Sigma 10-20mm f4-5.6

For the price (one of the cheapest in any mount) and features (including a moderately fast maximum aperture of f4 at the widest angle - where you'd most likely use the lens), this is in my opinion the best value wide-angle lens for APS-C sized sensor cameras at the moment.

   The lens is very sharp at the centre (even wide open) and pretty sharp in places but is somewhat blurred frustratingly, in other areas, including the corners. I used the word 'other' because it appears sharp only at seemingly non-logical parts of the frame. This might vary by lens copy however.

   Having said that, when stopped down to between f5.6 and f8, it is noticeably sharper proportionately in all areas. So the sharpness of the lens when stopped down is where this lens shines for me, especially at a price point that makes it very competitive to its rivals.

   Because I shoot with this lens stopped down mostly, I find it works best for landscape work. However, it is possible to get very creative shots in interiors, because of the distortion with close-up objects and simply because of how wide the lens goes. If you do a lot of low-light work, then something with a faster aperture like the Tokina 11-16mm f2.8 would serve you better.

   As the lens is so wide it is a good idea to familiarise yourself with the strengths and weaknesses of such a lens, which include the distortion, which can be a blessing or a sin and the almost necessity to have some sort of foreground interest in the frame.

   This lens is criticised for flare and I agree with that but it is quite alright to change the composition slightly so the Sun is blocked or out of the frame. So for me flare is not too much of an issue, as long as I'm aware of it.

   Build quality is superb, with a very solid feel to the lens and the front of the lens does not rotate or change length when focussing. Also the manual focus and zoom rings are smooth to turn but at the same time resistant enough to avoid slipping. The lens is pretty heavy though.

   I think the range is ideal - it is very wide obviously but the long end of 20mm just overlaps your typical kit zoom so there is no gap in focal lengths.