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Alongside the unique attributes of the APD element, the lens also incorporates three low dispersion elements and one extra refractive index element to control chromatic aberrations and color fringing, as well as produce a great deal of overall clarity and sharpness. The lens is also characterized by its manual focus, manual aperture design, that provides a wealth of control over focus and exposure to benefit working with the APD element.
- Short telephoto prime designed for full-frame Pentax K-mount cameras, this lens can also be used on APS-C models where it provides a 157.5mm equivalent focal length.
- Optical design incorporates an apodization element that helps to improve the quality of bokeh. This element, which resembles a radially graduated ND filter that tapers from clear in the center to more dense around the edges, produces more circular out-of-focus highlights for more pleasing selective focus and shallow depth of field effects.
- To control the effect of the apodization element, two separate diaphragms are incorporated in the lens’ design: a 14-blade diaphragm that works mainly in conjunction with the APD element to control bokeh, as well as a standard 8-blade diaphragm at the rear of the lens design to control the overall light transmission and affect depth of field.
- Due to the incorporation of the APD element, the lens offers an effective light transmission value of T3.2, while the f/2 designation relates mainly toward the potential for selective focus and depth of field control.
- Beyond the APD element, the lens also features three low dispersion elements and one extra refractive index element, which combine to limit chromatic aberrations throughout the aperture range and contribute to a high degree of sharpness and clarity.
- A manual focus design permits fine-tuned control for focusing as closely as 3′ away with a maximum magnification of 0.16x.
- Two manual aperture rings enable you to adjust both the exposure-affecting diaphragm as well as the APD-affecting aperture.
