The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 28-300mm f3.5-6.3 XR LD and the Tamron AF 18-200mm f3.5-6.3 XR II LD for their suitability to various photography scenarios:
Size and Weight Comparison
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. Tamron AF 18-200mm f3.5-6.3 XR II LD weighs 398g, 5% (22g) lighter than the Tamron AF 28-300mm f3.5-6.3 XR LD's weight of 420g.
Below you can find the dimension and weight table of the SuperZoom Lenses in Pentax KAF Mount for size comparison purposes.
Superzoom Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
Both the Tamron AF 28-300mm f3.5-6.3 XR LD and the Tamron AF 18-200mm f3.5-6.3 XR II LD have the same Filter thread size of 62mm.
Below are links to the 62mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Tamron AF 28-300mm f3.5-6.3 XR LD and the Tamron AF 18-200mm f3.5-6.3 XR II LD 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 28-300mm f3.5-6.3 XR LD is also available in the Canon EF , Nikon F (FX) and Sony Alpha mounts.
Tamron AF 18-200mm f3.5-6.3 XR II LD is also available in Canon EF , Nikon F (DX) and Sony Alpha mounts.
Focal Range
Tamron AF 28-300mm f3.5-6.3 XR LD has a focal range of 28-300mm and
10.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 450mm.
On the other hand, the Tamron AF 18-200mm f3.5-6.3 XR II LD has a focal range of 18-200mm and 11.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-300mm when used on a APS-C / DX format camera.
