Parfocal

What Does Parfocal Mean When Talking About Camera Lenses? When talking about photography and photographic lenses a ‘parfocal’ lens is a zoom lens that maintains focus when the focal length of the lens is altered. The opposite of a parfocal lens is a ‘varifocal’ lens. Parfocal lenses are extremely convenient because they allow a photographer to quickly alter their perspective of a scene without having to refocus. The advent of autofocus lenses and digital cameras has somewhat overcome the problems caused by using varifocal lenses as camera software is able to quickly and automatically refocus an image when lens focal …

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Perspective Control Lens

What Is A Perspective Control Lens? Perspective Control is the name that Nikon gives to its tilt-shift lenses. For more detailed information on how they work and why you might want to use one, please view the tilt-shift lens glossary entry.

Pin-Cushioning

What Is Pin-Cushioning and How Does It Effect Photography and Photographs? When talking about photography and taking photographs the term ‘pin-cushioning’ refers to a kind of distortion which makes images appear ‘pinched’ in the middle. The term gets its name from the effect pushing a pin into a pin-cushion has on its appearance. Pin-cushioning is a problem associated mainly with cheap telephoto zoom lenses such as those found on point and shoot cameras. The effects of pin-cushioning can be corrected in post-processing or by using higher quality equipment. The opposite of pin-cushioning is ‘barrel distortion’ which causes an image to …

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Screw-On Filter

What Is A Screw-On Filter? Most camera lenses have a thread on the front that allows us to add filters to modify the light coming into the lens in some way. Sometimes we use polarizing filters to cut down on reflections in our image, and sometimes we just want to use a neutral density filter that allows less light into the lens and gives us a slower shutter speed for special effects. Screw-on filters can be added to this thread on the front of the lens, and they come in many sizes to fit the varying diameters of lenses. In …

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Shift Lens

What Is A Shift Lens? A shift lens is similar to a tilt-shift lens, except that it lacks the tilt mechanism. For a detailed look at both shift and tilt mechanisms, please view the tilt-shift lens glossary entry.

STF

What Does STF Mean When Talking About Photographic Lenses? An STF, or Smooth Trans Focus lens is Sony’s name for a lens that uses an apodization element. In simple terms an apodization (also referred to as an APO or APD 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 edges of out of focus objects within an image, creating beautifully soft Bokeh and an …

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Teleconverter

What Is A Teleconverter? A teleconverter is an optical accessory lens that is mounted between the camera body and a regular lens. It has the effect of increasing the focal length of the lens, but also simultaneously decreases the maximum aperture of the lens. The most common focal length multipliers for teleconverters (sometimes called extenders), are 1.4x and 2x, although Nikon also makes a 1.7x version as well. Not all lenses are physically capable of accepting a teleconverter, due to the protruding optical element that actually reaches inside the regular lens. Most long lenses can accept them, most wide angle …

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Tilt-Shift Lens

What Exactly Is a Tilt-shift Lens? A tilt-shift lens allows a photographer to alter the angle between the focal plane and the camera sensor. This adjustment allows compensation for the Keystone effect, which causes parallel lines in an image to converge if the camera is not perfectly level. Tilt-shift lenses can also be used to increase depth of field at wide apertures, and are extremely popular with landscape and architectural photographers. The nature of the design of tilt-shift lenses makes the implementation of autofocus mechanisms far too complicated to be practical therefore all current tilt-shift lenses are manual focus only …

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Tripod Collar

What Is A Tripod Collar? A tripod collar, sometimes also called a lens collar, is a lens accessory that allows the lens to be mounted to a tripod. When the weight of a lens reaches a certain threshold, it’s no longer safe to mount the camera to a tripod as the weight of that lens would put too much strain on the lens mount. Instead, a tripod collar is used on the lens and this provides an easy way to support your setup under the lens instead of the camera. Large telephoto lenses of 300mm and upwards usually have permanently …

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Tripod Mount Ring

What Is A Tripod Mount Ring? A tripod mount ring is just another name for a tripod collar. Please see the tripod collar page for a more detailed description of what it is, what it does and why you might want to use one. Additional Reading