Glossary of Nikon Lens Technology

Glossary of Nikon Lens Technology

Aspherical Lens - ASP

Thanks to Aspherical Lens Elements, lenses incorporating special optical characteristics can be made. The use of aspherical lenses means lens can be made smaller, lighter and, in general, better than similar lenses which employ only spherical elements. Nikon introduced the first photographic lens with aspherical lens elements in 1968: the 10mm F5.6 OP fisheye. The world’s fastest 28mm lens, the AF Nikkor 28mm f/1.4D, uses an aspherical element to ensure its compact size and to obtain superb performance by eliminating sagittal, or arrow-shaped coma, even at its widest aperture. An aspherical lens element has a surface curved to the ideal shape to correct these aberrations. Aspherical lenses virtually eliminate the problem of coma and other types of lens aberration – even when used at the widest aperture. They are particularly useful in correcting the distortion in wide-angle lenses.Nikon employs three types of aspherical lens elements:

    • Precision-ground Aspherical lens elements are the finest expression of lens crafting art, demanding extremely rigorous production standards.
    • Hybrid lenses are made of a special plastic moulded on to optical glass.
    • Moulded glass aspherical lenses are manufactured by moulding a unique type of optical glass using a special metal die technique.

    For more information on Aspherical lenses click here.

    AF DC-Nikkor lens
    One of Nikon’s unique contributions to portrait photography is Nikon's exclusive defocus-image control DC (Defocus-image Control) technology.

    DC control OFF

    DC control ON

    Notice the foreground is still in focus but there is a subtle change to the background focus.

     

    This Nikon innovation enables users of AF DC-Nikkor lenses to control background and foreground blur precisely by allowing photographers to control the degree of spherical aberration in the foreground or background by rotating the lens DC ring, resulting in striking portraits. This will create a rounded out of focus blur that is ideal for portrait photography. These lenses are unique to Nikon.

    AF-S Nikkor lens
    Nikon’s AF-S technology involves the integration of the Silent Wave Motor or SWM into supertelephoto lenses such as the 300mm, 400mm, 500mm and 600mm, and zoom lenses with fast maximum aperture like 17-35mm, 28-70mm and 80-200mm. This gives these lenses quick, ultra-quiet autofocus operation, making them ideal for sports and fast-action photography. Nikon is now incorparting this technology across the Nikon lens range in lenses such as the 24-85 AFS -G lens.
    The SWM technology used in Nikons AF-S lenses, work by converting travelling waves into rotational energy to focus the optics. The ultrasonic travelling waves move in a spiral pattern inside the lens barrel. The motor is positioned on top of the waves, and they drive it from below. In principle it is similar to surfing, the waves drive or push the surfer provided he's balanced atop them. This enables high speed auto focusing that’s extremely accurate and super quiet. The lens receives the power for it's internal focusing motor and the focusing instructions from the camera body and therefore can only be used with suitable cameras.

    AF-S Motor

    Close-Range Correction (CRC)
    Close focusing is a very desirable characteristic for any lens. A telephoto lens that focuses closer can produce dramatic results. Even a wideangle lens that can focus close creates opportunities for interesting perspectives.

    AF 24mm F2.8D

    Nikon is a pioneer in the development of Close-Range Correction (CRC) systems. Sometimes referred to as “Floating Element” designs, wherein each lens group moves independently to achieve focusing. This ensures superior lens performance even when shooting at close distances. The CRC system is used in Fisheye, wide-angle, micro and selected medium telephoto Nikkor lenses to provide comparable performance at both near and far focusing distances. CRC is yet another example of how Nikon designers constantly strive to provide Nikon’s Nikkor system lenses with advanced and high-performance capability.

    D - Distance Information
    D-type and G-type Nikkors relay subject to camera distance information to AF Nikon cameras bodies via an encoder in the lens. This makes possible advances like 3D matrix metering and 3D Multi-sensor balanced fill flash.

    DX
    Nikon introduced a new series of lenses designated DX Nikkor. These DX Nikkor lenses are designed for the 24 x 16 mm (approx) sensor format used in Nikon ‘D series’ SLR camera range: D1, D1X, D1H D100, D70 and D2H, and are designed to address the market's need for wider angle-of-view high-performance optics for digital SLR photography. For more information on DX lenses click here.

    Extra-low Dispersion - ED glass
    Developed by Nikon optical designers and Nikon glass specialists, ED (Extra-low Dispersion) glass used in selected telephoto and telephoto zoom lenses provides superior sharpness and colour correction by effectively minimizing chromatic aberration to a degree that is remarkable in telephoto lenses. Put simply, chromatic aberration is a type of image and colour dispersion that occurs when light rays of varying wavelengths pass though optical glass. This is best descibed as the three colours that make white light (red, blue and green) when passed though a lens are seperated, the results of this is that the three rays may not meet again in the correct place to produce a sharp image.

    ED glass prevents this dispersion/seperation of light, thus producing sharper images. In the past, correcting this problem required special optical elements that offer anomalous dispersion characteristics- specifically calcium fluoride crystals. However fluorite cracks easily and is sensitive to temperature changes that can adversely affect focusing by altering the lens refractive index.

    Nikon designers and engineers put their heads together and came up with ED glass, which offers all the benefits, yet none of the drawbacks of calcium fluorite based glass. With this innovation, Nikon developed several types of ED glass suitable for various lenses.

    They deliver stunning sharpness and contrast even at their largest apertures. In this way, Nikkor ED series lenses exemplify Nikon’s pre-eminence in lens innovation and performance.

    G - Genesis
    Nikon introduced a new series of lenses called AF-G. For more information on G lenses click here.

    IF Internal Focusing
    Imagine being able to focus a lens without it changing in size, Nikon’s IF technology enables just that. Previously to 1977 when Nikon introduced IF lenses, telephoto lenses required large amounts of turning the focus ring to move the front lens elements back and forth to allow focusing, making the lens longer as you focused. With some large telelphoto lenses, special screwing handles could be added to make focusing easier.Using IF designs, all internal optical movement is limited to the interior of the non extending lens barrel.

    This allows for a more compact lightweight construction as well as a closer focusing distance. In addition, a smaller and lighter focusing lens group is employed to ensure faster focusing. The IF system is featured in most Nikkor telephoto and selected Nikkor zoom lenses. Among these are the AF-S Nikkors which have virtually become standard equipment for fast-breaking sports photography around the world.

    Nano-Crystal Coat Technology
    Nikon has developed a Nano-Crystal Coat, a new anti-reflective lens coating technology that reduces ghosting and flare, particularly on images shot in bright sunlight or under intense lighting.

    Image taken using lenses without Nano-Crystal coatImage taken using lenses with Nano-Crystal coat

    This technology was developed as a by-product of Nikon’s NSR (Nikon Step and Repeat) semiconductor manufacturing systems.

    Nano-Crystal Coat seen through a microscope

    Phase Fresnel (PF)
    Using the advanced optical technologies at its disposal, Nikon has been able to create Phase Fresnel (PF) lenses allowing the manufacture of smaller, lighter and more cost-efficient teleconverter lenses. The first teleconverter lens to uses this technology is the TC-E3PF for the COOLPIX 8400, which offers an 18% reduction in length and a 33% reduction in weight compared to the TC-E3ED.

    A cut-away illustration of the TC-E3PF showing the PF lens highlighted in yellow.

    One of the advanced properties of PF lenses is the ability to correct chromatic aberration, in a similar manner to ED lenses.With its manufacturing expertise and aspherical lens production capability, Nikon is in an ideal position to implement this technology successfully in other types of lenses too.

    Rear Focusing
    In Nikon’s rear focusing (RF) system, all the lens elements are divided into specific lens groups, with only the rear lens group moving for focusing.

    AF-DC 135mm F2D

    Since rear lens groups are smaller than front lens groups, especially in high-speed telephoto lenses, RF technology makes it possible to drive the lens smoother and faster. RF also contributes to high optical performance.

    Super ED glass
    Super ED glass is a new development of Nikon’s own ED glass technology. Nikon optical designers and Nikon glass specialists developed Super ED glass to have optical properties resembling that of fluorite. Super ED glass exhibits an even lower refractive index and lower light dispersion than ED glass, while also excelling at eliminating secondary spectrum and correcting chromatic aberration.

    AF-S VR 200mm F2G IF ED lens

    Super ED glass is not as susceptible to cracking as the crystalline structure of fluorite and demonstrates less change in optical performance when exposed to rapid changes in temperature (known as thermal shock) than fluorite. Lenses that use Super ED glass deliver outstanding optical performance even under harsh shooting conditions, producing unparallel sharpness and contrast though out the aperture range including usage at faster apertures. Super ED glass is a demonstration of Nikon’s commitment to optical innovation and excellences.

    Super Integrated Coating- SIC
    To enhance the performance of its optical lens elements, Nikon employs an exclusive new multilayer lens coating that helps reduce ghost and flare to a negligible level. An improvement on Nikon’s breakthrough “NIC” coating, Nikon Super Integrated Coating achieves a number of objectives, including minimized reflection in the wider wavelength range and superior color balance and reproduction. Nikon Super Integrated Coating is especially effective for lenses with a large number of elements, like Zoom-Nikkors.

    The top half of this element has not been coated with SIC, while the bottom section has been coated with SIC.

    Also, Nikon’s multilayer coating process is tailored to the design of each particular lens. The number of coatings applied to each lens element is carefully calculated to match the lens. The type and glass used to assure uniform colour balance are what characterises Nikkor lenses. This results in lenses that meet much higher standards than the rest of the industry.

    VR - Vibration Reduction
    This innovative system minimises image blur caused by camera shake, and offers the equivalent of shooting at a shutter speed three stops faster. It allows handheld shooting at dusk, at night and even in poorly lit interiors. The VR system also detects automatically when the photographer pans - no special mode is required.

    The VR lens group is fitted with two angular velocity sensors. One detects "pitching" (up-down rotation on a particular axis), and the other detects "yawing"(left-right rotation, again on a particular axis).
    Calculations are immediately performed based on collected data, and the results are used to compute the target position to which the VR lens group is to be moved. Voice-coil motors (VCM) then move the VR lens group into that position. This is not a simple drive, but rather a continuously-monitored motion, meaning that the processor constantly checks to see whether or not the lens is at the correct position. Believe it or not, all of these operations are handled by the microcomputer in the incredibly short interval of 1msec - a mere 1/1,000th of a second.
    Fortunately, the VR Nikkor lens is very advanced. It is actually capable of judging whether or not motion is intentional such as panning, and of correcting only movement it determines to be unintentional. The secret to this is in the algorithms built into the VR Nikkor lens. These algorithms were developed from about 5,000 camera shake data samples, taken in order to determine what types of camera shake occur under what conditions. The VR mechanism is designed to allow the photographer to move the lens freely, while correcting those accidental hand motions made by all photographers, experienced or not.

    VR lens unit

    The VR Nikkor lens benefits photographers in numerous ways. Slower shutter speeds can be selected in three steps, making the lens ideal for taking telephoto shots in a situation such as a football game played at night. It also makes it easier to use low-sensitivity colour reversal film. With the relaxation in shutter speed restrictions, you don't have to carry a tripod all the time.
    For more information on VR lenses and their operation click here.

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