Sigma 28-105mm f/2.8 ART: B&H Photo / Amazon / Adorama
Sigma has just had a new patent published (JP 2025-182227) which appears to contain the optical formula for the recently released 28-105mm F2.8 DG DN | Art, along with a few other fascinating sibling lenses that haven’t hit the market—yet.
The patent, published on December 15, 2025, describes a “Variable Magnification Optical System” designed to be compact while maintaining a large aperture (F2.8) and high zoom ratio. While one example matches the specs of the 28-105mm F2.8 almost perfectly, the other examples hint at alternative “standard zoom” concepts Sigma was exploring, including a wider 28-85mm and a portrait-focused 35-150mm.
Here is the breakdown of the optical formulas found in the patent:
Example 1: 28-105mm F2.8 (The Real World Lens)
This appears to be the optical recipe for the shipping Sigma 28-105mm F2.8 DG DN Art.
- Focal Length: 28.55 – 102.37 mm
- F-Number: 2.91 (F2.8)
- Half Angle of View: 77.11 – 22.75 degrees
- Image Height: 21.63 mm (Full Frame)
- Lens Length: 174.47 – 216.16 mm
Example 3: 28-85mm F2.8 (The Compact Alternative)
This is an interesting “what if” lens. Instead of reaching to 105mm, it trades telephoto reach for a more compact design. In the real world, this would likely be marketed as a 28-85mm F2.8. This would have been a direct competitor to classic standard zooms but with a unique range.
- Focal Length: 28.72 – 84.45 mm
- F-Number: 2.91 (F2.8)
- Half Angle of View: 76.47 – 28.04 degrees
- Lens Length: 161.89 – 206.15 mm
Example 6: 35-150mm F2.8 (The Portrait Specialist)
This looks like a direct competitor to the popular Tamron 35-150mm. It provides a highly versatile range for portrait and event photographers who want to avoid changing lenses, all while keeping that constant F2.8 aperture.
- Focal Length: 36.05 – 148.94 mm
- F-Number: 2.91 (F2.8)
- Half Angle of View: 64.53 – 16.07 degrees
- Lens Length: 199.15 – 249.15 mm
Takeaway It is common for manufacturers to patent multiple variations of a lens design during development. It seems Sigma decided the 28-105mm offered the best balance of size and versatility for the market, leaving the 28-85mm and 35-150mm on the drawing board—for now. Would you have preferred a 28-85mm F2.8 or a 35-150mm F2.8 over the 28-105mm? Let us know in the comments.
Follow SonyAddict on Facebook, Twitter, Instagram, and YouTube
Plus our owners’ groups
Sony a1 Owners Group
Sony a9 Owners Group
Sony a7 Owners Group