The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 70-300mm f4-5.6 LD and the Pentax 50-200mm F4-5.6 ED WR 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 70-300mm f4-5.6 LD is the longer of the two lenses at 117mm. The Pentax 50-200mm F4-5.6 ED WR with a length of 80mm, is 37mm shorter. Besides being longer, the Tamron AF 70-300mm f4-5.6 LD also has a larger diameter of 77mm compared to the Pentax 50-200mm F4-5.6 ED WR's 69mm 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 50-200mm F4-5.6 ED WR weighs 285g, 34% (150g) lighter than the Tamron AF 70-300mm f4-5.6 LD's weight of 435g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Pentax KAF Mount for size comparison purposes.
Telephoto Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
The Tamron AF 70-300mm f4-5.6 LD has a filter size of 62mm whereas the Pentax 50-200mm F4-5.6 ED WR has a 49mm 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 Tamron AF 70-300mm f4-5.6 LD:
And these are the 49mm filters that we recommend for the Pentax 50-200mm F4-5.6 ED WR:
Lens Mounts
Both the Tamron AF 70-300mm f4-5.6 LD and the Pentax 50-200mm F4-5.6 ED WR has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Tamron AF 70-300mm f4-5.6 LD is also available in the Canon EF , Nikon F (FX) and Sony Alpha mounts.
Focal Range
Tamron AF 70-300mm f4-5.6 LD has a focal range of 70-300mm and
4.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
105 - 450mm.
On the other hand, the Pentax 50-200mm F4-5.6 ED WR has a focal range of 50-200mm and 4.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 75-300mm when used on a APS-C / DX format camera.
