There are a number of ultra wide zooms available for the Canon EF mount. Canon has two high-quality offerings: the 16-35 f/2.8L and 17-40 f/4L. The 16-35 lens is over $1,000 and out of reach for most non-professionals, but the 17-40, though still around $700, has garnered much praise and sales.
Of the major third-party lens makers, only Tamron and Sigma have competing zooms. Sigma and Tamron both make 17-35 f/2.8-4 lenses. Sigma also makes a couple of lenses for the reduced image circle of lower-end digital SLRS (those with crop factor of 1.5-1.6), including the 18-50 f/2.8 and 18-125 f/3.5-5.6.
My interest was in an ultra wide zoom for Canon Digital Rebel (300D) but with full-frame capability for future use. I was mostly interested in performance at the wide end (17-24mm). I had seen good coverage of the Tamron, not so good coverage for the Sigma, so decided to compare the Canon 17-40 f/4L and Tamron 17-35 f/2.8-4, at 17mm. I paid $470 for the Tamron, and $700 for the Canon.
All shots were taken on a tripod with manual selection of shutter and aperture which was set identically for each lens. The camera was set to JPEG, Large Fine, Sharpness -2, Contrast 0, Color 0, Tone 0.
First, here is a reduced image of the whole scene, at f/8. The Tamron image is brighter than the Canon image, and was at every aperture compared. This may affect subjective comparison of color and contrast, but I think that, exposure aside, both cameras exhibit good contrast and saturation. The tripod was not moved between lens changes, but the framing is slightly different. The Tamron is producing a wider field of view.
Tamron:
Canon:
Next is a comparison of the bottom of the books at 100% crop (i.e., pixel for pixel). Here, the Tamron images at f/2.8 and f/4 are shown, then Canon at f/4. Clearly, the Tamron is not as good at f/2.8, but is certainly very usable. At f/4, the Tamron exhibits better sharpness and micro-contrast across the frame.
Click image to open the full-sized version in a separate window.
At f/8, the lenses are very close, but the Tamron still holds the edge, especially at the left hand side.
Click image to open the full-sized version in a separate window.
Overall, the Tamron beats the Canon indoors, by my estimation. It is sharper, has a bit more contrast, and a whole extra stop of light. The Canon is no slouch though, and both lenses are very good. Distortion is about the same in each case (it required the same amount of debarellizing in Photoshop to make the curves straight).
Copyright © Martin Scott, October 2004. All Rights Reserved.
