The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 18-250mm f3.5-6.3 II 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, 7% (32g) lighter than the Tamron AF 18-250mm f3.5-6.3 II LD's weight of 430g.
Filter Threads
Both the Tamron AF 18-250mm f3.5-6.3 II 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 18-250mm f3.5-6.3 II 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 Monochrome, Pentax KF and Pentax K-3 III.
Tamron AF 18-250mm f3.5-6.3 II LD is also available in Canon EF , Nikon F (DX) 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 18-250mm f3.5-6.3 II LD has a focal range of 18-250mm and
13.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-375mm when used on a APS-C / DX format camera.
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.