Simga’s 2012-234169 patent has calculations for 30mm f/2.8, 30mm f/2.5, 28mm f/2.8, 24mm f/2.8, 50mm f/2.8 and 55mm f/2.8 lenses designed for APS-C sized sensor. The interesting part is that the described lenses have built-in image stabilization. On few occasions in the past Sigma has made statements that they are not interested in developing a mirrorless interchangeable lens system camera. My guess is that those patents are for future DP compact camera models (like the DP1 and DP2). Here are some of the lens designs mentioned in the patent:
| Example | Focal length | Fno | Angle of view | Constitution | Aspheric surface | MOD | ELD glass |
|---|---|---|---|---|---|---|---|
| One | 30.83 | 2.89 | 50.49 | Seven elements in 5 groups | Two two-sided | 500mm | |
| Five | 30.77 | 2.47 | 50.43 | Eight elements in 6 groups | Two two-sided | 500mm | |
| Seven | 28.77 | 2.91 | 53.60 | Seven elements in 5 groups | Two two-sided | 500mm | |
| Eight | 36.83 | 2.92 | 42.87 | Seven elements in 5 groups | Two two-sided | 500mm | |
| Nine | 24.72 | 2.90 | 90.91 | Eight elements in 6 groups | Two two-sided | 500mm | One |
| Ten | 38.82 | 2.92 | 40.96 | Seven elements in 5 groups | Two two-sided | 500mm | |
| Twelve | 49.97 | 2.91 | 31.29 | 10 sheets in 7 groups | One one side | 800mm | One |
| 13 | 49.83 | 2.91 | 31.37 | 10 sheets in 7 groups | One one side | 800mm | Two |
| 14 | 54.15 | 2.91 | 28.99 | Eight elements in 6 groups | One one side | 800mm | One |
