Topic: Imaging Terminology

Aliasing

What Is Aliasing and How Does It Relate to Digital Photography? In photography aliasing is a form of distortion that occurs when two elements of the signal being processed to form a digital image become indistinguishable from one another. Aliasing often appears in an image in the form of moiré or false colouring. Many digital cameras feature a built in ‘anti-aliasing filter’ to counteract the effects of aliasing by preventing high frequencies of light from reaching the sensor. This introduces a small amount of blur to detailed areas of an image that can prevent aliasing from occurring. The image...

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Ambient Light

What Is Ambient Light and How Can It Be Used When Taking Photographs? Depending on the scene you are shooting ‘ambient light’ can be your best friend, or your worst enemy. The term ambient light refers to any natural sources of light illumination a scene i.e. any light that is not artificially created. The most obvious source of ambient light is the Sun, at sunrise and sunset it will bring a scene alive with warm tones punctuated by subtle shadows and soft detail, at high noon it will wash out your photographs with overwhelming highlights and deep impenetrable shadows. the correct timing and reading of available ambient light is key to capturing compelling lifelike photographs. Overcoming the problems that can be caused by ambient light requires extreme skill in exposure techniques, supplemental lighting and often post-processing. Also known as ‘Natural...

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Anti-Shake

What Is Anti-Shake and how Is it Used In Photography? In photography an anti-shake system compensates for unwanted movement of the camera which would otherwise blur a photograph whilst shooting, for example hand holding a camera whilst shooting in low light conditions. There are two main types of anti-shake system; Lens based anti-shake uses a moving optical element to counteract shaking. Camera based anti-shake uses a mechanism which allows the image sensor to move to compensate for unwanted movement. Anti-shake systems are also extremely popular with videographers who’s cameras do double duty as both a stills and video capture...

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Apodization Element

What Is an Apodization Element and How Is It Used When Taking Photographs? The literal definition if apodization is ‘removing the foot’, in photography terms however the term relates to the process of altering the shape of light entering a lens. In simple terms an apodization (often refered to as an APO, APD or STF lens) is a type of neutral density filter which becomes thicker towards its edges. The gradual thickening of the element limits the amount of light allowed to transition the lens progressively towards the edges of the image area. This has the effect of smoothing the...

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Bokeh

What Does Bokeh Mean When Talking About Taking Photographs? When talking about photographs the term ‘Bokeh’ refers to the quality of out of focus elements of an image. When taking a photograph you may not even think of the quality of the out of focus areas, but good bokeh, often appearing as smooth circular shaped objects in out of focus areas of an image can dramatically improve the overall feel of an picture. The Quality of the bokeh in an image is often determined by the lens used to capture the image. Lenses that use an apodization element produce...

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Color Palette

What is a Color Palette When Talking About Photography and Image Editing? Also referred to as ‘palette’ the term ‘color palette’ describes the entire range of colors that can be rendered by a digital device such as a camera LCD or a computer monitor, or the range of colors contained within a specific image. A computer monitor may have a color palette of 16 million colors, an image on the other hand often contains a much smaller number, often 256. The term is also used to describe a collection of colors, usually displayed graphically in RGB triplets, which a...

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Image Quality

What Does Image Quality Mean When Talking About Photography? When talking about photography  the term ‘image quality’ also referred to as ‘IQ’ is characteristic of an image that measures the perceived image degradation (typically, compared to an ideal or perfect image). Factors that affect quality include brightness and evenness of illumination, contrast, resolution, geometry, color fidelity and color discrimination of an observed image. Achieving the highest possible image quality relies not only on using the best available equipment, but also making correct photographic choices. Correct use of exposure, lighting techniques, and post processing techniques all effect the overall quality...

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Image Stabilization

What Does Image Stabilization Mean When Talking About Photography? When talking about photography ‘image stabilization’ refers to a technique used within camera hardware to reduce the effects of camera shake. There are two main types of image stabilization, lens based and camera based. Lens based image stabilization uses floating lens elements which move independently of the lens barrel to reduce the effects shake. Camera based image stabilization allows the image sensor to move independently to the camera body to mimimize unwanted sensor movement. Image stabilization is extremely helpful in any situations which require longer exposure times, for example when...

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Infinity

What Does Infinity Mean When Talking About Cameras and Lenses? When talking about photography, and specifically photographic lenses the term ‘infinity'(∞) refers a focus setting where everything beyond the lens’ ‘hyperfocal distance’ will be in focus. Technically speaking, when a lens is set to infinity focus, rays of light reaching the photographic medium do so completely parallel to each other. In reality this is not quite the case due to limitations in optical manufacturing. Focusing to infinity allows a photographer to quickly ensure that an object beyond the hyperfocal distance is in focus without having to physically check focus through...

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Infra-Red

What Is Infra-Red and How Is It Used When Taking Photographs? The term ‘infra-red’ refers to a frequency of light invisible to the human eye. Infra-red gets it’s name from its position in the light spectrum, between the red edge of the visible spectrum at 700 nanometers and 1mm. Infra-red light can be used to control photographic equipment, a beam of infra-red light can for example be used to trigger an off camera flash unit. Infra-red light is also used in AF assist illuminates found on flash units; a grid of infra-red light is projected over a subject which helps...

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