Glossary For Digital Cameras
May 3, 2009
AA Cell : - This refers to the source of power, generally it is NiCd or NiMh AA size batteries.
AA Filter : - The DSLRs employ an Anti-Aliasing (AA) Filter or a Low Pass Filter (LPF) in front of their image sensors to prevent moire (wavy colours in images) problems
AC Power : - This is the mains power supply unit. In some cases digital cameras are run from the mains power supply instead of the battery. Generally requires you to buy a separate optional AC power adapter.
Add-On Lens : - Certain lenses come with filter threads on the front edge that allows you to mount a supplementary telephoto or wide angle lens system in addition to the standard lens system.
AE : - AE is the acronym for Auto Exposure. It is a system that checks the surrounding lighting conditions and automatically sets the apt exposure settings.
AE Lock : - This describes the capability of being able to lock the current exposure settings whilst pointing the camera on another subject. This task is achieved by pressing the shutter button half-way and maintaining it in that position till the next object is ready to be shot.
AF : - AF is the acronym for Auto Focus. It refers to the system that can automatically sets the camera lenses to focus on the subject.
Angle Of View : - This is calculated by the size of the image sensor and the focal length of the lens system. In compact digital cameras, it is easy to calculate the Angle of View as they generally come with fixed sensor sizes and focal length, however in DSLRs it is difficult due to its interchangeable lens systems.
Aperture : - Aperture is the opening that is formed by the iris diaphragm inside a lens.
Aperture Priority : - The aperture value determines the exposure factor. Aperture Priority is inversely proportional to the Depth Of Field, i.e. larger aperture indicates shallow DOF while a smaller aperture indicates deep DOF.
Aspect Ratio : - This is the ratio of horizontal and vertical dimensions of the image. In most of the digital cameras the aspect ratio is 4:3, for the images to aptly fit on a computer or standard TV screen. Recently, some cameras are offering 16:9 aspect ratio, for making it viewable on a high definition television.
Aspherical Lens : - These lenses have edges that are not spherical but flat for it to reproduce superior quality images.
Back-lit : - This is another term to indicate that the subject is underexposed meaning that it is heavily lit from behind. You can correct this by using critical spot metering.
Blooming : - It is the effect caused when the CCD is overexposed to a lot of light. This also known as digital overexposure may cause distortions in images.
Blue tooth : - It is a type of communication protocol that can be used to establish a wireless connection between various electronic devices.
Buffer : - It is a temporary storage area in RAM that holds data for the CPU to manipulate and transfer it into another device.
Burst Mode : - This is also known as Continuous Frame Capture and is defined as the ability to capture images as long as the shutter button is in pressed position.
CCD : - CCD is the abbreviation for Charge Coupled Device and is defined as a light sensitive chip that is used for gathering the image pattern. A colour pattern (RGB) is formed on the sensor pixels and depending on the image, the light conditions and the background, they are varied to portray the contrast and colour effects.
Chromatic Aberration : - This is also known as the purple fringe effect and is common in cameras that have long telephoto lenses. Generally occurs when a dark area is surrounded by highlight. The effect is seen as a purple line along the edge of the dark and light sections of the image. Ideally, this should not be there.
CMOS : - CMOS is the abbreviation for Complementary Metal Oxide Semiconductor. It is a type of sensor used in digital cameras. Due to its size it was generally used in DSLRs, however now some compact cameras are also using CMOS sensors.
Colour Balance : - It is the accuracy of being able to replicate the colour scheme to match the original scene.
Colour Cast : - This is any unwanted tint of a particular colour in an image, caused due to an improper amount of cyan, yellow and magenta.
Contrast : - This is defined as the measure of rate of change of the brightness factor in an image.
Dedicated Flash : - This can be defined as a type of external electronic flash that is to be used by just a particular type or series of cameras. E.g. A Canon flash cannot be used with a Nikon camera.
Densitometer : - It is an instrument that can be used to measure the quantity of light that can be reflected or transmitted by an object.
Depth of Field : - It is defined as a section of the subject that contributes to the sharpness of the image. This factor is controlled by the focal length and aperture opening of the lens.
Diffusion Dithering : - This is a method of distributing the pixels in a random pattern instead of a using a specific and predefined pattern.
Digital Image Stabilisation : - It is a method of reducing the effects of camera shakes. In this method a large frame of the image is captured and the edges are cropped depending on the direction of camera movement.
Digital Zoom : - It is type of enlargement factor wherein a a section of the image is cropped by the camera and is later magnified to fit the viewfinder portion.
Dioptre Adjustment : - In this, the optical viewfinder's enlargement factor is adapted to suit the eyesight of the user. Only a few cameras feature this facility.
DSLR : - It is type of camera; Digital Single Lens Reflex camera. Also defined as professional cameras, it comes with interchangeable lens system.
Electronic View-Finder : - They are small LCD screen that project the live view of the scene as is viewed by the sensor. The image on this display helps the camera is focusing better on the subject.
Exposure : - It is defined as the quantity of light that reaches the image sensor. It is controlled by the aperture and shutter speed of the camera.
Exposure Bracketing : - In this, the camera automatically takes around 3 to 5 shots by slightly varying the exposure value. This is done to ensure that one amongst them will be closest to the original picture.
Exposure Compensation : - In this the image is darkened or lightened by overriding the exposure settings.
F-stop : - It is a mathematical name for indicating the size of the aperture. It is inversely proportional to the opening, i.e. smaller the number larger will be the opening.
Field Of View : - All lenses come with an angle of view. The field of view is defined as the area that is covered by this angle of view.
Fill Flash : - In some situations, generally in bright sunlight, flash is not used. Images shot outdoors without flash may result in dark shadows being formed on subjects. To prevent this you can use the sill flash mode that will make use of flash in these situations, hence resulting in realistic photos.
Flash : - It is an in-built mechanism that supplies additional light to supplement the natural or available lighting conditions for better exposure, colour reproduction, and excellent image sharpness.
Focal Length : - It is defined as the distance between the image sensor and the optical centre of the lens system.
Frame : - It is defined as one of the still pictures that make up a video. The number of frames that are sent or shown per second is defined as frame rate, in any action movie the frame rate is 30 frames per second.
Gamma : - This is the measure of contrast that is found in an image. It depends on the properties of gradation curve. In case the images have very high or low contrast then Gamma correction is done. Gamma Correction is a factor that controls the overall brightness of the image.
Gradation : - It is defined as a smooth transition between two colours.
Histogram : - It is a bar graph analysis that is used to identify the contrast and dynamic range of the image. Histograms are generally found in advanced digital cameras and can be used to manipulate images.
Hot-Shoe : - It is a type of external flash connector that lets you mount the flash unit on top of the camera.
Hue : - It is a term that is used to describe the spectrum's range of colours. Hue is the element that defines the colour that is used. In gradients, when hue is used rainbow effects can be created.
Image Processing : - It a process of capturing and manipulating the image in order to enhance the quality or to extract more information from the image.
Image Resolution : - It is defined as the number of pixels per unit length of the image.
Image Sensor : - It is defined as an instrument that converts the optical signal into an electrical signal. It can be either CCD or CMOS sensor.
Image Stabilisation : - This is a technique that is used to increase the stability of an image. In this process the blur caused due to camera shakes is reduced or removed.
Interlaced : - It is defined as a technique that is used to improve the image quality without consuming extra bandwidth. In this technique the sensor first processes the odd lines and then the even lines of the image.
Interpolation : - It is a software program wherein the image can be enlarged beyond the actual resolution factor by adding extra pixels or sampling neighbouring pixels. This is with the help of complex mathematical computations. It does not add any additional information to the image.
ISO : - It is an abbreviation for International Standard Organisation is referred to indicate the light sensitivity of a sensor. Ideally, the darker the scene, higher will be the ISO that is required.
Macro : - It is used to describe the photos that are taken at close range, and refers to the lens system's ability to focus at such close distances usually less than 30cm.
Moire : - It is the pattern that occurs when more than one half-tone screens get misaligned in a colour image. It may thus result in a check-board or a rainbow pattern.
Multi-Point Focusing : - A process wherein the auto-focusing system of the camera selects more than one point to focus on.
Multi-Zone Focusing : - In this procedure, the camera determines more than one zone to focus on. This is helpful if the subject is not situated in the centre.
Noise : - In digital cameras noise occurs when high ISO is used or in low light images. It appears in the form of pixels that display random colours on the dark sections of the image.
OLED (Organic Light Emitting Diode) : - It is a recently developed display technology that is out to replace LCD. As it does not require back-light, it is considered to be more energy efficient. It also offers better contrast for the images.
Optical Image Stabilisation : - It is defined as a method that stabilises the recorded image thereby counteracting the camera movement and handshakes.
Optical Zoom : - It is defined as an enlargement factor that is obtained by moving the lens closer to the subject and then shooting the image without affecting the image quality.
Panorama : - It is the procedure of capturing a series of images and then stitching them together to form one big image that is probably not possible to shoot in a single go. It requires a unique stitching software that combines and blends the image perfectly.
Parallax : - It is an effect that is seen in close-up photography wherein the viewfinder and the lens system do not see the same image. It is in fact an apparent disorientation of an object when it is viewed along two different line of sight.
PictBridge : - It is a new standard for direct photo printing from a digital camera to any compatible printer.
Point-n-Shoot : - It is a term used to describe simple and easy to use digital cameras that come with minimum manual controls. Can also be used to refer to fully automatic cameras.
Prosumer : - It is an expensive and semi-professional digital camera that come with lots of manual functionalities.
Red-Eye : - It is the appearance of red pupils in the colour photographs. This occurs whenever the flash is situated very close to the camera lens. This can be avoided by using the red-eye correction feature provided by almost all the digital cameras.
Saturation : - It is defined as the degree to which a colour can be diluted by white light. A 100% saturated colour indicates absolutely no white light.
Shutter : - It is the device that opens and closes to let the light strike the image sensor.
Shutter Speed : - It is the time for which the sensor is exposed to external light.
Shutter Lag : - This is defined as the time gap between pressing the shutter and actually capturing the image.
Telephoto : - It is a type of lens that can magnify the image to make it appear closer.
White Balance : - It is process through which the digital cameras adjust the colour balance in order to compensate for the challenging lighting conditions or tints.
