Features to look for…
Draw up a wish list for your ideal DX ultra-wide zoom
Compared with the natural field of human vision, a standard zoom lens gives a blinkered view.
For sweeping landscapes, you’ll often find that you can’t squeeze everything you want into the frame. The situation is worse when you’re shooting cramped interiors, where you can literally have your back against the wall and still not be able to shoehorn much into an image. The solution to the problem is an ultra-wide lens.
In this test we’re focusing on DX-format lenses (we’ll cover full-frame-friendly FX ones next month), so the 1.5x crop factor needs to be taken into account. A standard 18-55mm kit lens has an ‘effective’ zoom range of 2782.5mm. 50mm has always been considered a standard focal length for 35mm film cameras and fullframe D-SLRs, with 24mm, 28mm and 35mm being popular wideangle focal lengths, so an 18-55mm DX zoom lens covers the latter two of these options but sometimes it doesn’t stretch wide enough. A 10-20mm lens, for example, has an effective zoom range of 15-30mm, expanding the maximum angle of view to about 110 degrees, compared with about 75 degrees for an 18-55mm. That might not sound a lot extra but in practice the difference is enormous.
DX or don’t bother!
Using an FX lens on a DX camera is handy when you want to extend your reach. However, the situation is reversed when you’re trying to extend your angle of view. In most cases FX lenses’ longer focal lengths will fail to give you an ultra-wide viewing angle. The fullframe-compatible Sigma 12-24mm is an exception, but you’ll generally need to buy an ultra-wide lens that’s specifically designed for the DX format. Nikon and Tokina both use the ‘DX’ designation, whereas it’s ‘DC’ for Sigma and ‘Di II’ for Tamron. Full-frame lenses from these manufacturers are classified as ‘FX’, ‘DG’ and ‘Di’ respectively.
When you buy a lens, it’s worth weighing up the advantages and disadvantages of zoom and prime optics. Zoom lenses give more versatility, whereas prime lenses often deliver greater sharpness, wider available apertures and lower levels of distortions. Many photographers tend to use ultrawide lenses at or near their shortest focal length to really make the most of their potential. It’s a strange fact, then, that until recently there were no rectilinear ultra-wide prime lenses on the market for Nikon cameras – Samyang’s 10mm f/2.8 ED AS NCS CS prime lens should be on sale by the time this issue reaches you.
Rectilinear lenses aim to keep distortions to a minimum and, as far as possible, give a natural perspective. Another option is curvilinear or ‘fisheye’ lenses. These give an even greater angle of view, often as much as 180 degrees in both horizontal and vertical planes, but with extreme barrel distortion. They’re very specialised lenses and completely different to rectilinear optics, so we’re not covering them in this group test.
With an internal focus system, the front element doesn’t rotate during focusing, which is a bonus when using some types of filter. All the lenses in this test have internal focus systems.
A short minimum focal length is generally more important than the extent of the zoom range when you’re choosing a wide-angle lens.
Focus distance scale
A focus distance scale is especially useful on ultra-wide lenses for setting the hyperfocal distance (see Jargon Buster, below).
Another advantage of internal focus is that a more effective, petal-shaped hood can be used. This type of hood is supplied with each of the lenses, apart from the Sigma 8-16mm, which has a petal-shaped hood built in.
Most ultra-wide lenses have an attachment thread for fitting screw-in filters, but it’s not always the case, so do check.
All lenses in this test group have either ring-type ultrasonic autofocus or electric motors built in, so can autofocus on any Nikon D-SLR body.