Sigma 20mm f1.8 EX DG Aspherical - Lens

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Model Details

Autofocus wide angle lens made for Nikon F mount SLR cameras by Sigma. It has the AI ridge and AI-S indent but no bunny ear metering prongs so it will meter properly with all manual Nikon cameras (excluding the F, F2, and Nikkormats) and can be used with the advanced program modes of later models. It has a manual focus clutch and the autofocus requires a body with a built-in screw focus motor. Plastic/metal body available in black.

  • Sigma 20mm f1.8 EX DG Aspherical (13 elements, 11 groups)
  • Minimum focus distance: 0.2m
  • Aperture blades: 9
  • Size: 96 x 87 mm
  • Weight: 500g
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Nikon F

Nikon introduced their first SLR, the Nikon F, in 1959. Alongside it they unveiled a series of lenses and a new lens mount that would carry them to professional success for the next decades. To this day, all Nikon DSLRs use the Nikon F mount.

In the beginning, Nikon lenses communicated aperture information to the body using a metal coupling fork, affectionately known as "bunny ears". Soon after, Nikon began using a similar system that automatically told the camera the maximum aperture of the lens. This Automatic Indexing (AI) system stuck around for decades in lenses and is still found on Nikon's high-end professional DSLRs even though new lenses communicate this information electronically.

With only minor compatibility issues (don't use a pre-AI lens on AI bodies or modern digital cameras), Nikon F lenses and bodies are pretty much interchangeable.

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Sigma 20mm f1.8 EX DG Aspherical - Lens Availability & Price History
Date Sold SKU Quality Control Price Image
05 Jul 2025 T82142 € 233.54 Sigma 20mm f1.8 EX DG Aspherical - Lens Image
25 May 2023 T43179 € 189.00 Sigma 20mm f1.8 EX DG Aspherical - Lens Image
20 Jan 2023 T30596 € 199.00 Sigma 20mm f1.8 EX DG Aspherical - Lens Image
11 Jan 2023 T33560 € 182.80 Sigma 20mm f1.8 EX DG Aspherical - Lens Image