Adjustment Layer

What Is an Adjustment Layer and How Is It Used in Image Editing? 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. Adjustment layers allow photographers to experiment with edits to their photographs without risking permanently changing the original image content. Adjustment layers can also be copied and applied to …

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What does it mean when a camera or lens has the letters AF on the side of it? Click through to find out in our photography dictionary.

AF Assist Lamp

What Is an AF Assist Lamp and What Is It Used for in Photography? An AF assist lamp is a small light, usually built into a camera body above the lens mount. It is used to assist the camera in focusing on a subject in low light conditions by lighting up the subject area while the camera focuses. AF Assist lamps only work at very short distances due to the low power of their output and in order to work correctly they must only be lit whilst the camera focuses. Were an AF assist lamp to remain on whilst a …

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What Does AL Mean In Photography? AL is an abbreviation of Aspherical Lens and is often used by the manufacturer, Pentax.  Please see the aspherical lens definition page for more details.   Additional Reading What Is An Aspherical Lens? What Does DO Mean On A Canon Lens? Pentax Lens Terminology And Abbreviations  


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 can …

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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 …

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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 system. …

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Apodization Filter

An apodization filter is a graduated neutral density filter that sits inside the back of a lens, and helps to smooth out the transitions in out-of-focus highlights or “bokeh balls”. Whilst the effect is most obviously seen in these highlight areas, as you can see from the Sony example below, the filter also causes a general smoothing of all OOF background areas. In short, if you want awesome, creamy looking bokeh, a lens with an APD filter is the way to go. So why haven’t we seen more of these lenses then, if they produce such a generally desirable result? …

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ASP Lens Definition ASP is an abbreviation for Aspherical Lens and is used by the manufacturer Sigma, to denote lenses which contain an aspherical lens element.  Please see the aspherical lens definition page for more details on this optical type.   Additional Reading What Is An Aspherical Lens?   Sigma 14mm f/2.8 ASP


ASPH Lens Definition ASPH is an abbreviation of Aspherical Lens and is used by the manufacturer, Leica to denote lenses that contain an aspherical lens element.  Please see the aspherical lens definition page for more details on this optical type.