Tried to save some money by buying an after market product. Did not take go pictures when lens was entended out to 70mm. Built cheap. You get what you pay for. Taking back. Going to get the actual Canon lens.

[...] I HAVE TRIED THIS LENS ON MY NIKON D300S AND WAS DISAPPOINTED WITH THE PICTURE QUALITY NOT TO MENTION THE COST OF THIS LENS.

Durable; Well Made

Poor picture quality

Fits the bill as the perfect walk around lens for my 77D. Image quality is very good with nice color rendition and weighs half as much as the 24-105 f/4L. If you shoot both full frame and crop sensor I say get this lens for your crop sensor camera and leave your 24-105 f/4L on you full frame camera.

I tested the lens taking many pictures with my D7000 and D600. The pictures were not as good as I expected

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.

I bought this lens primarily for low light use since I like to shoot at night. So far so good. I have not critically tested the sharpness but casual observation indicate good resolution although not as good as the Nikon lenses. Mechanically it works great.

Consistent Output; Durable; Easily Interchangeable; Fast / accurate auto-focus; Lightweight; Strong Construction

The 17-70mm f2.8-4.5 DC Macro AF (Auto Focus) is Sigma's first digital only macro lens.

Sharp, fast, contrasty; Bargain price for its overall capabilities

Drag on the manual focus ring

This is a fantastic walk-about and general purpose lens for cropped sensor Digital SLRs -certainly for value for money, it's unbeatable. It does not feel cheap, the build quality is good, it feels sturdy and it comes with a zoom lock, which prevents the zoom sliding out when walking about.

Superb value for money; great image quality; good construction; high maximum aperture

Noticable barrel distortion at 17mm

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

Very versatile range, and macro. Fast, and very sharp, especially on a tripod. I like the zoom lock and the feel of this lens is solid.