The Sigma 20mm f/1.8 EX DG lens is a wide-angle prime lens designed for full-frame and APS-C digital SLRs. It was announced on December 1, 2000, and remains popular for its combination of good build quality, a fast aperture of f/1.8, and decent optics.
Here are some key features of the lens:
Focal Length: 20mm
Maximum Aperture: f/1.8
Minimum Aperture: f/22
Minimum Focus Distance: 20cm (7.87 inches)
Weight: 520g (1.15 lbs)
Length: 90mm (3.52 inches)
Lens Mounts: Canon EF, Nikon F (FX), Pentax KAF, Sigma SA Bayonet, Sony/Minolta Alpha.
The lens incorporates a Dual-Focus (DF) mechanism, which makes it easy to hold the lens since the focusing ring does not rotate during auto-focus. It also provides adequate focusing torque during manual focusing. The use of aspherical lens elements in both the front and rear lens groups effectively compensates for distortion, spherical aberration, and astigmatism.
However, the lens has some drawbacks. It is known for having strong vignetting, especially at f/1.8, and the corners can be quite soft at wider apertures. The lens is sharp in the center at f/4 and even sharper at f/5.6.
Overall, the Sigma 20mm f/1.8 EX DG lens is a good option for those looking for a wide-angle prime lens with a fast aperture, but it may not be the best choice for those who require edge-to-edge sharpness at wider apertures
Wide-Angle Delight: The Sigma 20mm f/1.8 EX DG lens was announced on December 1, 2000, and is designed for both full-frame and APS-C digital SLRs. It's known for its good build quality, a fast aperture of f/1.8, and decent optics.
Dual-Focus Mechanism: The lens incorporates a Dual-Focus (DF) mechanism. This feature ensures that the focusing ring does not rotate during auto-focus, making it easier to hold the lens. It also provides adequate focusing torque during manual focusing.
Aspherical Elements: The use of aspherical lens elements in both the front and rear lens groups helps to effectively compensate for distortion, spherical aberration, and astigmatism, contributing to better image quality.
Vignetting and Sharpness: While the lens has strong vignetting, especially at f/1.8, and the corners can be quite soft at wider apertures, it is sharp in the center at f/4 and even sharper at f/5.6. So, it may not be the best choice for edge-to-edge sharpness at wider apertures.
Versatile Mounts: The Sigma 20mm f/1.8 EX DG lens is available in various mounts, including Canon EF, Nikon F (FX), Pentax KAF, Sigma SA Bayonet, and Sony/Minolta Alpha, making it compatible with a wide range of cameras.
Compact and Lightweight: With a weight of 520g (1.15 lbs) and a length of 90mm (3.52 inches), it's relatively compact and lightweight for a wide-angle prime lens.
Picked this lens up today for $50 US. A steal.
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