A New Pentax Wide-Angle Lens for Large Sensors

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The recently announced Pentax SMC DA 645 25mm f/4 AL (IF) SDM AW lens is a highly attractive optic that fills the previous void for a wide-angle lens that can be used with the Pentax 645D camera system. This lens’s ultra wide focal length, equivalent to 19.5mm in 35mm format, features a 95-degree angle of view for wide, sweeping views and a tremendous hyper-focal distance. The DA 645 25mm f/4 incorporates the Pentax SDM autofocus system for quick and quiet operation and it also utilizes a Quick Shift focus system for disengaging the AF motor entirely, allowing instant switching between auto and manual focusing.

In terms of optical quality, the lens is composed of 12 glass elements within 8 groups. The glass features an Aero Bright coating for reducing chromatic aberrations and other distortions that are inherent to wider-angle lenses, as well as providing greater light transmission to your camera’s imaging sensor. The lens’s rounded diaphragm blades produce an attractive out-of-focus quality that is especially prevalent when photographing at wider apertures.

The design of the lens features both Pentax’s SP coating and rigorous weather- and dust-sealed construction for maximum protection from the elements and greater ease during cleaning. Due to the wide-angle design, the front lens element is also convex and does not accept standard screw-in filters; there is an inline filter system in the center of the lens which accepts 40.5mm drop-in style filters.

The DA 645 25mm f/4 is only compatible with the Pentax 645D camera system and will not cover 6 x 4.5 film sizes.  The lens also includes a clear and circular polarizer filter for use with the inline filter design.

Focal Length 25mm (19.5mm equivalent in 35mm format)
Aperture Range f/4-32
Elements/Groups 12/8
Angle of View 95° 
Max. Magnification 0.11x
Focus System SDM autofocus with Quick Shift for switching between auto and manual focus
Minimum Focus Distance 1.31' / 0.4m
Number of Aperture Blades 9 (rounded design)
Diaphragm Control Fully Automatic
Lens Mount Pentax 645 AF2 Bayonet
Filter Diameter 40.5mm (inline/drop-in, not front mount)
Dimensions 3.5 x 5.8" / 90 x 148.5mm
Weight 36.7 oz / 1040 g