Sigma 20mm F1.8 EX DG Aspherical RF Lens
The Sigma 20mm F1.8 is a 20mm f/1.8 lens designed for Canon EF, Nikon F, Sony A, Pentax K mount cameras. Check GearFocus for current availability, with buyer protection on every purchase.
Sigma 20mm F1.8 EX DG Aspherical RF Lens
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Lens Overview — Sigma 20mm F1.8
Key Features — Sigma 20mm F1.8
20mm F1.8 Prime: A fast wide-angle prime that combines a broad field of view with a large maximum aperture, useful for low-light and available-light shooting.
Full-Frame Coverage: Designed to cover the full-frame format, making it compatible with both full-frame and APS-C DSLR bodies across supported systems.
Aspherical Lens Element: Incorporates an aspherical element to reduce spherical aberration and distortion, which is particularly challenging to control at 20mm f/1.8.
Four-Mount Compatibility: Available in Canon EF, Nikon F, Sony A, and Pentax K mounts, covering a wide range of DSLR systems with a single lens design.
Autofocus Support: Offers both autofocus and manual focus operation, giving photographers flexibility across different shooting scenarios.
82mm Filter Thread: Large 82mm front filter thread accommodates the wide front element required by the f/1.8 aperture at this focal length.
Lens Specifications — Sigma 20mm F1.8
| Spec | Detail |
|---|---|
| Use Cases | Landscape, Astrophotography, Architecture, Creative Effects |
| Lens Type | Prime |
| Format | Full Frame |
| Zoom/Prime | Prime |
| Focal Length | 20mm |
| Maximum Aperture | f/1.8 |
| Camera System | DSLR |
| Lens Mount | Canon EF, Nikon F, Sony A, Pentax K |
| Autofocus | Yes |
| Focus Type | Auto, Manual |
| Image Stabilization | None |
| Filter Thread | 82mm |
Description — Sigma 20mm F1.8
The Sigma 20mm F1.8 EX DG is a prime wide-angle lens designed for full-frame DSLR cameras, with a fixed 20mm focal length and a maximum aperture of f/1.8. That wide aperture makes it well-suited to situations where light is limited or when a degree of background separation is desired at a wide focal length. The lens supports both autofocus and manual focus, offering flexibility across a range of shooting styles and subjects.
Mount options include Canon EF, Nikon F, Sony A, and Pentax K, so it can be paired with a broad selection of DSLR bodies. The filter thread is 82mm — a large size consistent with the demands of an f/1.8 wide-angle design — and the lens comes in at 520g, making it a solid but portable option for field use. Image stabilization is not present, so photographers should factor that into their decision-making for handheld work in low light.
Overall, it is a straightforward wide-angle prime with meaningful aperture performance and wide system compatibility.
Pros — Sigma 20mm F1.8
- ✓Fast f/1.8 maximum aperture enables shooting in low-light environments without sacrificing wide-angle framing
- ✓Full-frame coverage ensures compatibility with both full-frame and APS-C DSLR bodies
- ✓Broad mount compatibility — available in Canon EF, Nikon F, Sony A, and Pentax K — suits a wide range of DSLR users
Cons — Sigma 20mm F1.8
- ✗No image stabilization, which can be a drawback when shooting handheld in low light despite the wide aperture
- ✗82mm filter thread is large and means filters — polarizers, ND, etc. — will be more expensive and harder to source
- ✗Limited to DSLR mounts only; no native mirrorless mount options available in this product
Videos — Sigma 20mm F1.8
The 5 Sharpest 20mm Lenses I Ever Tested — Christopher Frost