Glossary

AL

(Aspherical Lenses) contrary to spherical, aspherical lenses do not have a uniformly curved spherical shape. The form of an aspherical lens is adapted to a specific task and the curvature of each is individually computed. The production of these lenses is accordingly complex. The greatest advantage of aspherical lenses: several types of optical aberrations can be corrected at one time. They are used particularly in highquality lenses allowing for the use of fewer lens elements so that a high luminous intensity is attained.

ED Glass

Normal glass lenses tend to divide the incident light into its various colour components, as a prism would do. This happens particularly at the edges, adding unwanted colour fringing to the photo. The longer the focal length of the lens the more apparent is the fringing effect. ED glass is an exceptionally highquality special glass that prevents this socalled chromatic aberration to a very great extent.

IF

(Inner Focusing) Each lens is composed of several groups of lens elements. With an Inner Focusing design only one of these groups is moved. Inner Focusing brings a number of advantages compared to a conventional focusing design where all the lens groups are moved: it works faster and the overall length of the lens remains unchanged so the centre of balance remains constant. additionally, since the front lens element doesn’t rotate, filters do not have to be readjusted every time the focus point changes.

Limited Edition

“Limited Edition” is the PENTAX lens series that is characterised by extremely high quality standards. Since more expensive materials are used and a complex production process employed, PENTAX manufactures a restricted number of the “Limited Edition” lenses on a daily basis.

SDM

(Supersonic Direct-drive Motor) Small motors manage the actual focusing of an autofocus system. With the “Supersonic Direct-drive Motor” PENTAX has developed a technology that propels the focusing procedure with an ultrasonic motor. PENTAX SDM lenses drive the autofocus system significantly faster and operate more quietly than conventionally driven AF lenses.

smc

(super multi coating) super multi coating is the benchmark of all PENTaX lenses. smc describes a high quality coating of the lens elements that consists of seven microscopically thin layers. The normal light loss at the lens surface between air and glass is reduced from 4 % to 0. %.

smc-DA

The designation is for lenses designed specifically for PENTAX digital SLR cameras. They are not compatible with 35mm film SLRs.

smc-DA*