Sigma 10-20 EX HSM

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Sigma 10-20mm f:4-5,6 EX DC

Sigma presented the Wide-angle Zoom 10-20 f4-5.6 EX HSM DC in the beginning of 2006, entering to be part of the lens groups dedicated to the digital world sensors in the 10mm range. This lens is designed to be used in APS-C sensor digital cameras, since it can not be used in the 35mm analogical format: the results would be disastrous, showing a strong vignetting throughout all its zoom range. The Sigma 10-20mm DC would be equal at a 15-30mm in a Nikon DX sensor and at a 16-32mm in a Canon APS-C sensor. It is very appropriate for interiors photography, landscapes and astonishing photos.

The lens has 14 elements in 10 groups and includes 3 SLD glasses and 3 aspherical elements (one molded and two hybrid-type) that offer an excellent distortion correction as well as all aberration types.

This Sigma is equipped with a internal focus system, enhanced with the HSM system, what provides a very quick and silent autofocus, and the same way allows a full time manual override. It has a 6 blade aperture mechanism and it weighs about 470 grams.

It has a minimum focus distance of 24cm in all the range and the covering angle varies from 102,4º (10mm) to 63,8 (20mm), and it is the bigger aperture angle zoom in this sector. The Canon EF-S 10-22 has a maximum angle of 97º and Nikon 12-24 AFS DX has 99º (in spite of being a 12mm).

The front element non rotative allows the use of polarizer filters without problems, as well as a petal-type hood. It hardly changes size when using the zoom.

The distortion at 10mm is, surprisingly, almost nonexistent, allowing to photograph landscapes with almost right horizons, anyway, if we maintain the wide-angle photography doctrine inside its parameters. Starting at 14mm the lens shows pincushion distortion and it is more or less as its partners.

The vignetting is the typical for this type of zooms and it is about around 1 EV in the worst cases, that is to say, at 10mm and f4, something that you can solve if we have Photoshop CS2, using: filter / distortion / lens correction, and we can fix vignetting easily.

The lens resolution can be considered as good to very good in almost all the situations. In general lines, the resolution in the center is excellent and stays as good in the corners, improving enough at medium aperture settings.

Why buy Sigma and not Nikon or Canon?, well, simply for a price question; the quality difference among the three lens is not so much, it is not proportionally indicative. The Nikon 12-24mm f4 AFS DX costs 1.149 Euros, the Canon EF-S 10-22mm f3.5-4.5 USM costs 909 Euros and Sigma 10-20mm EX f4-5.6 HSM DC costs 567 Euros. And I can be sure that the other ones double price doesn't mean double quality, although in some certain occasions, it would be worthwhile to acquire a Nikon or a Canon, but that is another question.

Some test images taken with this lens:

Nikon D50 + Sigma 10-20 EX HSM. Shoot data: 1/500 and f11 ISO 200

Nikon D50 + Sigma 10-20 EX HSM. Shoot data: 1/400 and f10 ISO 200

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