Tamron's popular APS-C constant f/2.8 standard zoom with VC — covering 25.5-75mm equiv with stabilisation.
The Tamron SP AF 17-50mm f/2.8 XR Di II VC LD Aspherical (IF) (Model B005) was released in 2009 as the VC (Vibration Compensation) APS-C standard zoom for Canon EF-S, covering 27-80mm equivalent at constant f/2.8. Nineteen elements in 14 groups. Seven aperture blades. 72mm filter thread. At 570g. 0.29m MFD.
The optical design uses 19 elements in 14 groups. Seven aperture blades. The 72mm filter thread. At 570g the lens is moderate. Minimum focus distance of 0.29m (1:4.5 maximum magnification). VC (Vibration Compensation) built-in — Model B005 is the VC version; the non-VC version is Model A16. Variable aperture from f/2.8 (constant throughout zoom range). APS-C image circle (Di II designation).
The constant f/2.8 aperture through the 17-50mm range is the primary value proposition: indoor, event, and documentary photography on APS-C bodies at the standard zoom range with the exposure advantage of f/2.8 at all focal lengths. The VC provides stabilisation for handheld use. Di II confirms APS-C-only image circle — full-frame use will produce vignetting.
On the used market the Tamron SP 17-50mm f/2.8 VC (B005) is affordable as an APS-C constant f/2.8 standard zoom. Condition checks: VC engagement, AF response, 72mm front element for marks, zoom ring smoothness. Di II = APS-C only. Model B005 = VC version. Compatible with Canon EF-S APS-C bodies.