|Tamron AF18-250mm lens|
Ralf Jurrien : December 17th 2007 - 01:02 CET
Tamron AF18-250mm lens : Mr. Morio Ono, of Tamron Co., Ltd., announced that the company has released the Tamron AF18-250mm F/3.5-6.3 Di-II LD Aspherical (IF) Macro, a lightweight, compact and ultra high power zoom lens designed exclusively for digital SLR cameras with APS-C sized image sensors with a Built-In Motor for Nikon. The AF18-250mm F/3.5-6.3 Di-II LD Aspherical (IF) Macro is the ultimate high power zoom lens boasting the world’s greatest zoom ratio of 13.9X, a milestone that Tamron, the pioneer of high power zoom lenses, has achieved by commanding its technologies to further expand the capabilities of high power zoom lenses. The Tamron AF18-250mm lens will be available from December 2007 in Japan.|
Tamron AF18-250mm F/3.5-6.3 Di-II LD|
Tamron’s concept for the development of high power zoom lenses is “one-does-it-all, covering wideangle to telephoto” to satisfy customer needs for simplicity. Tamron has always kept this concept in mind when designing higher power zoom ranges. The question, “to what extent can the tele-end of a zoom starting with 18mm wideangle be extended in a lens designed for exclusive use with digital SLRs?” was posed and answered with the development of this ultra high power zoom lens possessing the world’s largest zoom ratio of 13.9X. It is not too long ago that the world of “wideangle to ultra telephoto film photography” could only be achieved with a combination of two zoom lenses; 28-200mm + 200-400mm. Now, the world of digital SLR photography can be enjoyed with just a single zoom lens!
Advanced optical design
The optical system uses an LD (Low Dispersion) glass element and one AD (Anomalous Dispersion) lens in the first group to minimize on-axis chromatic aberration while achieving the 250mm ultra-tele focal length. In addition, suitable positioning of two hybrid aspherical lens elements serves to meet the desired compactness despite its 13.9X zoom power. In particular, Tamron’s engineers have pursued a thorough analysis of the optical configuration of the third lens group for optimum power distribution in the overall optical system. The approach has resulted in the sufficient compensation of aberrations, including astigmatism; the compactness, thanks to downsizing of the first group; the high zoom power; and optimum optical quality.
Minimum focusing distance
The new zoom lens achieves a minimum focus distance of 0.45m (17.7”) throughout the entire zoom range, top of the class capability among high power zoom lenses for digital SLR cameras, which results in a maximum magnification ratio of 1:3.5 at the 250mm tele-end.
The zoom lens uses an optical system designed to confine the changing angles of incidence of light rays reaching the imager within a certain scope over the entire image field by considering the effects of variance due to zooming.
High image quality resolution
Since the lens is designed exclusively for digital SLR photography, it provides high image quality resolution, contrast and flatness of image field.
Reduce Ghosting & Flare
Through the use of "Internal Surface Coatings" (i.e., multiple-layer coatings on cemented surfaces of plural elements) and new multiple-layer coating technology on ordinary elements, ghosting and flare due to reflections that occur when light enters through the front element and reflections caused by the imager itself are reduced to the absolute minimum.
Ultra high zoom power
Complicated mechanisms are built into the compact body, thanks to new mechanical devices, for excellent portability and ease of use. Based on the mechanical construction of the AF28-300mm (Model A061), Tamron has revolutionized accumulated mechanical design technologies by reviewing the roles respective barrel parts play in order to achieve the high power, compactness and light weight. Additionally, the production engineering has been completely overhauled to downsize its parts and to increase their precision and durability in order to accommodate the complex structure in the new zoom lens.
Zoom lock mechanism
The zoom lock prevents unwanted barrel extension when carrying the lens/camera combination.
Flower shaped lens hood
A flower-shaped lens hood is included as a standard accessory. The special hood provides optimum shading of superfluous light rays that enter from the rectangular frame outside the image field.
Tamron AF18-250mm lens Specifications
• Model Name : A18N II
• Focal Length : 18-250mm
• Maximum Aperture : F/3.5-6.3
• Angle of View : 75°33’ - 6°23’ (APS-C size equivalent)
• Lens Construction : 16 elements / 13 groups
• MFD : 0.45m (17.7”) (entire zoom range)
• Max. Magnification Ratio : 1:3.5 (at f=250mm, MFD 0.45m)
• Filter Diameter : 62mm
• Overall Length : 84.3mm (3.3”)
• Maximum Diameter : 74.4mm (2.9”)
• Weight : 452g (15.9 oz)
• Diaphragm Blades : 7
• Minimum Aperture : F/22
• Standard Accessory : Flower-shaped Lens Hood
• Compatible Mount : Nikon