The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-50mm f2.8 XR II LD and the Sony DT 18-55mm F3.5-5.6 SAM II for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Tamron 17-50mm f2.8 XR II LD is the longer of the two lenses at 82mm. The Sony DT 18-55mm F3.5-5.6 SAM II with a length of 69mm is 13mm shorter. Besides being longer, the Tamron 17-50mm f2.8 XR II LD also has a larger diameter of 74mm compared to Sony DT 18-55mm F3.5-5.6 SAM II's 72mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Sony DT 18-55mm F3.5-5.6 SAM II weighs 222g, 48% (208g) lighter than the Tamron 17-50mm f2.8 XR II LD's weight of 430g.
Below you can find the dimension and weight table of the 'Standard Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Standard Zoom Lenses in Sony Alpha Mount for Size Comparison
Lens Mounts
Both Tamron 17-50mm f2.8 XR II LD and Sony DT 18-55mm F3.5-5.6 SAM II has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.
Tamron 17-50mm f2.8 XR II LD is also available in Canon EF , Nikon F (DX) and Pentax KAF mounts.
Focal Range
Tamron 17-50mm f2.8 XR II LD has a focal range of 17-50mm and 2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-75mm when used on a APS-C / DX format camera. Sony DT 18-55mm F3.5-5.6 SAM II has a focal range of 18-55mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-82.5mm when used on a APS-C / DX format camera.