Tokina AT-X 12-28mm f/4 Pro DX Lens for Canon

Wide Zoom Range 

The new Tokina AT-X 12-28mm f/4 lens has a super-wide to standard zoom range while maintaining a constant fast f/4 apertureAPERTUREAperture, shutter speed and ISO form what is known as the exposure triangle in photography. Aperture refers to an opening inside the lens, similar to the iris of your eye, that changes in diameter to control the amount of light that enters a camera. Aperture is expressed in f-stops: the lower the number, the larger the aperture, e.g. f/1.4 is larger than f/8. A larger (or wider) aperture allows more light to pass through the lens to the sensor (film) as a picture is taken, particularly useful in low-light conditions. A larger aperture also produces a shallower depth-of-field, and thus more background blur.. This makes it a very versatile lens for different photo applications such as scenery, street photography and event coverage. The lens is designed for DSLR cameras with APS-C (DX) sized sensors. 

New Optical Design 

A new optical design using aspherical elements and super-low dispersion glass matches even the highest megapixelPIXELThe shortening of 'picture element', a basic unit of programmable colour forming the dots that make up an image. Pixel size depends on a camera’s resolution, which is measured in megapixels (MP), meaning millions of pixels. The more pixels on a sensor, the smaller they have to be to fit. An image's number (or density) of pixels correlate to the amount of information and image holds. Cameras with more pixels on the sensor have a higher pixel density and thus more resolving power, able to capture smaller details with much more clarity and accuracy. Higher resolution images can be cropped more agressively and also produce better quality large prints. DX sensor cameras available today. 
One aspherical lens element is positioned in the front group. This together with another precision molded glass aspherical lens element placed in the rear group ideally focuses marginal light rays and maintains sharpness at the edges while also correcting distortion. The use of two different SD (Super-low Dispersion) glass elements, type FK01 and FK03, corrects chromatic aberration. The combination of all these specialized elements in the optical design yield excellent sharpness and colour. 

New auto focus mechanism 

The new AF “GMR magnetic precision” control sensor is capable of fast auto-focus. Tokina placed the new sensor closer to the drive unit in the lens for faster communication between the controller and AF motor. This combined with the motor's high-precision focus control yields faster, more accurate auto-focus. 

Additionally, a brand new “SD-M” (Silent Drive-Module) has greatly lowered the sounds emitted by the auto focus drive system allowing for much quieter AF. Both Canon and Nikon mounts have a built-in AF motor to make them auto-focus compatible with all current camera bodies.

 

Compact body design 

The Tokina AT-X 12-28mm f/4 compact design makes the lens easy to carry and handle. Manual focus is achieved through Tokina's one-touch focus clutch AF/MF mechanism. Simply slide the manual focus ring forward for auto-focus or back for manual focus operation. The lens focus ring is damped in the manual mode for smooth and precise focusing.