Sigma 20mm f/1.8 EX DG RF Aspherical Lens

Already own this?

This item is in your gearlist!

Key Features

  • 20mm focal length
  • 30mm equivalent focal length on APS-C cameras, 32mm equivalent focal length on Canon APS-C cameras
  • F1.8 maximum aperture; F22 minimum
  • 82mm filters
  • 0.20m/7.87" minimum focus
  • Available in Canon EF, Nikon F (FX), Pentax KAF, Sony Alpha, Sigma SA mounts

Product Description

The Sigma 20mm F1.8 EX DG Aspherical Macro is a standard wide-angle lens for full-frame and APS-C digital SLRs. Although not a new lens, it remains popular for its combination of good build quality, a usefully fast aperture of F1.8 and decent optics. You don't get Sigma's HSM ultrasonic-type autofocus motor but a clever manual/auto focus clutch gives quick access to manual focus if you need to fine-tune.


Principal specifications
Lens type Prime lens
Max Format size 35mm FF
Focal length 20 mm
Image stabilisation No
Lens mount Canon EF, Nikon F (FX), Pentax KAF, Sigma SA Bayonet, Sony/Minolta Alpha
Maximum aperture F1.8
Minimum aperture F22.0
Aperture ring Yes
Number of diaphragm blades 9
Elements 13
Groups 11
Special elements / coatings 2 aspherical elements
Minimum focus 0.20 m (7.87)
Autofocus Yes
Full time manual Yes
Focus method Rear
Focus notes dual focus mechanism
Distance scale Yes
DoF scale Yes
Weight 520 g (1.15 lb)
Diameter 89 mm (3.49)
Length 90 mm (3.52)
Colour Black
Filter thread 82 mm
Hood supplied Yes
Hood product code petal type hood
Tripod collar No


User Reviews

4.125 out of 5 stars
  • xtranch, Jan 17, 2012 GMT:
    great lens for the price

    This lens is great for landscapes, very sharp, even good in the corners where I use it--on a tripod at f5.6-8. the build is not superior but adequate. The performance is as good as much more expensive lenses.

    Continue Reading

  • martinlens, Sep 29, 2011 GMT:
    Sigma 20mm F 1.8

    This is a very good lens,its at 1.8 wide open already very sharp.ofcourse it has light falloff in the corners bud thats something every fast wideangle lens 4.0 this problem has solfed.Ate F 5.6 itz RAZOR SHARP from edge to edge. Forget all the other revieuws,I have one myself, i now what i am talking aboud.Other revieuw websites always debunk Sigma because they are sponserd by Canon and Nikon too do so and too promote their own products.I defenily advies too buy this lens.,itz very ...

    Continue Reading

  • erick4x4, Mar 28, 2011 GMT:
    Great lens for what it is

    This lens is a mixed bag for sure. For what it is its pretty impressive. On Full Frame its pretty much one of if not "the" fastest ultra wide angle lens. I would not really want to use this on crop sensor cameras, its not worth the trade offs. This lens has the old manual focus clutch, switch system, which I have never liked. Further the ring is so big its really easy to pick it up and change from MF to AF. At 1.8 the edges aren't great, but the center is. But hey it can do 1.8 what else can? ...

    Continue Reading

  • doracapi, Nov 26, 2014 GMT:
    Good wide angle lens

    Very good for close up at f1,8, very soft corners and some CA, better at f2,8. Central resolution and acutance  are excellent from f4 to f8, corners are good from f5,6 to f11. CA and distortion are low.Acutance is very good. Resolution is low at f1,8 and f2,8. Vignetting is important up to f2,8. AF is good.

    Continue Reading

Warranty Information

"Beginning July 1, 2013, all brand new Sigma Products purchased from authorized Sigma dealers are covered under the 1 year America warranty (North and South America) and U.S.A. extended warranties for a period of three (3) years against defects in manufacturing and workmanship only. Your warranty period begins the day you purchase your Sigma camera, lens and/or flash and runs for a total period of four years from that date (please refer to the warranty policy included with your product)."

Go to Sigma's warranty registration page for more information and to register your Sigma product. DPReview GearShop is an authorized Sigma dealer in the United States.

  • Please enable JavaScript. GearShop is designed to work with JavaScript enabled. You may not be able to use our site properly if it's disabled in your browser's settings.