• Super Multi Coating reduces flare and ghosting that tends to occur when using digital SLR cameras
• High performance medium telephoto macro lens optimized for digital cameras
• Lens Construction - 11 Elements in 10 Groups
• 12.3 (31.3cm) Minimum Focusing Distance
• Dimensions - Diameter 2.9 x Length 3.8 (74x97.5mm)

The Sigma 257-306 105mm F2.8 EX DG Macro lens for Canon SLR mount is very suitable for taking pictures in nature, while it uses natural light conditions or flash. The greater working distance of this lens is very advantageous when taking the picture of a flower among the branches or an insect. The narrow angle of view is a great aid for simplifying backgrounds and shallow depth of field makes it easier to handle the composition. This lens would have an equivalent field of view of a 178mm telephoto macro lens on a digital SLR camera. This new medium telephoto macro lens employs a new design concept for digital SLR cameras. Its power layout produces an excellent optical performance and also reduces flare and ghost. This lens is designed to reduce the influence of harmful light caused by reflections from the digital image sensor. A screw-in hood is included, for convenient use of circular polarizing filters. It is possible to attach a 77mm filter in front of the lens hood. This lens also incorporates a Dual Focus (DF) system that is designed to make the lens easy to hold during auto focusing. The large focus ring offers smooth and positive action whilst focusing manually. Weight - 16.1 ounces (457 grams)

Shipped on time.
Great Product.
Excellent price.
Will buy from them again and again.

I bought this lens in December 2007 and just start to use it from this March. The picture quality is good but needs a lot of light and contrast for the AF to work.
In June, during an outing, one of the element (glass) fell out of it's holding socket and the lens would not retract to below 1:3.
Since I bought this lens in gray market, so that there's no warranty. I just open the lens and fix it myself, works fine.
However, the story did not end there. Just yesterday, during some test shots at home, the lens would not focus and the motor is trying but could not move. I switch to Manual but the focusing ring would not stay at M mode and I can turn the ring freely and it won't adjust the focus (in AF mode, the ring supposed to have resistence from the motor gear and you should not try to adjust manually).
If you are thinking of buying this lens, make sure to buy it with warranty or better yet extended warranty.

This is a very fun lens with great color and clarity. This stays on my camera 90% of the time and with f/2.8 it's still useful indoors. Although I think the lens I received may have been faulty the only problem is the auto focus. I've had this lens for only about 6 months and the AF is pretty much shot. It constantly searches no matter what light condition I'm in and it never comes out clear (when using AF). The auto focus also sticks halfway so I've got to give it the extra push, but to save the hassle it's just better to use manual focus from now on. Like I said, I think I've received a faulty lens, but I have read on quite a few Sigma reviews that their auto focus is not very dependable. I love this lens I just wish I could have the luxury of good auto focus like Canon's USM.

Pros:
Very good image quality
Very solid build
Very sharp when used with tripod
Good price

Cons:
Extremely slow autofocus, AI servo mode is useless
Extends front element during focusing
Slight CA detected in some images
Not very useful in handheld mode unless lighting is very good (full sunlight)

I just love working with this macro lens and my Canon digital SLR XTi. Perfect for my dental, intraoral photography needs.