The ABC of Photography

The ABC of Photography

 

A

 Aberration

An optical fault in a lens that creates a less-than-perfect image.

In optics, the aberration is a property of optical systems, such as lenses that causes light to be spread out over some region of space rather than focused to a point. Aberrations cause the image formed by a lens to be blurred or distorted, with the nature of the distortion depending on the type of aberration.

There are six types of optical aberration:

  • Astigmatism
  • Chromatic Aberration
  • Coma
  • Distortion
  • Field Curvature
  • Spherical Aberration

Examples:

There is so much more to be researched on this specific topic!

Abstract

In photography, this term refers to images that concentrate on aspects of a subject such as shape, form, colour, and texture. Instead of a straightforward representation of a subject.

Definition of Abstract Photography.

Abstract images are conceived or imagined outside of ‘reality’. They can encompass a huge variety of subject matter, take us out of our comfort zone, make us question what we see, or invite us to enter another realm. Sometimes called non-objective, experimental, conceptual or concrete photography, is a means of depicting a visual image that does not have an immediate association with the object world and that has been created through the use of photographic equipment, processes or materials.

An abstract photograph may isolate a fragment of a natural scene in order to remove its inherent context from the viewer, it may be purposely staged to create a seemingly unreal appearance from real objects, or it may involve the use of color, light, shadow, texture, shape and/or form to convey a feeling, sensation or impression. The image may be produced using traditional photographic equipment like a camera, darkroom or computer, or it may be created without using a camera by directly manipulating film, paper or other photographic media, including digital presentations.

Adjustment layer

This is a layer containing an image adjustment or effect instead of image content. Like a red Cellophane overlay on a print, an adjustment layer will alter the appearance of layers below it, but not actually alter their content, making adjustment layers a cornerstone of reversible, ‘non-destructive’ editing. The adjustment can be altered, hidden or removed at any point. When you add an adjustment layer, a mask is also automatically created, so that the effect can be applied to a lesser extent (or not at all) in particular areas of the image. The Adjustment Layers in Photoshop are a group of super useful, non-destructive image editing tools that add color and tonal adjustments to your image without permanently changing its pixels. With the adjustment layers, you can edit and discard your adjustments or restore your original image at any time.

 Adobe Camera Raw

A free plugin used by Photoshop and Elements to process and edit raw files. Adobe Camera Raw is frequently updated to support the newest camera models.  Adobe Camera Raw, which lets you import and enhance raw images, has been a must-have tool for professional photographers right since it was first released in 2003. Applications that support Adobe Camera Raw include Photoshop, Photoshop Elements, After Effects, and Bridge. Additionally, Adobe Lightroom is built upon the same powerful raw image processing technology that powers Adobe Camera Raw.

AE

An abbreviation for automatic exposure. This camera feature enables the user to determine the shutter speed and aperture for an image, usually via a TTL (through-the-lens) exposure meter. Automatic exposure mode (also called automatic exposure and abbreviated as AE) is a standard feature on digital cameras that will automatically determine the correct exposure for pictures without any user input other than to select the AE option before taking a picture.

 AEL

Automatic exposure lock. This is a push-button control that enables you to select the part of the scene from which the camera takes its meter reading, and then lock this setting while the image is re-framed for better composition. The auto-exposure lock (AE-L) function on a DSLR camera lets you physically lock the exposure reading from anywhere in the scene. You can use it on its own or at the point where you focus the image. Just about all DSLR cameras have an auto exposure lock button.

 AF

Stands for autofocus, a function first introduced on cameras in the late 1970s, in which the lens is adjusted automatically to bring the designated part of the image into sharp focus. Almost all modern lenses for digital SLRs have AF, which is achieved via one or more sensors and a motor either integrated into the lens itself or the camera body.

An autofocus (or AF) optical system uses a sensor, a control system, and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication. Autofocus methods are distinguished by their type as being either active, passive or hybrid variants.

Autofocus systems rely on one or more sensors to determine the correct focus. Some AF systems rely on a single sensor, while others use an array of sensors. Most modern SLR cameras use through the lens optical sensors, with a separate sensor array providing light metering, although the latter can be programmed to prioritize its metering to the same area as one or more of the AF sensors.

Through-the-lens optical autofocusing is now often speedier and more precise than can be achieved manually with an ordinary viewfinder, although more precise manual focus can be achieved with special accessories such as focusing magnifiers. Autofocus accuracy within 1/3 of the depth of field (DOF) at the widest aperture of the lens is common in professional AF SLR cameras.

AF illuminator

This is a system used by some cameras and flashguns to assist autofocus in low light. A pattern of red light is projected on to the subject, which aids the contrast-detection autofocus to adjust the lens correctly.

 AF-S

This stands for ‘autofocus-silent’, and refers to Nikon lenses that use a silent motor to control the autofocus system.

AL

See the aspherical lens.

Albumen print

A type of photographic print invented in 1850 by Frenchman Louis Désiré Blanquart-Evrard (1802-1872). It consists of a sheet of paper coated in egg white (albumen) and salt, then dipped in a light-sensitive silver nitrate solution. The paper, when dried, is overlaid with a glass negative and exposed to the sun. The albumen print was widely used until the late 19th century.

 Alternative processes

This term refers to a range of photographic processes, mostly dating from the late 19th and early 20th century, which devotees continue to use for their unique qualities. They include the daguerreotype, gum bichromate, cyanotype, salt print, bromoil, platinum, and palladian processes.

Ambient light

The existing light in a particular scene, which may be sunlight, moonlight or an artificial light already providing illumination. It excludes any light source added by the photographer, such as flash or studio lighting.

Angle of view

A measurement of how much a lens can see of a scene from a particular position, usually measured in degrees. The longer the focal length of the lens, the narrower the angle of view. Zoom lenses have adjustable angles of view.

Antialiasing

A method of smoothing diagonal or curved lines in digital images to avoid a ‘staircase’ or ‘stepped’ appearance (also called ‘jaggies’), caused by the fact that the pixels making up an image are discrete blocks of colour.

Aperture

The opening in the lens that restricts how much light reaches the image sensor. In all but the most basic cameras, the size of the aperture is adjustable. The aperture setting used has an important role to play in both exposure and depth of field.

 Aperture priority

Semi-automatic exposure system, where the aperture is set by the photographer. The shutter speed is then set by the camera to suit the light level reading taken by the camera’s own meter.

APO

Abbreviation of apochromatic. This is used to describe Sigma lenses that use super-low dispersion (SLD) lens elements to reduce chromatic aberration.

APS

The initials of the Advanced Photo System, a short-lived film photography format introduced by Kodak and other manufacturers in 1996. The 24mm film was housed in a drop-in cartridge and could be shot in three different formats. It was mainly used in compact cameras, but also a small number of SLRs.

APS-C

This refers to the size of the sensor used in some digital cameras, measuring around 22.5x15mm, and with a 3:2 aspect ratio. It gets its name and dimensions from the APS (Advanced Photo System) Film format, used in its Classic (C) aspect ratio.

Artifacts

Flaws in an image caused by limitations in the recording or manipulation process. Examples include colour and tonal banding, random blotches or a mottled, grainy appearance.

ASA

A method of measuring and specifying film speed, or a film’s sensitivity to light, as devised by the American Standards Association in 1943. It was replaced by the ISO (International Organisation for Standardisation) film speed system in the 1980s. Also, see ISO.

AS and Asp

Abbreviations for a-spherical. See a-spherical lens.

Aspect ratio

The relationship between the width and height of a picture, which describes the proportions of an image format or a photograph. The aspect ratio of most D-SLRs is 3:2, while on most other digital cameras, it’s 4:3.

A-spherical lens

A lens element that has a surface that isn’t perfectly spherical. All camera lenses are made up of a number of individual lenses or elements. Many of these elements are spherical as if cut from a sphere. A-spherical elements are less rounded and are used in wide-angle and wide-aperture lenses to help provide distortion-free images.

Astrophotography

Photography achieved by attaching a camera to a telescope and concerned with recording images of astronomical objects in the night sky such as stars, planets and the moon. Astrophotography can also be used to record astronomical objects invisible to the human eye by using long exposures.

AT-X

Stands for Advanced Technology Extra – the branding used on all current Tokina lenses.

Auto-bracketing

A feature on some cameras that enables you to automatically shoot a sequence of shots of the same scene at slightly different shutter speeds (or aperture settings) from the ‘correct exposure’. This feature can be used if there’s some doubt that the meter reading is accurate for a particular subject. It can also be used to shoot a sequence that’s combined into one high dynamic range image. See HDR. Other auto-bracketing features available on some cameras include automatic flash, ISO or white balance bracketing.

Autochrome

The name of the first colour photography process, invented by French brothers Auguste and Louis Lumière, and patented in 1903. A glass plate was coated in microscopic grains of potato starch, coloured red, green and blue, overlaid with a black-and-white silver halide emulsion. The process was widely used until Kodachrome and Agfacolor films were introduced in the 1930s.

Autofocus

See AF.

Available light

See ambient light.

Avedon, Richard

Avedon (1923-2004) was one of America’s most famous fashion and portrait photographers. He was the chief photographer for Harper’s Bazaar magazine in the 1940s and Vogue from the 1960s. His portraits are famous for their intimacy as well as their stark and minimalist quality.

AWB

Automatic white balance. This is a system that automatically adjusts the colour balance of an image, according to the colour temperature of the light source, to make it look as natural as possible to the human eye.

  

                           B

 B (Bulb)

The Bulb setting (abbreviated B) on camera shutters is a momentary-action mode that holds shutters open for as long as a photographer depresses the shutter-release button. The Bulb setting is distinct from the shutter’s Time(T) setting, which is an alternate-action mode where the shutter opens when the shutter-release button is pressed and released once and closes when the button is actuated again.

The bulb setting is used on some cameras, including some point-and-shoot cameras, to obtain shutter speeds slower than the minimum offered by the camera otherwise.

Because of the risk of camera movement, the camera is most often mounted on a tripod for the duration of the exposure. While it is generally possible to use the shutter release button on the camera itself, a cable release or electronic remote is often used to further eliminate the risk of shaking the camera during long exposures. The cable releases generally include a locking feature to eliminate the need to keep the button or plunger depressed during extremely long exposures.

The bulb setting is useful for the following types of photographic subjects:

  • fireworks at night
  • the night sky and celestial objects (see astrophotography)
  • lightning
  • streets at night (creating streaks from moving cars)
  • light painting

Backlighting

An image is backlit when the light source is on the far side of the subject in relation to the camera. It means that there’s more light coming from behind the subject than is directly on the subject itself. It’s often used to separate the subject from the background to make a subject more dramatic, or to make a silhouette.

In photography, a backlight (often the sun) that is about sixteen times more intense than the key light produces a silhouette. A fill flash used with a backlit subject yields more even lighting.

The vertical angle of the backlight can change the effect. A low angle can make the light hit the camera lens, causing a lens flare. A high angle can make the subject’s nose extend out from the mostly vertical shadow of the head, producing a potentially unwanted highlight in the middle of the face.

 Backup

A copy of a digital file that’s kept in case of damage to, or loss of, the original digital image.

 Ball head

A type of tripod head in which the head mount, which holds the camera, is attached to a ball-and-socket joint. When the socket is tightened using the ball lock knob, it locks the head in place.

Barn doors

Four hinged doors fixed on the front of studio lights. The doors are used to modify the shape and the direction of the light.

 Barrel distortion

Barrel distortion is a lens fault or aberration that causes straight, parallel lines in an image to bow outward, and is seen when shooting with wide-angle lenses. The wider the lens, the greater the distortion. The appearance is similar to the effect you’d see if an image was wrapped around a barrel.

It can be corrected using post-capture software.

Beauty dish

A studio lighting device used to give a flattering effect in portrait and fashion photography. It consists of a large circular dish-shaped reflector, usually around 40-50cm in diameter, with a light source in the center. The light usually has an opaque cover so that only the diffused light reflected from the dish reaches the subject.

Beauty Dish example:

The difference when using:

 Bellows

A concertinaed tube made of flexible, light-proof material that separates a lens from the camera body. Bellows were first used on very early cameras in the mid-19th century, and are still used on large-format equipment (such as the Ebony view cameras) today. They allow the plane of focus to be adjusted via a swing and tilt mechanism. Bellows are also used instead of extension rings on SLR cameras for making more finely adjustable macro images.

Bit

The basic unit from which any digital piece of data is made. Each bit has a value of either 0 or 1. The sizes of digital files are usually counted in bytes, which are each made up of eight bits.

 Bit depth

The number of bits used to record the colour of a single pixel. Digital cameras usually use at least eight bits for each of the red, green, and blue channels, providing a 24-bit depth, and possible 16,700,000 colours. Many D-SLRs offer higher bit depths when setting to record in raw mode.

 Blending mode

Blending modes determine how the pixels in a layer interact with the underlying pixels on other layers instead of simply covering them. Some blending modes are much more useful for photo editing than others. Multiply is used to darken an image, and Screen to lighten it; Overlay and Soft Light boost contrast.

 Blown out

Bright areas in a photo that are over-exposed are said to be blown out. They won’t hold any detail and will be bleached white.

 Bokeh

Derived from the Japanese word for ‘blur’, this term is used to describe the aesthetic quality of the blur in out-of-focus areas of a picture, or the lens creating them. Smooth, circular out-of-focus highlights are a feature of ‘good bokeh.’

Bounce flash

The indirect flash-lighting technique, where the flashgun is angled to bounce off a wall, ceiling, or another reflector. This scatters the illumination, creating a softer lighting effect.

 Bounding box

In Photoshop, a rectangular border around a selected part of an image that can be dragged to transform, rotate, scale or move.

 Bracketing

A system for increasing the chances of getting the correct exposure by taking a sequence of

pictures with a slightly different exposure setting for each.

 Bridge camera

A camera that bridges the gap between compacts and D-SLRs. They are similar in appearance and handling to small D-SLRs, but they have a fixed, usually ‘super zoom’ lens, with some models offering up to 50x optical zoom. Instead of a D-SLR’s optical viewfinder, they have an electronic viewfinder.

 Brightness range

This is the difference between the brightness of the brightest part of the subject and the brightness of the darkest part of the subject. Also known as Subject Brightness Range (SBR).

Buffer

Temporary memory used by a digital SLR. The size of the buffer in a camera helps dictate the maximum burst rate and the number of shots per burst.

 Burn tool

A tool that can be used to darken parts of an image selectively during digital image manipulation. The tool gets its name (and its hand-shaped icon) from ‘burning- in’, a traditional darkroom process in which parts of a print could be made darker by giving some areas of a print more exposure than others. Also, see Dodge tool.

Burst rate

The continuous shooting speed of a digital camera, which enables a sequence of images to be taken in rapid succession, measured in frames per second (fps). The rate can only be sustained for a certain number of shots.

 Butterfly lighting

A technique for lighting portraits achieved by pointing the flash down towards the front of the face and creating a distinctive butterfly-shaped shadow under the nose. A reflector is used to soften the shadow. This technique is also known as ‘Paramount lighting’ after the movie studio’s glamorous portraits from the 1930s.

Byte

The standard unit for measuring the memory capacity of digital storage devices. Each byte can have one of 256 different values, and is equal to eight bits.

C

Cable release

A mechanical or electronic device for firing a camera from a short distance away, without physically pressing the shutter release. It’s often used as a way to minimize vibration when using a slow shutter speed and camera support, such as a tripod.

 Calibrator

A device used to standardize the colour and brightness of a computer monitor so that images can be accurately adjusted.

 Calotype

One of the earliest photographic processes, announced by William Henry Fox Talbot (1800-1877) in 1841, in which a negative image was recorded on a sheet of translucent paper coated with light-sensitive chemicals. The earliest surviving example is an image of a window at Lacock Abbey, made in 1835. Using the process, multiple positive images could subsequently be produced by contact-printing the negative.

 Camera shake

Blurring of the image caused by

movement of the camera during

the exposure. Handheld cameras

are prone to camera shake, and the

fastest available shutter speed

needs to be used to reduce or

eliminate the problem.

 Camera trap

A remotely activated camera used

for documenting the behavior of animals

in the wild without the photographer being present.

The camera’s shutter is usually triggered

when an animal’s movement is detected by an

infrared or motion sensor. Cameron, Julia Margaret

Julia Margaret Cameron (1815-1879) was a

British photographer who made portraits

of some of the major figures of the Victorian

period as well as her relatives and

friends. She was one of the first

people to see photography as an

artistic medium open to interpretation,

rather than simply a mechanical process

for recording reality. Her portraits often make a

creative use of soft focus.

Cartridge film

A type of photographic film housed

in a plastic cassette. Because it’s

light-tight, film can be loaded into

a camera in daylight. 126 cartridge

film was introduced by Kodak in

1963, followed by 110 film in 1972.

Two later formats, Disc film and

APS film, used their own specially

designed cartridges. 

Catchlight

A white highlight in the eye of the

subject, which is a reflection of the

light source. The shape, size and

intensity of the highlight, as well as

the number of highlights, will vary

depending on the lighting setup. 

Centre-weighted

A type of built-in metering system,

provided as an option on some

cameras. Centre-weighted meters

measure light intensity across the

entire image area, but bias the

average in favor of light taken

toward the center of the frame. The

system isn’t foolproof; it’s easier to

predict when it will make an

inappropriate reading than more

sophisticated metering systems.

 Channel mixer

A feature in Photoshop that

enables you to adjust the red, green

and blue channels to increase or

decrease colour saturation, or

convert an image to monochrome.

 Chiaroscuro

A term that originated in

Renaissance art. It refers to a style

of image that features a strong

contrast between the light and dark

areas of the picture.

 Chimping

This is a short form of ‘checking

image preview’. It refers to the act

of looking too frequently at the

image on your camera’s LCD

screen, rather than concentrating

on the subject.

 Chromatic aberration

A lens fault common in telephoto

lenses in which different colours of

white light are focused at slightly

different distances, creating ugly

coloured haloes around the edges

of a photographic subject. Software

can remove or reduce the effect.

Chromogenic film

A fine-grain photographic film

that produces black-and-white

images, but is processed using C41

colour chemistry.

Circular polarizer

A type of polarizing filter. Circular

polarizers can be used with modern

cameras without interfering with

the operation of exposure metering

and autofocus systems, unlike

older and cheaper linear polarizers.

Clipping

Clipping occurs when the dark

parts of an image become pure

black or the light parts become

pure white, so that image detail is

lost in these areas. On a histogram,

a clipped shadow or highlight is

indicated by the graph being ‘cut

off’ on the left-hand (shadows) or

right-hand (highlights) side.

Clone Stamp

An image-editing tool that enables

you to replace an area of the image

with pixels taken from elsewhere in

the image (or even another image).

It’s commonly used for removing

blemishes and other unwanted

objects from a picture.

Close-up lens

A filter-like accessory that fits on

the front of the camera lens to

magnify the image. This low-cost

macro accessory can be used on

most types of cameras and lenses.

Close-up lenses come in a variety

of different strengths, usually

measured in dioptres. CMOS

(Complementary Metal Oxide Semiconductor)

This is a type of imaging sensor

used in digital cameras. Located at

the focal plane, it converts the

focused image into an electrical

signal. It’s similar in function to

the CCD sensor.

CMYK

Cyan, magenta, yellow and black

(or ‘key’), the four primary inks

used in commercial colour

printing. CMYK also refers to the

printing process itself.

Collodion process

This is an early technique for

making photographic prints,

invented by Frederick Scott Archer

(1813-1857) in 1851, which used

collodion (cellulose nitrate) to stick

light-sensitive chemicals on the

surface of a glass plate. The plate

was exposed, developed and fixed

while still wet. The process

produced good results and was

used widely until around 1880.

Colour cast

A colour tint in an image, caused

by shooting in a particular kind of

light. Tungsten light causes a

yellow cast, while fluorescent light

causes a green cast. Casts can be

corrected using the camera’s white

balance feature, or at the post-

capture stage.

 Colour channels

Every colour you see on a screen is

created by a specific mix of red,

green and blue light, and every

printed colour by a specific

formula of ink colours. In

can be represented and seen as

separate colour channels – RGB for

most digital photos. See Channel

mixer for more on this.

Colour filter array (CFA)

The pattern for red, green, and blue

filters used over the photo sites in

an imaging sensor. Usually, half the

photo sites in a digital camera

(which define pixels) have green

filters, a quarter have red filters,

and quarter have blue filters.

Colour management

An overall system that tries to

ensure that the colours of an image

are displayed and output in exactly

the same way, whatever the device

being used.

Colour profile

Description of how a camera,

printer, monitor or other device

displays or records colour. It

provides a universal way in which

different devices can produce

similar-looking results. This is

sometimes known as an ICC

profile, because the standards are

set down by the ICC (International

Colour Consortium).

Colour negative film

Film on which all original colours

are recorded as their

complementary colours. When the

image is printed on photographic

paper, the colours are again

reversed to their original hue.

Colour negatives have an orange

tint or mask, which helps to

control contrast and improves the

reproduction quality.

Colour reversal film

Film processed to produce a colour

positive image on its transparent

base. Traditionally, images are

mounted in card or plastic mounts.

Also commonly known as slide or

transparency film.

Colour space

The theoretical definition of the

range of colours that can be

displayed by a device.

Colour temperature

All light sources have a

characteristic colour temperature:

artificial (tungsten-filament) lights

are warmer (more orange) than

daylight, which is warm near dawn,

turns cooler (more blue) during the

day, then warms again at nightfall.

Our eyes adjust for colour

temperature much of the time

without our realizing it, so that

colours look pretty consistent.

Digital cameras can make

electronic adjustments using a

white balance system to neutralize

colours. When they get it wrong

(or you use the wrong white

balance setting on your camera),

a colour cast results.

Combination printing

The use of two or more negatives

to make one print. The technique

was first used in the mid-19th

century to overcome exposure

limitations in early photographic

processes, although photographers

such as Oscar Gustave Rejlander

(1813-1875) could use dozens of

images to make one epic scene.

Compact

A type of camera with a shutter

mechanism built into the lens.

Compacts are generally point-and-

shoot designs that are easy to carry

around. Most digital compacts have

built-in zoom lenses.

Complementary colours

Also known as ‘opposite colours’,

these are pairs of colours that

create a strong contrast. On the

traditional colour wheel they are

red/green, yellow/violet and blue/

orange, while the CMYK and RGB

models use red/cyan, green/

magenta and blue/yellow.

Compression

The process of reducing the sizes

of files such as digital images, so

that they use less storage capacity

and are faster to upload and

download. See lossless compression

and lossy compression.

Contact print/sheet

Contact prints are photographic

images made by laying one or more

film negatives on a sheet of

photographic paper, usually under

a sheet of glass, and exposing it to

light. In the traditional wet

darkroom, a contact sheet is

usually the first stage of printing

an image.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

The ABC of Photography –

Continuous autofocus

This is an autofocus setting in

which the focus is constantly

adjusted until the shutter is

actually fired. It’s especially useful

for moving subjects such as in

wildlife or sports photography,

where it would be unhelpful for the

focus distance to be locked as soon

as it’s initially found.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

 

 

 

 

The ABC of Photography –

Continuous lighting

Lighting that remains on

throughout a shoot, as opposed to

the brief burst of illumination

given by flash or strobe lighting.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The ABC of Photography –

Contrast range

A measurement of the difference

in brightness between the very

darkest and lightest parts of an

image. See brightness range.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

 

 

 

 

 

 

The ABC of Photography –

Converging verticals

A term used to describe the effect

of parallel lines getting closer

together, particularly the two sides

of a building, or a section of a

building, when shooting from a low

angle of view.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

The ABC of Photography –

Crop

To remove unwanted parts of

an image.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

The ABC of Photography –

Crop factor

Sensors of several different sizes

are used in D-SLRs, and this size

affects the angle of view offered by

a particular lens. The smaller the

sensor, the narrower the angle of

view. The ‘crop factor’ is to convert

the actual focal length of a lens to

the effective focal length (EFL –

see below). The crop factor for Four

Thirds and Micro Four Thirds

models is 2x; the crop factor for

most popular D-SLRs is 1.5x or

1.6x. Full-frame D-SLRs need no

focal length conversion, so they

have a crop factor of 1x.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

The ABC of Photography –

Cross-processing

Sometimes called ‘X-Pro’, in film

photography this refers to

processing colour negative film in

reversal film (E6) chemicals, or

colour reversal film in negative film

(C41) chemicals. The resulting

colour shifts gave images a

distinctive look. The technique was

once especially popular in fashion

photography. A similar appearance

can be created in Photoshop by

boosting contrast and tweaking

colour channels.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School

 

 

 

 

 

 

 

The ABC of Photography –

Curves

This powerful Photoshop tool

enables you to adjust the exposure

and contrast of an image. By

altering the shape of the curve,

different areas of tone can be

lightened or darkened by varying

amounts. By altering the curves for

each of the different colour

channels, the colour balance of the

image can also be altered to create

special effects, or simply to correct

for unwanted colour casts.

Elements’ version of Curves, called

Adjust Colour Curves, is more

limited than Photoshop’s Curves.

 

D

DA

Stands for Digital Auto, which features on a range

of Pentax lenses that (unlike some earlier ranges)

don’t have a manual aperture ring. They have a ‘Quick Shift’

mechanism that enables you to override focus manually, even

when the lens is set to autofocus.

DA*

The premium lens range from Pentax, which Combines

weatherproofing with the advantages of the DA range.

Darkroom

A light-tight room for processing and printing

Traditional photographs. Negatives are loaded

into the processing tank in complete darkness,

while a red/orange safe light can be used at the

printing stage.

Daguerre, Louis

Louis Daguerre (1787-1851) was an artist and

inventor who devised one of the earliest photographic

processes, the daguerreotype, announced in 1839.

It was made by coating a silver-plated copper sheet

with light-sensitive silver iodide, and exposing it in a

camera to create a positive image.

DC

This features on the range of Sigma lenses that

are designed specifically for use with crop-factor

SLRs, and which can’t be used with full- frame models.

Decisive moment

The split-second when all the elements of a photograph

simultaneously come together. The decisive moment is

associated with Cartier-Bresson, who described

photography as “the simultaneous recognition,

in a fraction of a second, of the significance of an

event as well as of a precise organization of forms

which give that event its proper expression.”

 Dedicated flashgun

A type of flashgun that’s designed to provide direct

one-way or two-way communication with the

camera. The amount of dedication varies enormously

depending on the flashgun and camera. Increased

dedication tends to provide a more accurate flash

metering, as well as making the flash system easier to

use successfully.

Depth of field

A measure of how much of a picture is in focus, from

the nearest point in the scene to the camera

that looks sharp, to the furthermost point that looks sharp.

Depth of field is dependent on the aperture used, the

distance that the lens is focused at, and the focal

length of the lens.

 Depth of field preview

Device found on some digital SLRs that enables you to see the

viewfinder image at the actual aperture you’ll be using for the

exposure. This gives a visual indication as to how much depth of

field there is, and which parts of the resulting picture will be sharp

or blurred. This is necessary because the viewfinder normally

only shows the image as it would appear if the widest aperture

available were used.

Depth of field scale

A scale found on some lens barrels that can be used to work out the

depth of field for particular apertures, and that can be used

for manual focus adjustments to maximize or minimize the depth

of field.

Depth program

A program exposure mode in which the aperture and shutter

speed are set automatically in order to provide the maximum

depth of field, while maintaining a shutter speed that’s

fast enough for hand-held photography. With some cameras,

the different subject distances measured by the

multipoint autofocus system are also taken into account,

and the focus is adjusted to suit.

DG

This refers to the Sigma lens range suitable for full-frame SLRs (but

that can also be used on crop- factor models).

Di

Tamron’s ‘Digitally Integrated’ lenses have a full-size image circle,

so they are suitable for full-frame and crop-factor SLRs.

 Di II

Tamron’s second-generation Digitally Integrated lenses are

designed for use on popular crop-factor SLRs, and are not

suitable for full-frame models.

 Diaphragm

Another term for the aperture. These are the adjustable blades

that regulate how much light enters the lens and reaches the sensor.

 Dialog

A window that pops open when you select certain commands,

usually to give you the opportunity to configure settings or enter

further preferences. In Photoshop and Elements, menu commands

that will open a dialog for further instructions before applying their

effect are usually indicated by an ellipsis (…) after the name, such as

File>Save As… Those without this, such as File>Save, will work

immediately, with no dialog.

Differential focusing

Controlling depth of field to ensure that one element in the picture is

sharp, while others are as out of focus as possible.

 Diffraction

Scattering of light caused by deflection at the edges of an

opaque object. Diffraction causes slight fuzziness in the

image when the narrowest apertures are used.

Diffuser

Any material that scatters the light as it passes through it,

Softening the illumination and making

shadows less distinct. Diffusers are commonly used

with artificial light sources. On sunny days, clouds act

as natural diffusers.

Dioptre

Optical measurement used to describe the light-bending

Power of a lens. The dioptre value of a lens is equal to

the number of times that its focal length will

divide into 1000mm. Dioptres are used to measure the

magnification of close-up lenses, and of

viewfinder lenses.

Dioptric correction

The facility provided on some cameras for adjusting the

viewfinder to suit the user’s eyesight. Limited adjustment is

built-in and some cameras permit further modification

with the use of additional dioptre lenses.

Disc film

A short-lived format introduced by Kodak in 1982.

The disc-shaped film, housed in a plastic cartridge,

contained 15 negatives measuring 11×8 mm.

After each exposure, the disc rotated to the next frame.

Poor image quality made it unpopular,

and it was discontinued in 1999.

DNG (Digital Negative)

DNG is a raw file format invented by Adobe and used

by some camera manufacturers. An advantage of

DNG is that, unlike other raw formats, it isn’t specific

to just one camera manufacturer or model, and

it isn’t just a read-only format – you can save your files in DNG

format too. A free DNG converter application available from Adobe at

www.adobe.com/products/dng enables you to convert any raw file

into a DNG.

DO

Diffractive Optics is used on a handful of Canon telephoto lenses.

The technology enables these long lenses to be made smaller and

lighter than equivalents using conventional optical designs.

 Dodge tool

A way of lightening selected areas of the image during digital

manipulation. The tool gets its name (and its spoon-shaped icon)

from the traditional darkroom technique of ‘dodging’, where parts

of a print are shielded from exposure and therefore given less

light than other parts. See also Burn tool.

Doughnuts

The name given to the ring-shaped bokeh created by the unique

construction of a mirror lens.

DPI

Dots per inch. Strictly speaking, a measure of the density of dots of

ink that a printer lays down on paper. Compare image resolution

(density of pixels) of a print or on-screen image at a certain size,

measured in pixels per inch.

DPOF

(Digital Print Order Format) A facility available on some digital

cameras that enables users to mark the images from which they wish

to have prints made.

Duotone

A duotone image is one made from two inks (usually black and another

colour), and is often used in printed books to increase the tonal

range of an image. It’s also used by some fine-art photographers to add

subtle colour to black-and-white photographs. A similar appearance

can be achieved in Photoshop by converting a colour image to

greyscale, then choosing Image > Mode > Duotone.

DX

Tokina’s and Nikon’s way of marking lenses that are only

suitable for crop-factor (or APS-C) digital SLRs.

Dynamic range

A term used to describe the range between the lightest and darkest

points in a photograph. The range that can be recorded by a digital camera is relatively small compared with the range that the human eye

can perceive.

Sources:  Pixabay, Wikipedia, Susan Wingfield Lamar High School