Product Description

This super-wide-angle lens is ensured minimal light-fall-off with superior peripheral brightness. The iris diaphragm has 9 diaphragm blades to obtain beautiful out of focus images in the foreground and background. This is an ideal DG lens optimized Digital SLR camera.The minimum focusing distance of this lens is 20cm (7.9 inch) and it has maximum magnification of 1: 4 with fast F 1.8 maximum aperture. The minimum focusing distance of 20cm (7.9 inch) and 94.5? angle of view allow close up photography surrounding the photographic subject.The lens incorporates Dual-Focus (DF) mechanism. It is easy to hold the lens, since the focusing ring does not rotate during auto-focus, yet it provides adequate focusing torque of the focusing ring during manual focusing of the lens. The rear focus system eliminates the need for the front of the lens to rotate, thus allowing the use of a "Petal-type hood", which is superior light blocking effect.The use of aspherical lens elements in both of the front and rear lens groups effectively compensates for distortion, spherical aberration and astigmatism.

Product Details

• Brand: Sigma
• Model: B00005RKSL
• Dimensions: 3.00 pounds

Features

• Lens Construction: 13 Elements in 11 Groups Angle of View: 94.5 degrees Number of Diaphragm Blades:

Amazon.com Product Description
The Sigma 20mm super-wide-angle lens provides minimal light falloff and superior peripheral brightness, helping you take masterful landscape shots or large family portraits. The lens is equipped with a high-quality Dual-Focus (DF) mechanism. The DF system makes it easy to hold the lens, as the focusing ring doesn't rotate during autofocus. At the same time, however, the lens still provides adequate torque for manual focusing operations. By incorporating a rear focusing system, Sigma made the lens compatible with petal-type hoods, which offer superior light blocking effects. In addition, the lens offers a super multi coating that reduces the flare and ghosting that often occurs in digital cameras, along with nine diaphragm blades to help you obtain beautiful out-of-focus images in the foreground and background. Other features include a minimum focusing distance of 7.9 inches, a maximum magnification ratio of 1:4, aspherical lens elements in the front and rear lens groups to compensate for distortion and spherical aberration, and a 94.5-degree angle of view.

Specifications

• Focal length: 20mm
• Maximum aperture: f/1.8
• Lens construction: 13 elements in 11 groups
• Angle of view: 94.5 degrees
• Number of diaphragm blades: 9
• Minimum aperture: f/22
• Minimum focusing distance: 7.9 inches
• Maximum magnification: 1:4
• Filter size: 82mm
• Mount: Nikon
• Dimensions: 3.5 inches in diameter and 3.5 inches long
• Weight: 18.3 ounces
• Warranty: 1 year

Customer Reviews

Wonderful!!!
This is one of my all time favorite lenses. I usually just leave it mounted. It's fast max aperture and close focusing make it indispensable to me. Check it out--it focuses to within and inch of the front lens element!

I've had one issue-it recently self destructed. The iris folded over itself. It's inside the four year warranty (and damn near the end I might add) so it's been fixed and is currently on the way back to me from sigma as I type this. I'm disappointed it failed, but considering the frame count and price, I can't really complain.

I paid not much more than $300 for this lens new almost 4 years ago, and I'd gladly pay twice that for the shots this lens has gotten me. I've taken it out in the rain and snow and hail and the fact that it failed only recently attests to the build of this fine lens.

Buy it while they still make it! I may buy a backup soon for this reason.

Fantastic bokeh
I picked this up just over a month ago when I got my D90. It has been on my camera more than my 18-200mm VR. I truly love this lens. The bokeh is amazing. It is a touch soft but that is easily fixed with software. The low light shots always surprise me on how well they look even over my Nikon 50mm 1.8. This is one lens I will not regret buying.

Should have been smarter
A 20mm f1.8 prime for $400.00? What was I thinking? At f1.8 the lens is unacceptably soft. Better at 2.8, but still not great. It's not until f4 that the Sigma matched the sharpness of my Nikon 17-55 f2.8 zoom. A full stop slower! This begs the question - what is the point of having this lens if it's soft until f4? Answer - no point at all. Sending it straight back.