Best Rated Sigma DSLR Lenses (For Canon SLRs)

Sigma Canon DC Lenses = were specifically designed for Digital SLRs with APS-C sized imagers (not full frame). These include: Digital Rebels XT, XTi, XS, XSi, T1i, T2i, T3i, T4i and Canon EOS 7d, 20d, 30d, 40d and 50d. SLRs with APS-C size imagers have a conversion factor of 1.6 applied to the lens focal length.

Sigma Canon DG Lenses = were specifically designed for Digital SLRs with full frame (35mm film) sized imagers and can also be used with APS-C sized imager SLRs (apply 1.6x to the focal length).
APS-C Imager = This imager is smaller than a Full Frame imager. Lenses used on SLRs with APS-C imagers have a focal length about 1.6x that of full frame imagers. This means that the telephoto end of the lens will be greater. New digital lenses have been developed for these type of SLRs.
Full Frame Imager = This means that the imaging sensor is the same size as 35mm film. 35mm lenses will operate on these DSLRs with the same focal lengths as they do on 35mm film cameras.
OS = This denotes that this lens has built-in optical image stabilization to negate vibration and camera shake that can make pictures blurry. This is especially important with telephoto lenses where camera shake is magnified.
HSM = This lens has a Hypersonic Motor – This is a special type of ultrasonic motor within a modern autofocus sigma lens that allows for extremely quick focus shifts with very little sound. (Non HSM lenses can be slow and noisy). This is similar to Canon’s USM.
IF = This lens has an internal focusing. To ensure stability in focusing, this lens moves the inner lens group or groups without changing the lens’ physical length.
RF = This lens has rear focusing. This lens is equipped with a system that moves the rear lens group for highspeed, silent focusing.
DF = The DF (Dual Focus) system disengages the linkage between the internal focusing mechanism and outer focusing ring when the focusing ring is moved to the AF position.
EX = This denotes that this lens is a high quality professional lens
APO = This lens is an Apochromatic Lens. keeps color aberration to a minimum, using Special Low Dispersion glass.
ASP = This lens is an Aspherical Lens. This lens provides high optical performance while maintaining a compact size.
ELD = Extraordinary Low Dispersion glass used for superior sharpness, contrast, and color
Macro = This lens has the capability to focus up close to subjects.