Digging through the vast array of optics out there to find the best Sigma ultra wide-angle lenses under $500 can be quite a chore. When it comes to the widest of the wide of lenses, which generally means glass under 10-12mm, the options are far fewer.
Sigma has put all their widest, i.e. fisheye lens offerings, in their high-end optics camp, which means today we are sticking with regular viewpoint options. And those examples with a slightly more narrow view.
This means that the lenses we have on offer today are still affordable options and within budget while still being on the wide side. These examples still provide very wide-angle views of the world.
1. Sigma 10-20mm f/3.5 EX DC HSM (Overall Winner)

As we need to go as wide-angle as possible today, its the Sigma 10-20mm f/3.5 EX DC HSM that covers all our needs. This is a good lens, well under our budget, with top-draw optics to cover everything from landscapes to architectural work.
When this lens is strapped to an APS-C-format camera, it provides a 16-32mm equivalent focal length. The constant f/3.5 aperture may not seem the widest in the world, but on an ultra-wide lens, it can still provide extremely low shutter speeds, while still working well in low light.
Four aspherical elements and a super multi-layer coating have been added to increase image quality, while the Hypersonic autofocus motor is respectably quick and quiet in use. Considering this lens’ nominal asking price, it provides wonderful image quality in a very useful package.
2. Sigma 16mm f/1.4 DC DN Contemporary

If you need the ultimate in image quality at a respectably cheap price point, you cannot do better than the Sigma 16mm f/1.4 DC DN Contemporary. In all honesty, this lens is sharper and faster than the zoom above, but it doesn’t go as wide-angle, which is our main criteria today. However, if you don’t mind the more narrow view, especially on crop sensor cameras providing 24mm, this is a wonderful lens for the money.
Internally, the lens comprises of two Special Low Dispersion, three F Low Dispersion, and two aspherical elements, plus a stepping autofocus motor which is fast and quiet enough for both stills and video work.
The f/1.4 aperture works wonderfully in very low light conditions and for a wide-angle lens, it even produces professional-level bokeh. If you need a very wide-angle lens that doesn’t cost the earth and is super sharp, the 16mm f/1.4 DC DN Contemporary is a great choice.
3. Sigma 18-200mm f/3.5-6.3 DC Macro OS HSM Contemporary

Generally speaking, when we are working with a budget of under $500, we usually want a lens that can do a bit of everything. This is where the 18-200mm f/3.5-6.3 DC Macro slots in, providing a 28.8-320mm viewpoint on crop sensor cameras.
To cover such a wide focal range, the lens features four Special Low Dispersion and three aspherical elements to reduce lens anomalies, along with a super multi-layer coating to reduce the likes of lens flare and ghosting.
Also thrown into the mix is a macro mode with a 1:3 reproduction ratio and an optical stabilizer to reduce hand-held camera shake. The lens also features a zoom lock switch to keep everything at one particular focal length.
The 18-200mm f/3.5-6.3 DC Macro covers a lot of bases for the money, and while it may not be the best macro lens in the world, it does provide respectable sharpness and image quality throughout the focal range. Essentially, if you need a zoom lens that travels from the wide-angle to medium telephoto zone with a smattering of other facilities, the 18-200mm is a good choice.
4. Sigma 18-300mm f/3.5-6.3 DC Macro OS HSM Contemporary (Budget Winner)

Another do-it-all lens with a slightly longer reach is the Sigma 18-300mm f/3.5-6.3. This lens goes as wide as the option above but also provides a 28.8-480mm viewpoint on crop sensor cameras. This range gives enough scope for everything from landscape views to even wildlife photography.
This type of range needs a fair degree of optical correction, which has been covered with the inclusion of one Special Low Dispersion, four F Low Dispersion, and three aspherical elements. The glass is wrapped around a total arrangement of 17 elements in 13 groups.
Just like the lens above, the 18-300mm f/3.5-6.3 has a macro mode with a 1:3 reproduction ratio. This mode may not fill the frame with a subject like a 1:1 ratio lens, but it is perfectly adequate for those odd occasions where you want to capture small subjects.
This lens features an optical stabilizer system, which is most needed at the longest focal lengths. Additionally, as the lens has a variable aperture, the stabilization system allows you to venture into low-light conditions without cranking up the ISO levels too high.
When evaluating a lens of this type, there’s always the consideration of what you’re getting in exchange for the money. This lens is respectably sharp where it counts with the best results coming in at the wide-to-medium range as the stabilization system bobs around constantly at the longer focal lengths.
This lens works best for someone who wants a more rounded solution that covers the most optical bases. The optics produce minimal anomalies, like chromatic aberration and lens distortion, while also resulting in a good degree of color and contrast for the price point.
Summary of the Sigma Ultra Wide-Angle Lenses Under $500
As originally stated, if you need the widest angle views possible, you will either have to spend a bit more or venture into other third-party fisheye lens solutions.
A fisheye lens can provide a nearly 180-degree view of the world, but it also comes with a few caveats. Lines at the edge of the frame will be distorted and not everybody’s into the bulbous look, which is a trademark of every fisheye lens.
All this means that examples like the Sigma 10-20mm f/3.5 and the 16mm f/1.4 may provide a slightly more narrow view, but in exchange, they both have loads of versatility and wonderful optical qualities for the price.
If you need the most rounded wide-angle options, then the zoom lens is a good choice, but if you want to put all your eggs in one basket, aka one focal length, you can’t go wrong with the 16mm f/1.4 prime lens for its ultimate sharpness and very wide f/1.4 aperture.