The AF-S DX Zoom-NIKKOR 18-135mm f/3.5-5.6G IF-ED
is a DX format lens that delivers the equivalent perspective to a 27-203mm full 35mm film format lens
Featured NIKON Sophistications: SUPER-ED; AS; IF; SWM and G(Gelded ie no mechanical F-Stop coupling consequently crippling use on earlier camera bodies) (This actually is a profound compatibility limitation.)
Super ED glass elements: Use of Super Extraordinary Dispersion elements very effectively reduce chromatic aberration at high magnifications. Nikon’s Extra-low Dispersion (ED) and Super ED glass help correct chromatic aberrations, caused when different light wavelengths do not converge at the same point after passing through optical glass. Calcium fluorite crystals were once used to correct this problem in telephoto lenses, but the substance thermally fragile, cracked easily and was hyper sensitive to temperature changes. So Nikon invented ED glass, which offers all the benefits, but none of the serious drawbacks of calcium fluorite-based elements. ED glass is now an essential element in NIKKOR’s telephoto lenses, helping deliver very much improved sharpness and contrast, even at maximum aperture.
AS/Aspherical Elements: Aspherical lenses are lenses with complex non-spherical curved surfaces, such as where the radius of curvature changes linearly or non linearly according to distance from the optical axis. Spherical lenses are subject to aberration and therefore cannot properly concentrate all the light into one point. Aspherical lenses, however, offer excellent aberration correction performance, which provides superior resolution, even with compact optics composed of a small number of elements. The technology Nikon employs here is based on its long experience in aspherical fabrication going back to it original AF28-70mm zoom which employed plastic aspherical plastic bonded to a more conventional glass element.
IF: Internal Focusing: With this focusing method the lens is divided into three basic groups with the central group moving with respect to the other two, which remain stationary during focusing, for focusing.
SWM: Silent Wave Motot: The Nikon Silent Wave Motor uses ultrasonic traveling waves to focus AF-S NIKKOR lenses. The ultrasonic waves drive the cylindrical motor that moves the lens elements. This motor system provides instant startup, high-speed autofocusing and accuracy. The Silent Wave Motor represents a significant advance for AF lens technology bringing Nikon to a point that Canon achieved over a decade ago employing patents that were granted originally to Nikon decades earlier. Conventional autofocus lenses are driven by a motor in the camera linked to the lens by a gear system. Using inaudible ultrasonic frequencies rather than a motor/gear system results in much smoother, silent AF operation.
