AF28-200mm Super Zoom XR F/3.8-5.6 Aspherical (IF) MACRO (Model A03)
Amazingly compact 28-200mm high power zoom lens!
With a minimum object distance over the entire zoom range of 49cm, and a maximum magnification ratio of 1:4 (at 200mm), this remarkable lens achieves high magnification zoom performance with the compact size of a standard zoom lens. Through XR (Extra Refractive Index) glass and efficient use of aspherical elements, Tamron has achieved a 25% reduction in size and a 27% reduction in weight over the previous model (Model 371D), along with a two-step smaller filter diameter of 62mm without compromising the superior image quality.
Our mission was to create a new standard for zoom lenses in the 21st century. To achieve this, we knew we would need to transcend our conventional engineering expertise to develop entirely new design and manufacturing techniques. Our development of revolutionary new optic design concepts borders on the realm of discovery. The result: optics that enable use of a slimmer body. The precision technology to fit more components into a smaller space. And innovative production engineering to craft superior quality lenses.
Revolutionary New Optics That Achieve Superior Image Quality and Compactness in the Same Zoom Lens
Our basic design objective was to minimize the overall length of the optical configuration. We succeeded in developing optics that allow for a smaller lens diameter while maintaining the same aperture value as previous 28-200mm lenses. Optical power was enhanced with XR (extra refractive-index glass), and we employed three aspherical lenses, each of which do the job of several lens elements combined, to reduce and eliminate aberration in the shortened optical configuration.
The first most important reason that the lens is so compact is the use of high refractive index glass. That is, XR glass. High refractive index glass bends light more than normal or lower refractive index glasses. Normally, glass material having a refractive index of more than 1.69 is called high refractive index glass. In the A03 optical system, glass material having a refractive index of more than 1.69 is used in the front group. In addition, refractive index of the whole optical system is enhanced. By using high refractive index glass in the front group, we could make the elements in the first group thinner, and reduce one element in the second group. This made the overall length of the whole optical system shorter.
The Moving Triple Cam - A New Mechanism Reduced To Fit a More Compact Barrel
Key to the perfection of the new lens was development of a new mechanism to achieve rock-solid stability during the radical barrel movement between the retracted 28mm position to the extended 200mm position: the Moving Triple Cam. This remarkable new mechanism transforms the conventional fixed trip cam into a moving unit that slides in conjunction with the zooming action. In order to fit such a complex mechanism into the compact barrel, the mechanism design was enhanced to incorporate parts and mechanisms of greater precision and performance with less weight and volume. The dramatically compact, lightweight design combined with uncompromising performance and durability were the result.
The lens enables you to get as close to the subject as 0.49m (19.3") for the maximum magnification ratio of 1:4 at 200mm.