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K-mount Lenses

Discontinued : Standard Lenses Wide-Angle Lenses Standard Lenses Telephoto Lenses Macro Lenses

HD PENTAX-DA 18-50mmF4-5.6 DC WR RE

  • Zoom
  • DA

An interchangeable zoom lens, featuring a new retractable mechanism creating the world’s shortest length

This standard zoom lens has been developed as a compact, easy-to-use everyday lens that meets user demand for a downsized, high-resolution digital SLR imaging system. Thanks to its retractable mechanism — employed for the first time in the PENTAX K-mount lens system — it provides the world’s shortest length in the stored position: just 41 millimeters. * Despite its ultra-compact design that assures outstanding portability, it also features the PENTAX-original HD Coating, Anomalous Dispersion Glass elements and aspherical elements to effectively compensate various aberrations for sharp, high-contrast, well-balanced images.

Note: In the case of use with the models below, when the lens is retracted, the display indicating lens retraction is not shown and photographs can be taken. For the K-3 and K-S1, a firmware upgrade is necessary.
K-500/K-50/K-5II/K-5IIs/K-30/K-01/K-5/K-r/K-7/k-x/K-m/K20D/K200D/K10D FW Ver.1.30/K100D Super
Note: With K-7、K-x、K-r、K-5Ⅱ、K-5、K-5IIs, MF will not work during Movie mode. When you use Movie mode, turn on the camera with Still mode and switch to Movie mode.

Digital SLRs only DC Power focus Weather-resistant Quick-Shift Focus SP Coating HD Coating Round Iris Diaphragm Aspherical Lens (AL)


Dedicated Hoods / Dedicated Cap Included
JAN-Code / 4549212 286957

Sample Images

  • Aperture F8.0, Shutter speed 0.3sec, Focal length 35mm

  • Aperture F11, Shutter speed 1.3sec, Focal length 45mm

  • Aperture F8.0, Shutter speed 1/4sec, Focal length 26mm

  • Aperture F8.0, Shutter speed 1/5sec, Focal length 35mm

Main Features

The world’s shortest standard zoom lens
This standard zoom lens offers a zoom ratio of approximately 2.8 times to cover the wide-angle to standard ranges (for focal lengths equivalent to 27.5mm to 76.5mm in the 35mm format), which are the most frequently used ranges in general photographic applications. Thanks to its new retractable mechanism, it measures a mere 41millimeters in length in the stored position — the world’s shortest for a standard zoom lens — to assure outstanding portability in combination with today’s downsized digital SLR camera body.
Dependable weather-resistant construction
This lens features a dependable weather-resistant construction with nine special seals to effectively prevent the intrusion of water into the interior. By pairing it with a weather-resistant PENTAX digital SLR camera body, the user is assured of a durable, reliable digital imaging system that performs superbly in demanding shooting settings — even in the rain or mist, or at locations prone to water splashes or spray.
Exceptional image rendition to accommodate latest digital SLR cameras
Incorporating Anomalous Dispersion Glass elements and aspherical elements in its 11-element/eight-group optics, this lens effectively compensates various aberrations for high-contrast, high-resolution, fine-detailed images with minimal color bleeding.
HD* Coating to improve image description
This lens is treated with the high-grade, multi-layer HD Coating.* Compared with conventional multi-layer coatings, this PENTAX-original coating assures less reflection and higher light transmittance to deliver bright, high-contrast images free of flare and ghost images, even under demanding lighting conditions such as backlight.

* HD stands for High Definition

Quick-Shift Focus System
This lens is equipped with the PENTAX-developed Quick-Shift Focus System, which allows the user to instantly switch to manual-focus operation, even when the camera’s AF system is in operation.
Other features
・SP (Super Protect) Coating applied to the front surface of the lens to effectively repel water and grease
・Smooth, quiet autofocus operation, driven by the built-in DC motor
・Rounded diaphragm to produce a smooth, beautiful bokeh (defocused) effect, while minimizing the streaking effect of point light sources
・Low-profile lens hood (included),designed for easy carrying without the need to remove it from the lens for storage
【MTF Chart】
Geometric optics MTF (MTF calculated without referencing the effects of light diffraction phenomenon)



Wave optical MTF (MTF calculated referencing the effects of light diffraction phenomenon)



Spatial Frequencies S:Sagittal M:Meridional
10 lines/mm
30 lines/mm

Since it is impossible to avoid light diffraction phenomenon on the actual lens, wave optical MTF is more realistic.
However, geometric MTF is appropriate if you want to compare only the effects of geometric aberration correction on MTF.

What is the MTF chart?

Type Standard Zoom
Focal length (Equivalent to 35mm format) 18-50mm(27.5-76.5mm)
Maximum Aperture F4-5.6
Minimum Aperture F22-32
Angle of View 76-31.5°
Lens Construction 11 elements in 8 groups
No. of diaphragm blades 7
Rounded aperture (18mm: F4-5.6   50mm: F5.6-8)
Closest focusing distance 0.3m
Maximum reproduction ratio 0.23x
Filter size 58mm
Diameter x length Approx.71mm x 41mm (2.8 in. x1.6 in.)
Weight Approx.158g /5.6 oz. (with hood Approx.165g /5.8 oz.)

Compatible converters (Click here for details)


Phase-matching:△  Contrast-detection:△

*When mounted, this converter closes down the lens’s maximum aperture by one stop.

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