Special glass for high optical performance
This zoom lens uses a high-precision, large-aperture glass-moulded aspherical lens element and three hybrid aspherical elements to minimise spherical aberration, coma, and distortion. In addition, a pair of LD (Low Dispersion) glass elements and an HID (High Index high Dispersion) glass element together compensate for on-axis and lateral chromatic aberrations, delivering high optical quality.
Sharpens edges by reducing ‘colour fringing’
Chromatic aberration occurs when a lens element refracts different wavelengths of a ray of light – its rainbow colours – at very slightly different angles. This results in the ‘colour fringing’ that reduces the sharpness of an image. LD elements are made from special glass materials with extremely low dispersion indices (i.e. the refraction of a ray of light into rainbow colours is extremely narrow). Thus they effectively compensate for chromatic aberration at the centre of the field (on axis), a particular problem at long focal lengths (the telephoto end of the zoom range), and for lateral chromatic aberration (toward the edges of the field) that often occurs at short (wideangle) focal lengths.
Although costly, LD glass materials result in clear, vivid image quality.
Far superior image quality – while reducing lens size and weight
Tamron uses several hybrid aspherical lens elements in its lenses bearing the Aspherical designation. The benefits are two-fold: first, their non-spherical shapes virtually eliminate spherical aberration and image distortion. Second, as one hybrid aspherical lens element can take the place of multiple elements without compromising performance, they allow the lens to be much more compact.
As a result, these innovative optics have played a crucial role in delivering uniformly high image quality across all apertures and focal lengths of extraordinarily compact ultra-zoom lenses.
High Index High Dispersion
Minimises chromatic aberrations
The use of HID glass elements in a lens minimises on-axis and lateral chromatic aberrations that are the greatest hindrances to achieving high image quality. HID glass has allowed Tamron to produce complex lenses such as long-range zooms that are conveniently compact and lightweight while delivering outstanding performance.
Optimal angles of incidence of light at the imaging sensor
The new ultra wide-angle zoom lens uses a new optical system designed to confine the changing angles of incidences of light rays reaching the imaging sensor within a certain scope over the entire image field, from the centre to the periphery, addressing the effects of variances caused by zooming.
Enhanced peripheral illumination
Peripheral light fall-off that becomes an image-degrading factor in wide-angle photography is minimised to ensure high optical quality from the centre to the periphery.
As an SP Di II class lens, it provides high optical quality in resolution, contrast, and flatness of image field.
Internal surface coatings reduce ghosting and flare
The lens uses newly developed multiple-layer coatings and internal surface coatings (i.e., multiple-layer coatings on cemented surfaces of plural lenses) to reduce the image degradation caused by the reflection of light rays entering from the lens front and affected by the imager.