Quick answer
The Sigma 20mm f/1.8 EX DG is a ultra-wide prime lens covering 20mm at f/1.8 for the Sigma SA mount. Its fast maximum aperture helps in dim light and gives good subject separation.
About this lens
Sigma 20mm f/1.8 EX DG: a full-frame fast wide-angle prime lens with a 20mm focal length and a maximum aperture of f/1.8, made for Sigma SA mount cameras. The wide view suits landscapes, architecture and environmental shots.
Sigma 20mm f/1.8 EX DG specifications
What can you shoot with the Sigma 20mm f/1.8 EX DG?
At 20mm this is a ultra-wide prime, which typically suits:
- Landscapes and big skies
- Architecture and interiors
- Astrophotography and night skies
Its fast maximum aperture helps in dim light and gives good subject separation.
Full-frame equivalent and field of view
Calculated from the focal length and crop factor. Not measured.
| Sensor | Crop | Equivalent | Horizontal FOV | Diagonal FOV |
|---|---|---|---|---|
| Full frame | 1.0x | 20mm | 84° | 94.5° |
| APS-C | 1.5x | 30mm | 61.9° | 71.6° |
Frequently asked questions
What mount does the Sigma 20mm f/1.8 EX DG use?
It uses the Sigma SA mount, so it fits Sigma SA cameras directly.
What is the focal length of the Sigma 20mm f/1.8 EX DG?
It is a fixed 20mm lens with a maximum aperture of f/1.8. That makes it a ultra-wide lens.
Is the Sigma 20mm f/1.8 EX DG a prime or a zoom lens?
It is a prime lens with a fixed 20mm focal length. Primes usually open wider than zooms; this one opens to f/1.8.
What is the Sigma 20mm f/1.8 EX DG equivalent on a crop sensor?
On APS-C (1.5x crop) it frames like 30mm on full frame, with a 61.9° horizontal and 71.6° diagonal field of view. These figures are calculated from the focal length and crop factor.
