Hands down best lens for the money. While it's not Nikkor, it is also not over $1k. When my original lens broke after 4 years of abuse (I live in East Africa) I replaced it with a different Sigma. After not getting the same quality shots I bought this one again.

I've had the lens now for 1 week and I've put it thru some basic macro and non-macro shots in both low-light, ambient light and sunlight conditions. The lens has performed exceptional in all instances. Paired with my new Canon T4i camera I am getting amazing images in my opinion.

Outstanding macro; sharp images; excellent OS

zoom rotation is backwards from the other Sigma lenses I've used

If you're looking to upgrade from the 18-55 kit lens but don't want to break the bank then this is the right lens for you. It has a wider aperture of f/2.8-4, which means you'll get 50-200% more light to your camera and shallower DoF. 70mm definitely makes a difference over 55mm.

Since I was very pleased with the Sigma 30mm 1.4 EX and 180mm macro EX, I bought this lens second hand to see if it could replace my good old but dying EF 24-85 3.5-4.5 USM (own Canon 10-22, 70-200L f:4, 100-400L, 400L 5.6, 60 2.8 macro, 18-55 IS kitlens, use also 17-40L and 50 1.4).

fast and correct AF; good image stabilisation; sharp on wide angle at f:2.8; short focus distance

not sharp at f:4 on the long side; big and heavy; yellowish color tone compared to Canons

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.

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

Very good value / price ratio if you want to avoid weak zooms sold with high value bodies.

Useful range; Lightweight; Aberrations are not bothersome; Very sharp on the centre; Ideal for travelling

A bit soft on the edge at wide angle; So It is needed to close the diaph at at least 5.6 or raise the focal a little bit

This excellent lens has been used for portrait work and landscapes. I love the quick focus and feel of quality that it just oozes and I cannot find any fault in it. I would buy again and would certainly recommend it.

Durable; Great Features; Great Picture Quality; Lightweight; Simple Controls