- Ultra-wide angle zoom lens.
- Internal silent focusing motor.
- Fast internal focusing.
- One touch focus clutch mechanism.
- Water resistant optical coating on the glass for ease of cleaning.
Based on the high quality optical design of the AT-X 124 PRO DX
(12-24 mm f/4) lens, the AT-X 116 PRO DX has a slightly shorter
zoom range to maintain optical quality at wide apertures and has
an internal silent focusing motor to allow the lens to AF on
Nikon bodies that do not have an AF drive gear and motor.
One Touch Focus Clutch: Tokina's One-touch Focus Clutch mechanism
allows the photographer to switch between AF and MF simply by
snapping the focus ring forward for AF and back toward the camera
to focus manually. There is no need to change the AF-MF switch on
Nikon cameras and there is no second AF/MF switch on the lens for
Canon, everything is accomplished by the focus ring.
Tokina Optical Technology: Aspherical Optics - a standard lens is
made up of a combination of spherical lens elements. Individual
"lenses" within the lens are commonly referred to as "elements".
A spherical element has an even curve to the surface of the
glass. However, there can be problems with such elements; light
entering the centre of the lens and light entering at the edge
may not be perfectly focused at the same point. This is called
spherical aberration. More enhanced computer assisted optical
designs are creating lenses with more spherical elements. More
spherical elements within a lens means a higher risk of spherical
aberration having a negative impact on optical quality.
Wide-angle zoom lenses and wide-angle lenses with large apertures
are especially at risk for spherical aberration.
To eliminate spherical aberration, Tokina employs aspherical
all-glass elements in many of its optical designs to correct this
problem. The aspherical shaped surface of the lens element
focuses light rays entering both the centre and edge of the
element correctly at the film plane for an accurately focused
image. In addition to correcting spherical aberration, these
elements fully correct light quantity and distortion at the edge
of the image and provide excellent results when used in
combination with a floating element design.
Through a close collaboration with Hoya Corporation, one of the
world's largest optical glass manufacturer, Tokina has succeeded
in producing high quality precision moulded glass elements with a
bigger aspherical shape than any other lens manufacturer. This
technique is unparalleled in its technological sophistication and
precision.
F&R Aspherical: This lens, the AT-X116 PRO DX encompasses
Tokina's new F&R aspherical moulded glass elements. These give
outstanding performance with very even illumination in the
corners and correction of spherical aberration across the image
area.
SD Super Low Dispersion: When standard optical glass is used in
telephoto lenses, a phenomenon called chromatic aberration can
occur. Chromatic aberration is the inherent tendency for glass to
disperse (separate) a ray of light into the colours of the
rainbow. The rainbow effect created by a glass prism is the most
dramatic demonstration of chromatic aberration. In lenses, it is
much less pronounced, but still creates slightly out of focus
colours, akin to an "optical noise" that has a negative impact on
the quality of the picture. To eliminate chromatic aberration,
Tokina employs special glass material having super- low
dispersion (SD) properties.
Lenses in the Tokina line-up with the SD mark incorporate these
Super-Low Dispersion glass elements, minimising the secondary
spectrum or optical noise caused by chromatic aberration.
HLD: Tokina's wide-angle and standard zoom lenses feature a
higher quality of optical glass known as Tokina HLD
(High-refraction, Low Dispersion) glass. Having higher refractive
index and lower dispersion properties, HLD glass is far less
likely than standard optical glass to create lateral chromatic
aberration, which is often a problem with conventionally designed
wide-angle lenses.
Multi-Coating: Reflections off the surface of lens elements are
the enemy to any photographer and to every lens manufacturer.
They are reduced or eliminated by bonding multiple layers of a
transparent anti-reflection to the surface of the glass.
Tokina has developed and enhanced a coating technique for its
optics so that they will maintain faithful colour reproduction
and render clean, sharp images.
Mechanical Technology - Floating Element System: When designing a
lens, Tokina calibrated its astigmatism at the points between
minimum focus distance and infinity so that it will give the
better image results at each settings. However, when there are
large differences between the focus limits, effect calibration is
not possible. A floating element system incorporates optical
elements that move in proportion to the focus setting of the
lens. This allows astigmatism to be corrected. Many Tokina lenses
employ floating element systems to provide optimum correction of
astigmatism from minimum focus distance to infinity.
Internal Focus System: The two most used methods of focusing a
lens are either the complete straight forward movement of lens
elements (used mainly with single focal length lenses) or the
rotation of the entire lens barrel group (used mainly with zoom
lenses). The internal focusing system used by Tokina move each
element group within the lens, but does not change the overall
length of the lens. This is especially useful with telephoto
designs.
The internal focusing system has a number of advantages
including: faster focusing, improved handling due to fewer
movements near the centre of gravity, more compact lens designs,
superior use of filters because the barrel with the filter thread
does not rotate.
Focus Clutch Mechanism: Tokina AT-X PRO series lenses feature the
patented "Focus Clutch" Mechanism for sw the lens between
auto focus and manual focus modes.
The manual focusing ring can move (be snapped) back and forth
between an AF and MF position. When the focusing ring is forward
in the AF position, it is not engaged to any of the internal
focus gearing and will turn freely. Without the added weight of
the metal ring the camera can auto focus the lens more quickly
and smoothly.
For manual focus, simply rotate the focus ring the way to one
side or the other on the focus travel, either infinity or it's
closest focusing distance, then pull back (towards the
plate) on the manual focus ring. While pulling back, rotate the
ring from one side of the focus travel to the other. When the
gears align, the focus ring will snap back into the MF position
and the lens can be focused manually.
To return the manual focus ring to auto focus mode, simply snap
the ring forward from any point.