Tamron Zoom Lens AF 70-300mm 1:4-5.6 Test Results

Tamron Zoom Lens AF 70-300mm 1:4-5.6

Aperture Range [f]	4.0-5.6 to 22-27	Closest Focus	1.42m / 56 in.
Dimensions	126mm x 74mm / 4.9 in. x 2,9 in.	Magnification Ratio	0.33x / 1:3
Weight	510g / 18 oz	Filter Size	58mm

This is an old lens, no longer on a market. I present its analysis just to compare performance of about 10-fold less expensive lens than Canon makes. For such a long focal length zoom lens, its size and weight are exceptionally attractive as well. The tests were done at manual focus for the 70mm and on autofocus for the longer f.l. settings.

I've tested this Tamron lens on 3 focal lenghts, 70, 180, and 300 mm. Analysis at the 70 mm at various f stops is given here. It is the sharpest at f/8 and f/11. Important note: autofocus at 70mm did not work properly, and gave very blurred pictures, so I had to use manual focus for this focal length. Dependence of the image quality in various parts of the full 24x36mm frame is shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart.

At f/4 the lens sharpness is moderate, but the worst problem is a low contrast. These are improved considerably at f/8 and f/11. At optimum apertures the sharpness is very good and even it surpasses Canon's 100-400mm "L" zoom. The circles size and shape remain constant throughout the entire frame. Chromatic aberration is remarkably low.

Analysis at the 180 mm setting at various f stops is given here. It is the sharpest at f/8. Dependence of the image quality in various parts of the full 24x36mm frame is shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart.

At the full aperture the sharpness is somewhat lower than at f/8 or f/11, and the contrast is low. At the optimum aperture the lens performance is much better, as expected (resolution of "37" is the max. theoretical number in this test) but beyond the 12th mm is not good either, with various strange distortions. There is a 2.2% increase of the circle diameter at the sides of the frame compared to the circle size at the center (10 to 4 o'clock axis). At the sides the circles look elongated slightly, with a 6.3% difference in extreme diameters, and this is a significant distortion. The chromatic aberration easily noticeable. Working with a 1.6x smaller than full frame DSLR at f/8 or higher is an acceptable choice.

Analysis at the 300 mm at various f stops is given here. It has best performance at f/11. Dependence of the image quality in various parts of the full 24x36mm frame is shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart.

Again, at the wide open aperture the contrast is below par, with a reasonable sharpness except at the very corners is a variable directional resolution. Sharpness at f/11 is very good in the center with a 12mm radius. There is a 3.1% increase of the circle diameter at the sides of the frame compared to the circle size at the center (10 to 4 o'clock axis). At the sides the circles look elongated slightly, with a 4.6% difference in extreme diameters, a large distortion, especially for this focal lenghts lenses. There is strong chromatic aberration.

Besides some optimum settings this lens cannot be used reliably. Lack of correct autofocus at 70mm and lack of contrast are a big problem. At higher focal lenghts AF works well and contrast is better, but the distortions are significant. If it does not bother you much working with this lens only at its "sweet settings", it is not a bad choice considering its bargain price, low weight and small size. I don't recommend it using for any full frame cameras.

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