The type of photography that you are planning to use is an important decision factor. Here we have evaluated the PENTAX28-105mm F3.5-5.6 WR 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 PENTAX28-105mm F3.5-5.6 WR with a length of 87mm, is 5mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 73mm.
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. PENTAX28-105mm F3.5-5.6 WR weighs 440g, which means it is 70g (13%) lighter than the Tamron AF 28-75mm f2.8 XR LD which has a weight of 510g.
Filter Threads
The PENTAX28-105mm F3.5-5.6 WR has a filter size of 62mm 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 62mm filters that we recommend you to consider for the PENTAX28-105mm F3.5-5.6 WR:
And these are the 67mm filters that we recommend for the Tamron AF 28-75mm f2.8 XR LD:
Lens Mounts
The PENTAX28-105mm F3.5-5.6 WR 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 Monochrome, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount and Pentax K-3 III Monochrome, 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
PENTAX28-105mm F3.5-5.6 WR has a focal range of 28-105mm and
3.8X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 157.5mm.
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.