No photo available for this lens
Production
1960 – 1989
Country
Japan
Optical
4-7 elements in 4-6 groups; Gauss/Tessar/Triplet/Telephoto design variants.
Updated
Feb 6, 2026
Sigma 28mm f2.8
Various Mounts · 28mm · f/2.8
AI-assisted · from real reviewsUpdated 6 Feb 2026
Overview
The Sigma 28mm f/2.8 in question is the Mini-Wide II, a compact manual-focus wide-angle prime that Sigma produced across the 1980s and early 1990s. It was offered in Pentax K-mount (in both P-KA and P-KM variants), M42, and other popular mounts of the era, targeting 35mm SLR shooters looking for an affordable wide-angle option. The lens was also rebranded and sold under the Promaster Spectrum name, making it a common find on the used market. According to the review database, some later K-mount versions include an 'A' setting for aperture automation on compatible Pentax bodies, though functionality may vary. Its appeal lies in being a budget-friendly, character-rich alternative to Pentax's own OEM 28mm primes. With a 97% recommendation rate among reviewers and an average price of around $41, it has developed a modest cult following as a cheap way to get a usable vintage wide-angle with a 'slightly vintage character.' No specific community nickname is evidenced beyond the 'Mini-Wide' family branding itself.
Verdict: The Sigma Mini-Wide II 28mm f/2.8 is a compact, affordable manual-focus wide-angle that delivers sharp centers from f/4–f/8 and a pleasing, slightly vintage character. It won't out-resolve Pentax's OEM 28mm primes, but for street, landscape, and close-up shooters seeking a characterful and inexpensive lens — whether native on Pentax DSLRs or adapted to mirrorless — it offers excellent value and earns its 97% recommendation.
Optical Character
Bokeh
Pleasant bokeh from thoughtful aperture design.
Color
Balanced color rendering, neutral with slight warmth.
Sharpness wide open
Good sharpness developing from f4 onwards, improving with stopping down.
Flare resistance
Moderate flare resistance with acceptable performance in backlit conditions.
Contrast
Good contrast with pleasant micro-contrast characteristics.
Vignetting
Mild vignetting wide open, reduces significantly by f2.8-f4.
Community Insights
What people love
- Excellent value — an average price around $41 with a 97% recommendation rate makes it an affordable entry into vintage wide-angle shooting.
- Sharp center rendering from f/4 to f/8, earning a high 8.6 sharpness rating.
- Compact and lightweight at around 210g, making it easy to carry for street and travel use.
- Smooth focus throw (~200°) that aids precise manual focusing (handling rated 8.7).
- Close-focus ability down to 22cm (1:4.5 magnification) for tight framing and environmental close-ups.
- Native K-mount fit on Pentax DSLRs and easy adaptation to mirrorless systems like Sony E, Canon RF, and Micro Four Thirds.
What people dislike
- Not as optically refined as Pentax's own OEM 28mm primes.
- The 'A' aperture automation setting on some versions may not function reliably on all bodies (functionality may vary).
Pro Tips
- Stop down to between f/4 and f/8 for the sharpest center results.
- Take advantage of the 22cm close-focus distance for environmental detail and close-up shots.
- Use the long ~200° focus throw for careful, precise manual focusing.
- Adapt it to mirrorless bodies (Sony E, Canon RF, MFT) if you want easy focus confirmation and to enjoy its vintage character.
Sources (3)
Web-grounded synthesissecondary
The Sigma 28mm f/2.8 in question is the Mini-Wide II, a compact manual-focus wide-angle prime that Sigma produced across the 1980s and early 1990s. It was offered in Pentax K-mount (in both P-KA and P-KM variants), M42, and other popular mounts of the era, targeting 35mm SLR shooters looking for an affordable wide-angle option. The lens was also rebranded and sold under the Promaster Spectrum name, making it a common find on the used market. According to the review database, some later K-mount versions include an 'A' setting for aperture automation on compatible Pentax bodies, though functionality may vary. Its appeal lies in being a budget-friendly, character-rich alternative to Pentax's own OEM 28mm primes. With a 97% recommendation rate among reviewers and an average price of around $41, it has developed a modest cult following as a cheap way to get a usable vintage wide-angle with a 'slightly vintage character.' No specific community nickname is evidenced beyond the 'Mini-Wide' family branding itself.
https://www.pentaxforums.com/userreviews/sigma-28mm-f2-8-mini-wide-ii.html
MFlenses ForumForum
Sigma's 28mm wide-angle lens available in multiple mounts. Sigma built reputation for quality optical design across various camera systems and focal lengths.
DPReview ForumForum
Sigma's 28mm wide-angle lens available in multiple mounts. Sigma built reputation for quality optical design across various camera systems and focal lengths.