Sigma Lenses
This section comprises of the Sigma lenses that I have personally used at some point in time. My rating is based on the summary of factors. Such as quality of the pictures in terms of sharpness and contrast, usability, distortions and what it has been designed to do, i.e. macro.
ASPHERICAL	For better performance
DG	Lens coating is optimised to be used on digital SLRs
EX	Excellence (presumably better quality lenses)
HSM	HuperSonic motor for faster focusing
Wide angle
	Used	Rating	Comments
10-20mm F4-5.6 DG HSM	often	Excellent	Well built. Great for landscapes and tight spots. Performs well. Good colour reproduction.
17-35mm F2.8-4 EX	rarely	Very good	Well built. Works properly on film and digital SLRs. Images are softer at large apertures than by its Nikon counterpart. Color reproduction is very good.
24mm F1.8 EX DG ASPHERICAL MACRO	rarely	Very good	Pro-built. Fast auto-focus. Produces good sharpness only when it reaches f5.6 aperture. That defeats the purpose of a faster lens. A 24mm f2.8 Nikon would probably be a better deal.