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Pentax K-m, KA-mount Sigma Mini-Wide II 28mm 1:2.8

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Pentax K-m, Sigma Mini-Wide II 28mm 1:2.8

40mm Equivalents: A look at vintage primes and legacy lenses equivalent to the standard normal primes on 4/3 mirrorless or APS-C digital SLR cameras.

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I am vintage digital photography enthusiast, and a sucker for Sigma Super- and Mini-Wide legacy lenses. After starting off with a couple of Mini-Wides that were unusable due to their coating failure, I went through a couple with FD Mounts: a Sigma 24mm 1:2.8 FD-Mount Super-Wide and a Sigma 28mm 1:2.8 nFD Mount Mini-Wide II, a K-mount Sigma 28mm 1:2.8 Mini-Wide, and an OM-mount Sigma 28mm 1:28 Mini-Wide II, before ending up with what is hopefully the last: a K_A-mount Sigma 28mm 1:28 Mini-Wide II.

The lens series, which began with the 24mm Super-Wide and the more compact 28mm Mini-Wide in the late 1980s, stands out for Sigma Corporation's design and innovation capabilities, optical performance, and the cult influence these products have had on amateur and professional photographers alike. The Mark II iterations of the lenses were first seen around 1988.

The 28mm 1:2.8 K_A-mount Mini-Wide II, the draw card, is fitted with an 'A' button, which, when set, allows the lens's aperture to be set by the camera. Aside from being used only in Fully Manual and Aperture-Priority with other legacy lenses, this makes it possible for the camera to be used in Shutter-Priority and Programmed Auto Exposure modes. The K_A-mount was introduced in 1983 with the launch of Pentax A and later, Pentax P series 35mm SLR cameras. The lenses are completely backward-compatible with the original K-mount system bodies.

On the 10MP Pentax K-m with the 1.5x CCD crop sensor, the Sigma Mini-Wide II 28mm 1:2.8 is equivalent to a 42mm prime on a 35mm full frame camera, close enough to the 43.3mm diagonal of the film frame. Though the focal length is slightly wider than a standard normal 50mm, yet tighter than a wide-angle 35mm (or when a 24mm is used in the same context), the focal length is often described as a 'sweet spot' for capturing a balanced view, allowing for some context while still isolating the subject. This focal length is also considered close to what the eye sees with natural and realistic perspective.

The 40mm focal length, just as well-suited for other photographic genres, including portraits, environmental portraits, aside from street photography, mimics what the eye sees with a perspective that is natural and realistic. The normally compact and lightweight lens is also easy on the go, and is a natural choice for many photographers who find it comfortable to work with for images that create a sense of realism, where the viewer feels like they are right there in the scene.

The Sigma Mini-Wide II 28mm 1:2.8, acknowledged for its portability, versatility, and good image quality, enjoys a rating of Sharpness (8.6), Aberrations (7.4), Bokeh (7.7), Handling (8.7), and Value (9.2) on PentaxForums. The K_A iteration has a plastic focus ring with rectangular pattern, is a 6-element, 6-group optical design with 6 blades, an aperture range from 1:2.8 to 1:22, a closest focusing distance of 0.22 meters (great for macros), a length of 43mm (50mm extended), takes 52mm filters, and weighs 210 grams.

Pentax K-m, K_A-mount Sigma Mini-Wide II 28mm 1:2.8

The advantage of the K_A Mount, when coupled to the Pentax K-m (and other Pentax bodies), is the versatility of a camera that can be used with all its exposure (PASM) and other custom shooting modes, and a lens with a focal length that will let you right into the context of a scene, with the ability still, to pick and single out the main subjects.

Pentax K-m, K_A-mount Sigma Mini-Wide II 28mm 1:2.8

p.s. Something to watch out for, when you bidding, is that while the Sigma Mini-Wide II 28mm 1:2.8 may be listed (in 2025) from as low as US$ 20 on the auction market, not many sellers specify what camera mount the lens is fitted with, neither do they show an image of the mount or the letters denoting the mount, which are often engraved or silk-screened on the lens barrel. Pentax K-m's, often available from as low as US$80, will normally require you to provide the 4x AA batteries and an SDHC card to get the camera up and running on your own.

Vintage Camera Marketplace by ImagingPixel

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Photo of the Day

Olympus E-500, Zuiko Digital 40-150mm 1:3.5~4.5

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Vintage Camera Marketplace by ImagingPixel

Malaysia's Online Marketplace for Vintage Film and Digital Cameras, Lenses,
and Camera Accessories. Follow ImagingPixel on Facebook, Pinterest, and X.

Photo of the Day

Olympus E-500, Zuiko Digital 40-150mm 1:3.5~4.5

<< Click on image for enlarged Lightbox display >>

Vintage Camera Marketplace by ImagingPixel

Malaysia's Online Marketplace for Vintage Film and Digital Cameras, Lenses,
and Camera Accessories. Follow ImagingPixel on Facebook, Pinterest, and X.

Photo of the Day

Olympus E-500, Zuiko Digital 40-150mm 1:3.5~4.5

<< Click on image for enlarged Lightbox display >>

Vintage Camera Marketplace by ImagingPixel

Malaysia's Online Marketplace for Vintage Film and Digital Cameras, Lenses,
and Camera Accessories. Follow ImagingPixel on Facebook, Pinterest, and X.