The Carl Zeiss Planar T* 1,4/50 ($725 list)SEE IT is a fast standard-angle lens for Canon and Nikon cameras. It's very compact at just 2.8 by 2.8 (HD) inches and weighs only 13.4 ounces. Its barrel is all metal, and the large manual focus ring—autofocus isn't supported—has small ridges for a better grip. It can focus on objects as close as 17.7 inches, which, when combined with the f/1.4 maximum aperture, makes for photos with a very shallow depth of field and smooth, blurred backgrounds.

I used Imatest to check the sharpness of the lens when paired with the Nikon D600 and found the results to be disappointing at f/1.4 and f/2. We consider a sharp image to be one that scores 1,800 lines per picture height using a center-weighted algorithm—this takes edges into account, but gives more credence to the center of an image. The Planar only manages 1,085 lines using this methodology at f/1.4. The image looks like it has a glow, and the black-on-white squares on our test chart display blurry edges, rather than a distinct contrast as you'd expect to see.

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At f/2 it sharpens up a bit, especially in the center, but its score is only 1,541 due to edges that are still soft. At f/2.8 it's almost as if you're shooting with a different lens—it's sharp throughout most of the frame and scores 2,531 lines on our test, although there is some still softness in the extreme corners. Stopping down to f/8 gives you corner-to-corner sharpness and a score of 2,881 lines. The lens does exhibit about 1.7 percent barrel distortion, which gives a slight curve to straight lines.

Both Canon and Nikon make 50mm lenses that are sharper. The Nikon AF-S Nikkor 50mm f/1.8G £199 at Amazon UK is a budget lens that sells for only $220, but still manages to notch 1,795 lines at f/1.8 and 2,276 lines at f/2.8. Canon's top-end 50mm, the EF 50mm f/1.2L USMSEE IT scores 1,573 lines at f/1.2, improving to 1,744 lines at f/1.4 and 2,319 lines at f/2.8—but it's priced at $1,620.

The Carl Zeiss Planar T* 1,4/50 is an anomaly in the Zeiss SLR lens lineup. It's the only lens that's available for less than $1,000, but of the ones that we've tested, it's the first to deliver anything but admirable sharpness at its maximum aperture. At the Photokina trade show last month, Zeiss announced that it's working on a new 55mm f/1.4 SLR lens using a Distagon design, traditionally reserved for wide-angle optics, which is poised to rival medium format lenses in terms of resolution. Zeiss used this type of lens design in the Distagon T* 1,4/35SEE IT, a lens that is impressively sharp at every aperture. In the meantime, if you are after a fast 50mm lens for your Canon or Nikon camera, this Zeiss optic is an option, just be prepared for soft edges at f/1.4. At that aperture it produces images with a soft, dreamy look and smooth bokeh—and if that's what you're after, this lens delivers. But if you just want a basic, sharp photo, an inexpensive autofocus Canon or Nikon 50mm lens will suffice.

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