The Sigma AF 17-70mm f/2.8-4 DC HSM OS is a fairly obvious candidate for budget oriented consumers. It may not reach stellar performance levels but the resolution figures are generally very decent.

Yes, I would recommend this to a friend

Consistent Output; Durable; Easily Interchangeable; Rugged; Sharp Focus; Strong Construction

Slight vignette

I purchased this lens as an upgrade for my Canon 400D 17-55mm kit lens about 6 months ago. I am glad I did! It’s a little gem, that seems to get over looked. I did plenty of research before parting with my cash, and had my eye on the Canon 17-85mm EFS.

Sigma's 17-70mm f/2.8-4 DC Macro OS HSM lens is an upgrade to the AF 17-70mm f/2.8-4.5 DC Macro lens released in 2006. Designed for the smaller imaging circle of cameras with APS-C sized sensors, it is slightly larger and heavier than its predecessor and has a more complex optical construction.

You want an affordable general-purpose lens to replace a standard kit lens, You'd like a lens that requires no readjustment when you fit polarisers and graduated filters; Don't buy this lens if, You require a lens with excellent flatness of field and edge-to-edge sharpness, You need true macro...

This digital-only lens boasts excellent performance, Optical Stabilisation and a rock bottom price tag - so is there anything not to like?

Great all-round lens

Non-internal focusing

With so much to talk about in this lens it would be easy to miss something important, such as the fact that it offers a bright f/2.8 aperture at 17mm. This is an amazing achievement that is all the more remarkable given the zoom's 4.1x focal-length range.

Great all-round lens

Non-internal focusing

An upgrade of Sigma's digital-only macro lens (the 17–70mm f/2.8–4.5), this large-aperture standard zoom ($450, street) adds a tad more speed, another aspheric element (for a total of three), on-board image stabilization, and several ounces more in weight.

Yes, I would recommend this to a friend

Easily Interchangeable; Fast / accurate auto-focus; Nice Bokeh

Heavy

I bought this lens as a replacement to a Nikon 17-55 F 2.8 damaged irreparably; so consider myself very critical. Features Its a moderately fast 17-70 F2.8 – F4 Variable aperture DX or APS Zoom with Image Stabilisation (OS) and good close focusing ability.

Versatile and useful Zoom Range 17-70; Image stabilization; Fast at wide angle; Smooth bokeh; Close focus

Annoying Manual Focus switch; A touch soft at wide apertures; No weather sealing

A compact standard zoom for APS-C digital SLRs with a fast variable aperture, optical stabilisation, a silent focusing motor and an interesting close focus capability.

Excellent optical performance; Decent build quality; Effective optical stabiliser; Close focus ability

Focus ring cannot be disengaged during AF