The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax DA 18-50mm F4.5-5.6 DC WR RE and the Tamron AF 28-75mm f2.8 XR LD for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Tamron AF 28-75mm f2.8 XR LD is the longer of the two lenses at 92mm. The Pentax DA 18-50mm F4.5-5.6 DC WR RE with a length of 71mm, is 21mm shorter. Besides being longer, the Tamron AF 28-75mm f2.8 XR LD also has a larger diameter of 73mm compared to the Pentax DA 18-50mm F4.5-5.6 DC WR RE's 41mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Pentax DA 18-50mm F4.5-5.6 DC WR RE weighs 158g, which means it is 352g (69%) lighter than the Tamron AF 28-75mm f2.8 XR LD which has a weight of 510g.
Filter Threads
The Pentax DA 18-50mm F4.5-5.6 DC WR RE has a filter size of 58mm whereas the Tamron AF 28-75mm f2.8 XR LD has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the Pentax DA 18-50mm F4.5-5.6 DC WR RE:
And these are the 67mm filters that we recommend for the Tamron AF 28-75mm f2.8 XR LD:
Lens Mounts
The Pentax DA 18-50mm F4.5-5.6 DC WR RE has the Pentax KAF3 lens mount whereas the Tamron AF 28-75mm f2.8 XR LD has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Tamron AF 28-75mm f2.8 XR LD is also available in Canon EF , Nikon F (FX) and Sony Alpha mounts.
Focal Range
Pentax DA 18-50mm F4.5-5.6 DC WR RE has a focal range of 18-50mm and
2.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-75mm when used on a APS-C / DX format camera.
On the other hand, the Tamron AF 28-75mm f2.8 XR LD has a focal range of 28-75mm and 2.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 42 - 112.5mm.
