মঙ্গলবার, ১৬ জুলাই, ২০১৩

Canon EF 135mm f/2L USM


The Canon EF 135mm f/2L USM ($1,089 direct) is a prime lens for Canon cameras with a focal length that is traditionally useful for portraiture. Of course, you won't be limited to that purpose when shooting with the lens; it does double duty as a medium-telephoto lens, and a sharp one at that. It's not a perfect lens?there's no optical stabilization. Still, the lens is quite sharp, even at the edges, and focuses with impressive speed.

We didn't like it quite as much as another 135mm lens that earned our Editors' Choice award, the Carl Zeiss Apo Sonnar T* 2/135, which is sold in versions for use with Canon and Nikon cameras. That lens is, from what we could tell, just about perfect optically, and even avoids the green and purple highlights that show up in the out-of-focus areas of images shot with this Canon EF 135mm lens. But the Zeiss lens is manual focus only, and more expensive, so if you're willing to live with the occasional color aberration in the bokeh, the Canon is a solid option for autofocus shooters.

The lens itself measures 4.4 by 3.2 inches (HD), weighs about 1.7 pounds, and accepts 72mm screw-in filers. It can focus as close as 3 feet, which isn't as close as the Zeiss Apo Sonnar (2.6 feet), or the Sony Carl Zeiss 135mm f/1.8 (2.5 feet) for Sony Alpha SLRs. There's a large manual focus ring, as well as a switch to toggle between manual focus and autofocus. A reversible lens hood and a soft carrying case are included.

I used Imatest to check the sharpness of the 135mm when paired with the full-frame EOS-1D X. The lens captures detail that's better than the 1,800 lines per picture height we require to call it sharp. At f/2 it manages 2,117 lines, and things get better as you close down the aperture. At f/2.8 the score increases to 2,269 lines, it's 2,489 lines at f/4, and it peaks at 2,630 lines at f/5.6. Edges are impressive as well, starting at 1,795 lines at f/2 and steadily increasing to 2,300 lines by f/5.6. Distortion is well controlled; there's only 0.5 percent, which is barely noticeable. As impressive as the results are, they don't match the Zeiss Apo Sonnar. It scored 3,357 lines at f/2, with edges that were nearly as sharp as the center (3,200 lines), and peaks at 3,887 lines at f/5.6. Those tests were done on a camera with a higher resolution image sensor, but for a better comparison we looked at the rather banal shots of our SFRPlus test chart side-by-side on a calibrated NEC MultiSync PA271W display. Magnification was set so that they were roughly equal size on the screen, and the Apo Sonnar came out ahead in terms of sharpness.

But a manual focus lens isn't for everyone. If you're an autofocus shooter with a Canon camera system, it's hard to beat the Canon EF 135mm f/2L USM. It's quite sharp and the f/2 aperture allows you to capture images with a shallow depth of field. There's no optical stabilization, but we've not seen a 135mm f/2 with that feature. Our Editors' Choice, the Carl Zeiss Apo Sonnar T* 2/135, is sharper and eliminates spherical aberrations that cause color shifts, but it's more expensive and requires you to focus it manually.

Source: http://feedproxy.google.com/~r/ziffdavis/pcmag/~3/GyNd9Dq3pjU/0,2817,2421660,00.asp

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