimic a higher or lower setting
nautical twilight · the middle of three stages of twilight, when the sun is about 12 degrees below the horizon; [also see “civil twilight” and “astronomical twilight"]
neutral density filter · a filter that reduces the amount of light passing through it while only minimally affecting color or color temperature; [see photo]
new moon · the first of the primary phases of the moon, occurring between last quarter and first quarter, with an illumination of 0 percent; see “moon phase”
night photography · a genre of photography practiced at night in low-light conditions
night portraiture · creating portraits in low-light, nighttime conditions; [see “How To Create Stellar Night Portraits"]
nightscape · a landscape photograph made at night under dark-sky conditions
night sky festival · see “dark sky festival”
noise blend · a processing technique for combining two (or more) parts of an image that are processed differently for noise reduction, such as a foreground landscape and a background sky that require different noise mitigation
noise stacking · a processing technique for reducing apparent high ISO noise by analyzing multiple exposures of the same scene in noise-reduction software
normal lens · a lens that captures a scene with a field of view relatively close to what an average person sees with their eyes; for a camera with a full-frame sensor, about 50mm
North Star · see “Polaris”
northern lights · auroras seen in the Northern Hemisphere; also known as “aurora australis”; see “aurora”
NPF Rule · a complex algorithm for precisely determining the maximum shutter speed for a given camera and lens combination that will result in stars that appear as points in a photograph; [see “New Rule for Shooting the Sharpest Stars in the Sky"]
O
outburst · see “meteor storm”
overexpose · to allow too much light in an exposure, resulting in an image that is brighter than desired
overlit · a photograph for which too much light was added to the scene, determined either by overexposure or by aesthetic judgment
overprocess · a term (largely pejorative) indicating that a photographer has applied too many adjustments in post-production, resulting in a final image that is unsatisfactory
P
panel light · an often square or rectangular panel mounted with arrays of LEDs that combine to create a strong enough light source to use for photography; often the tool of choice for Low-level Light Painting, due to its capacity to be turned on at very low levels of illumination; [see photo]
panorama or pano · though the term in its basic form indicates any photograph in a non-standard wide format, it’s most commonly used to describe a technique wherein the photographer exposes multiple frames while rotating the camera horizontally across a scene, then “stitches” those frames together in post-production to create one high-resolution image that is wider and more detailed than could be created with a single frame in the same camera; [see photo]
pan-tilt head · a tripod head with right-to-left and up-and-down controls that are independent of one another; allows for more precise positioning of the head and camera; [see photo]
Photographer’s Ephemeris, The (TPE) · an app regarded as the that effectively enabled a photographer to determine the time and location of astronomical events, such as sunset and moonrise
PhotoPills · a ubiquitous app that provides a photographer with a wide range of information for scouting and executing photographs either of or that rely on astronomical events, such as sunrises, moonsets, Milky Way, meteor showers, etc.
Photoshop · the industry-standard software made by Adobe most useful today for making advanced edits of digital photographs
photosite · a single photosensitive “cell” on a camera sensor that creates a single pixel in a digital image
pixel-peeping · a (largely pejorative) term for looking at a photograph at the pixel level (generally to search for flaws) rather than from a “normal” viewing distance (to enjoy the art of the photograph)
plane trail · a light streak in a night photo caused by the lights of a plane flying through the scene during a long exposure; [see photo]
planisphere · a handheld star chart for identifying celestial objects in the field
Pleiades, The · a dense cluster of stars visible with the naked eye from every major landmass on Earth except Antarctica; also known as The Seven Sisters
Polaris · a star in the asterism of the Little Dipper (within the constellation of Ursa Minor) that appears to stay stationary in the night sky as the Earth rotates, and therefore has been a historically reliable indicator or north; also known as the “North Star”
polarizer filter · a filter that prevents certain waves of light from entering a camera lens, used primarily for reducing reflections and darkening skies; [see “Why You Should Use a Circular Polarizer at Night"]
post-production · the stage of image creation after the raw data has been captured in the field and the image is processed in editing software or a darkroom
ppi or pixels per inch · a measure for the number of pixels in one linear inch of a camera sensor or digital photograph; often erroneously referred to as “dpi”
primary moon phase · one of four major moon phases: new, first quarter, full and last quarter; each occurs between an intermediate moon phase; see “moon phase”
processing · altering a photograph after it has been recorded in the field, either with digital editing tools or in a traditional darkroom
Q
quick-release · a type of tripod head that attaches to a plate that is screwed onto the bottom of a camera or lens, allowing photo gear to be put on and taken off the tripod more rapidly
quarter moon · a primary phase of the moon that occurs between new moon and full moon, as either “first quarter” or “last quarter,” with an illumination of 25 percent; sometimes referred to as a “half moon,” though that moniker is merely descriptive, and is neither official nor astronomically accurate
R
reflected light · light that directly hits an object/surface and reflects onto the subject
resolution · the pixel dimensions or the total pixel count of a digital image; for example, 5568 × 3712 pixels, or 20.8 megapixels
S
Sagittarius · a southerly constellation that assists in locating the Milky Way core; also known as “The Archer”
self-timer · a mechanism—either in-camera or an external device—used to delay a shutter opening for a predetermined amount time
Sequator · a PC-based software application that enables a photographer to stack multiple frames of astro-landscape images to reduce visual noise in the final image
September equinox · an equinox that occurs in September; also known as “autumnal equinox” in the Northern Hemisphere and “spring equinox” in the Southern Hemisphere
shadow painting · 1. a light-painting mindset of visualizing and deciding which parts of a scene should remain in shadow, as opposed to thinking only about what should be lit; 2. light painting that results in the shadow of a subject in the composition, for example, a shadow of a tree on rock face
shooting star · see “meteor”
sidelight · light that hits the subject from the side (from the camera’s perspective); [see photo]
signal-to-noise ratio · in digital photography, a comparison of the visual data that a sensor receives with the quality of the visual data the camera records; a high ratio (usually caused by photographing at a high ISO) leads to more color or luminance noise
Silky Way · a “blurred” Milky Way created by photographing the galactic core with a shutter speed long enough to create noticeable star trails; also known as a “Milky Schmear”; [see photo]
Simmer Dim · at northerly and southerly latitudes (higher than 47 degrees), a phenomenon wherein twilight can last for hours; [see “Photographing in Twilight that Lasts Till Morning"]
Six-Stop Rule · a high ISO test formula for quickly determining a long, low ISO exposure based on a successful, shorter, test exposure made at ISO 6400; expressed as shutter speed in seconds at ISO 6400 = shutter speed in minutes at ISO 100
skyglow · a glow in the night sky caused by light pollution; “airglow” is a similar effect, albeit with natural causes; [see photo]
Small Magellanic Cloud · see “Magellanic Clouds”
sodium vapor light · a type of gas-discharge light source that can cause color shifts in night photography that can be deemed as unfavorable; see “high pressure sodium vapor light” and “low pressure sodium vapor light”; [see photo]
solar eclipse · an astronomical phenomenon wherein the moon fully or partially blocks sunlight from reaching a point on Earth; [see photo]
solar maximum · the period of the highest solar activity during the 11-year solar cycle, resulting in an increased frequency of sunspots, solar flares, coronal mass ejection and auroras
solar pillar · see “sun pillar”
solstice · the semiannual day or time when the sun it at its farthest distance from Earth’s north or south pole, resulting in a year’s longest duration of day or night, depending on hemisphere; individually referred to as “summer solstice” and “winter solstice,” or “June solstice” and “December solstice”
Southern Cross · an asterism (within the constellation of Crux) visible in the Southern Hemisphere that assists in locating south
southern lights · auroras seen in the Southern Hemisphere; also known as “aurora australis”; see “aurora”
speedlight · a light source that produces a quick, intense flash of illumination; also known as a “strobe” or a “flash”
spring equinox · an equinox that occurs in the spring—March in the Northern Hemisphere, September in the Southern Hemisphere; also known as “vernal equinox”
stacked image · any photograph created by layering multiple images that combine to create a single final image; for example, star stacking, focus stacking and meteor radiants
starbow · a Milky Way arch, as seen in a stitched panorama; [see photo]
starburst · a visual effect of lines, or rays, bursting from a bright light source in the frame (looking much like a star shape), created by photographing at a small aperture; [see photo]
star circles · star trails that appear as concentric circles, centered around a point above the horizon at due north (i.e., Polaris) or due south; sometimes referred to as “star rings”; [see photo]
starlight blend · a processing technique for combining a foreground photographed with a long exposure under only starlight with a sky photographed with a shorter, star-point exposure to create a final image with foreground detail in front of a starry sky; [see photo]
star-point image · a photograph created with a short enough shutter speed to depict stars as points, rather than as dashes or trails; [see photo]
Starlink · a fleet of satellites periodically launched in groups by SpaceX that can be seen and recorded in dark-sky photographs during the several nights after launch, while they are still in low Earth orbit; [see photo]
star rings · see “star circles”
star stacking · a processing technique for creating star-trail images that entails blending multiple exposures of stars moving through the sky as the Earth rotates
star tracker · see “equatorial mount”
star trails · the effect of stars appearing to streak through a night sky in a photograph due to the Earth rotating during a long exposure; [see photo]
Starry Sky Stacker · a Mac-based software application that enables an astrophotographer to stack multiple frames of deep-sky images to increase the visibility of dim celestial objects and to reduce visual noise in the final image
Starry Landscape Stacker · a Mac-based software application that enables a photographer to stack multiple frames of astro-landscape images to reduce visual noise in the final image
Steve · a ribbon- or spike-shaped aurora-like atmospheric phenomenon caused by the glow of hot plasma in the upper atmosphere; the name is an acronym for “Strong Thermal Emission Velocity Enhancement”
stitching · a processing technique that involves aligning multiple images side-by-side, overlapping common elements, so as to produce a seamless, continuous image
stop down · to decrease the amount of light passing through a lens by narrowing the aperture, for example, from f/5.6 to f/8
stops · the measurement of points where light is either halved or doubled by changing the shutter speed, aperture or ISO of an exposure
street lighting · light from streetlamps, passing cars, storefront windows, etc.; [see photo]
strobe · see “speedlight”
summer solstice · a solstice that occurs in summer, resulting in the longest day and shortest night of the year; occurs in June in the Northern Hemisphere and in December in the Southern Hemisphere; also known as “June solstice” and “December solstice”
supermoon · a full moon that comes within 90 percent of the moon’s closest distance from Earth, resulting in the moon appearing slightly larger and brighter than usual; a supermoon can also be a new moon, but has almost no effect on night photography because it can’t be seen
Super Resolution · an Adobe feature—in both Lightroom and Photoshop—that enables a photographer to quadruple the resolution of a digital photograph with minimal artifacts; [see “Adobe Brings Us High-Quality Quadruple Enlargements"]
superwide-angle lens · a wide-angle lens with a focal length that is shorter than the short side of the camera’s sensor. for example, for a full-frame camera, any lens wider than 24mm; also known as an “ultrawide-angle lens”
sun pillar · a vertical shaft of light extending from the horizon during twilight or nighttime, caused by sunlight radiating from below the horizon before sunrise or after sunset and reflecting off high-altitude ice crystals; also known as a “solar pillar”
T
targeted adjustment tool · a processing tool for clicking into a specific area of a digital image to make precise adjustments
telephoto lens · a lens with a focal length that is longer than normal, with a narrow field of view; for example, 200mm
third quarter moon · see “last quarter moon”
third-stops · the one-third and two-thirds points between full stops of exposure variables; for example, ISO 100 and 200 are full stops, and ISO 125 and 160 are the third-stops in between
time-lapse · a video created by sequentially splicing together many successive still images
Time mode or T mode · a camera setting available in most modern models that changes the function of the shutter release to open the shutter when the photographer presses the button once and then to close the shutter when the photographer presses the button again; also see “Bulb mode”
tracking mount · a camera mount that uses mechanization to move the camera during or between exposures
twilight · the period between darkness and sunrise, or between sunset and darkness; characterized by cool-temperature light; subdivided into civil twilight, nautical twilight and astronomical twilight; [see “The Importance of Twilight to the Night Photographer”]; [see photo]
twilight blend · a processing technique for combining a foreground photographed during twilight with a sky photographed in darkness to create a final image with foreground detail in front of a starry sky; also known as a “blue hour blend” [see photo]
Type 2 fun · an experience that is difficult, challenging and barely (if at all) enjoyable in the moment, but is fun to look back on and talk about; for example, staying up all night at altitude in freezing temperatures to photograph a meteor shower
U
ultrawide-angle lens · see “superwide-angle lens”
underexpose · to allow too little light in an exposure, resulting in an image that is darker than desired
underlit · a photograph for which too little light was added to the scene, determined either by underexposure or by aesthetic judgment
upsize · to increase the resolution of a digital photograph
urban ruin · also known as “urban decay” and “urbex” (urban exploration), a genre of photography, popular among night photographers, focused on subjects of abandoned and/or dilapidating human-made structures and environments; [see photo]
Ursa Major · a constellation visible year-round in the Northern Hemisphere; contains the Big Dipper asterism
V
vernal equinox · an equinox that occurs in the spring—March in the Northern Hemisphere, September in the Southern Hemisphere; also known as “spring equinox”
vertorama · though the term in its basic form may indicate any photograph in a non-standard tall format, it’s most commonly used to describe a technique wherein the photographer exposes multiple frames while tilting the camera vertically through a scene, then “stitches” those frames together in post-production to create one high-resolution image that is taller and more detailed than could be created with a single frame in the same camera; i.e., the vertical equivalent of a panorama [see photo]
W
waning crescent moon · the intermediate phase of the moon that occurs between the primary phases of last quarter and new moon; illumination transitions from 49.9 percent to 0.1 percent; see “moon phase”
waning gibbous moon · the intermediate phase of the moon that occurs between the primary phases of full moon and last quarter; illumination transitions from 99.9 percent to 50.1 percent; see “moon phase”
waxing crescent moon · the intermediate phase of the moon that occurs between the primary phases of new moon and first quarter; illumination transitions from 0.1 percent to 49.9 percent; see “moon phase”
waxing gibbous moon · the intermediate phase of the moon that occurs between the primary phases of first quarter and full moon; illumination transitions from 50.1 percent to 99.9 percent; see “moon phase”
white balance · a camera or post-production setting for adjusting how color temperature is rendered in a photograph
wide-angle lens · a lens with a focal length that is shorter than normal, with a wide field of view; for example, 14mm
winter solstice · a solstice that occurs in winter, resulting in the shortest day and longest night of the year; occurs in December in the Northern Hemisphere and in June in the Southern Hemisphere; also known as “December solstice” and “June solstice”
X
Y
Z
zodiacal light · a relatively narrow cone of milky light that can rise from the western horizon after twilight or from the eastern horizon before dawn, seen more often (but not exclusively) near tropical latitudes and close to the equinoxes; caused by sunlight reflecting off grains of dust in the inner solar system; [see photo]
