Canon Zoom Lens EF 28-300 mm f/3.5-5.6 L IS USM
|Aperture Range [f]||3.5-5.6 to 32-38||Closest Focus||0.7m / 2.3 ft.|
|Dimensions||184mm x 92mm / 7.2 in. x 3.6 in.||Magnification Ratio||0.3x / 1:3.3|
|Weight||1.67kg / 3.7 lb||Filter Size||77mm|
This is a heavy, well built high power (10.7x) zoom lens that fits on full frame, 24x36mm, cameras. It focuses well and fast.
Click on the "Various f-stops" thumbnail below, to see the charts made at different f stops and focal lengths. Only one circle chart is displayed: at the 12th mm from the center image (The center chart was always very sharp, so that there were no significant differences). The sharpness was best mostly at f/11, but at wide angle settings the f/8 gave also good results.
I've tested this Tamron lens on 8 focal lenghts, 28, 35, 50, 70, 100, 135, 200, and 300 mm. Three groups of charts are available, those made at the wide-open lens (click on the "Tests at low fs" thumbnail), made at f/8 and at f/11. To see the charts in full magnification please click on the thumbnails below (note: large images, 1720x1850, 0.5M each). Dependence of the image quality in various parts of the full 24x36mm frame is shown, with the average resolution in hundreds of line widths per picture height (LW/PH), given below each chart.
Tests at low fs
Tests at f/8.0
Tests at f/11.0
At wide open apertures the image quality varies significantly, depending on a distance from the image center, with low to moderate contrast across all focal length. There are quite bizzare distortions at the image sides, see the figure below (charts were enlarged 2x for easier viewing). There are some bands of fuzziness, well seen on 15 and 18mm charts of 50 and 70mm focal lengths. In extreme cases it leads to doubling of small fragments of the images, see a crop of the chart in the center, that leads to doubling of the chart lines - see the arrows pointing to the line split points.
At higher f-stops these problems disappear, and the images look a lot cleaner. At f/11 the lens performance is very good for DSLR's with APS-C sensors. Maximum resolution of 37 LW/PH is observed at many charts, especially at low focal lengths at or near the image center. On the sides the image has still respectable sharpness, however, many of the charts show variable sharpness depending on the lines direction. The poorest performance is observed at focal length of 200mm with fuzzy lines still visible even at f/11 in the corner chart.
Depending on the focal length the distortions are variable. In some cases circle charts at the frame corners are smaller than in the center (5.6% at 28mm with 4.4% difference in extreme axes of the ellipse), and in most larger. Maximum distortions were spotted at 50mm: circle size increased by 5.6% and the difference in extreme radia of the ellipse was 5.7%. The smallest resolutions were observed at high focal lengths (still very good, reaching 3500 lines mark, and with less distortions. Chromatic aberration is generally low, but becoming a concern only at the extreme focal lengths.
Compared to the Tamron Zoom Lens AF 28-300 mm, its performance at f/8 and f/11 is better at the high and low ends of the focal lengths, and similar at medium ranges. However, the quality at the corners seem generally better in the Tamron lens. At lower apertures the quality gap increases in the favor of the Canon lens. Interestingly looks the comparison with the two small Canon lenses, 24-58mm and 75-300mm that cumulatively cover even wider focal length ranges. Those two lenses give better picture quality, cumulatively weigh twice less and cost 4x less than this single one. Two groups of users may be fully satisfied with this lens. The first is the one that have problems with lens changing procedures, and another one is the group that carry the camera mostly to impress his colleagues how serious or 'professional' they are as the lens is really well built and looks impressive, especially when fully extended. I would not recommend it for travel because of the big size and heavy weight, although it is generally recommended for this purpose.
Acknowledgement: This lens was made available to PPP thanks to the courtesy of LensRentals.com.
© 2009 PikesPeakPhoto. All rights reserved.