In a search of an affordable midrange zoom for a photojournalism kit, to go along with a Nikon 12-24mm and 80-200mm, the 24-85 f/3.5-4.5, the 24-85 f/2.9-4, and the Tamron 17-50 were tested for sharpness at an f/5 aperture and 50-85mm focal length. This does not pretend to test the extremes, but rather a representive way such a midrange zoom would often be used. All lenses should be able to do well in this area.

The Nikon 18-135 was used as a reference standard, since both objective testing and reviewer consensus is that it is the sharpest of the DX zooms, equallying the newer 16-85vr in this respect.

The pics below are of 2000 x 1335, large enough to examine closely, with the 18-135 first, and then the three contenders in terms of increasing sharpness in this man's opinion (18-135 left, followed by the 24-85 f/3.5-4.5, 24-85 f/2.8-4, and Tamron 17-50, low-to-high, in that order.

To reach this opinion, I've concentrated on the middle right hand window area, on the subtle details of the masonery, on the area of peeling paint on the bottom of the frame, and on the guitar (upper window) and sewing machine or microwave(?)and assorted spools and plants (middle window). The interior perspective changes for the Tamron shot since I had to get closer (and thus lower) because of the 50mm max reach of this lense.

All photos were shot as NEFs, processed through DxO2's default processing into high density TIFFs, were cropped and had dynamic range touched up and equalized (using histogram), and were then converted into JPEGs. Conversion auto-sharpening was applied equally to all shots both during the DxO conversion to TIFF and again during the PhotoMechanic conversion to JPEGs, but otherwise was not touched. Focus was on the right side of he tree.