Sigma Photo 20mm f/1.8 Lens

Light-gathering wide-angle lens for full-frame and APS-C cameras (Nikon mount)

  • Sigma Photo 20mm f/1.8 Lens

    Front (Nikon mount)


Our take on the Sigma Photo 20mm f/1.8 Lens

by Woody Sherman
Sigma Photo

Get the big picture — indoors

Say you're at the society event of the season, and you've been asked to document the event. The locale? A large, high-ceilinged hotel ballroom downtown, complete with a stage that houses a 19-piece big band. Oh, yeah, it's also pretty dark. How do you show people the scope of the place? How do you show people having fun without putting a flash unit in their faces?

Time to consider one of the most light-sensitive wide-angle lenses available today: the Sigma Photo 20mm f/1.8 lens. With its wide aperture that's perfect for low-lit interiors, you'll be snapping away in seconds, and, if you're shooting on a full-frame camera, everyone will get an idea of the grandeur and scale of what's going on. Even on an APS-C camera, you'll have a wide-angle 30-32mm focal length. Plus, the lens is perfect for landscapes and architectural photography as well, as you'll be able to fit a lot into one frame. Features like aspherical lens technology and a rear focusing system ensure that your images will have minimal color fringing and deliver solid image quality across the entire frame.

See Digital SLR Cameras that work with this item See more info on this item


  • Nikon bayonet mount
  • 20mm f/1.8 EX DG ASP RF wide-angle lens with 35mm equivalent of 30mm on Nikon cameras with APS-C sensors
    • NO built-in lens motor: NOT compatible with D40, D40x, D60, D3000, D5000
  • Super Multi-Layer Coating minimizes reflections and flare
  • light-gathering wide field of view is ideal for landscapes, exterior and interior architecture, and photojournalism
  • minimum focusing distance: 7.9"
  • constructed of 13 elements in 11 groups
  • filter size: 82mm
  • lens is 3.5" in diameter, 3-3/4" long
  • weight: 18.3 oz.
  • carrying case, lens hood, front and rear lens caps supplied
  • warranty: 4 years
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
Brand Compatibility Nikon
Image Stabilization No
Focal Length 20mm
Maximum Aperture f/1.8
Weight 18.3 ounces
Parts Warranty 4 Years
Labor Warranty 4 Years
Product Research
What's in the box?

Download owner's manual

  • Sigma 20mm f/1.8 EX DG ASP RF lens for Nikon
  • LCF-82 II lens cap (installed)
  • Rear lens cap (installed)
  • LH875-02 Lens hood
  • Soft padded case
  • Instructions
  • Warranty Card
  • Limited Warranty sheet

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.


Overview: The Sigma 20mm F1.8 EX DG Aspherical RF is a fast, ultra wide angle lens, designed to be used with full-frame cameras. It is a great lens for taking portraits, as well as for travel, weddings, and other events. The lens has the Nikon bayonet-mount.

Lens Hood: The Sigma 20mm lens includes a lens hood to help prevent stray light from entering the lens, causing flare, and to protect the lens from rain, snow, and dust. When not in use, the lens hood can be inverted and mounted onto the lens backwards for storage.

Focus Mode Switch: The lens features a two-way switch for setting the focus mode: AF (auto focus) or MF (manual focus).

Sigma Technology: The lens has the following Sigma technology built-in:

  • Aspherical Lens: Aspherical lenses are used for outstanding optical performance and to keep the lenses compact.
  • Super Multi-layer Coating: Sigma's own Super Multi-layer Coating suppresses lens flare and ghosting by preventing reflections within the lens.
  • Rounded Diaphragm: Using a rounded diaphragm instead of a polygonal shaped one produces pleasingly rounded out-of-focus light points when opened to near maximum aperture.
  • Rear Focusing System: Sigma uses a focusing system that moves the rear lens group, for high speed, silent focusing.


  • Lens Construction: 13 Elements in 11 Groups
  • Angle of View: 94.5°
  • Number of Diaphragm Blades: 9
  • Maximum Aperture: f/1.8
  • Minimum Aperture: f/22
  • Minimum Focusing Distance: 7.9"
  • Filter Size: 82mm
  • Maximum Magnifications: 1:4
  • Dimensions: Diameter=3.442", Length=3.731"
  • Weight: 18.3 ounces
See Digital SLR Cameras that work with this item
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Add accessories for the Sigma Photo 20mm f/1.8 Lens

Protect your lens from minor bumps and scratches. Lens filters can reduce reflections or glare, or increase contrast on your shots. See all categories & accessories

Hoya NXT Circular Polarizer Filter Polarizing filter for compatible cameras (82mm)
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Hoya NXT UV Filter Protective filter for compatible digital camera lenses (82mm)
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Hoya EVO Antistatic filter Circular polarizing filter (82mm)
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Hoya Alpha UV Filter Protective filter for compatible digital camera lenses (82mm)
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BlackRapid Lens Bling Identifier cap for bayonet-mount lenses (Nikon Skull)
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Hoya EVO Antistatic UV Filter UV filter for compatible digital camera lenses (82mm)
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Think Tank Photo Lens Changer 15 V2.0 Bag for small interchangeable lenses
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SideKick™ by LensPen® Touchscreen cleaning kit
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Nikon Micro Fiber Cleaning Cloth Cleaning cloth for delicate surfaces
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OSN Lens Pen Hurricane Blower Blower for camera lenses, filters, sensors and SLR mirrors
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Nikon Fog Eliminator 3-Pack Reusable cleaning cloth for fog resistance on lens surfaces
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For a more in-depth review and enhanced detailed information on the Sigma Photo 20mm f/1.8 Lens, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_366411NA/Sigma-Photo-20mm-f-1-8-Lens-Nikon-mount.html ).