The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 18-400mm F3.5-6.3 VC and the Tamron AF 18-200mm f3.5-6.3 XR II LD for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Tamron 18-400mm F3.5-6.3 VC is the longer of the two lenses at 124mm. The Tamron AF 18-200mm f3.5-6.3 XR II LD with a length of 84mm is 40mm shorter. Besides being longer, the Tamron 18-400mm F3.5-6.3 VC also has a larger diameter of 79mm compared to Tamron AF 18-200mm f3.5-6.3 XR II LD's 74mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Tamron AF 18-200mm f3.5-6.3 XR II LD weighs 398g, 43% (312g) lighter than the Tamron 18-400mm F3.5-6.3 VC's weight of 710g.
Below you can find the dimension and weight table of the 'SuperZoom Lenses in Nikon F (DX) Mount for size comparison purposes.
SuperZoom Lenses in Nikon F (DX) Mount for Size Comparison
Lens Mounts
Both Tamron 18-400mm F3.5-6.3 VC and Tamron AF 18-200mm f3.5-6.3 XR II LD has the same Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (DX) lenses are Nikon D3500, Nikon D7500 and Nikon D5600.
Tamron 18-400mm F3.5-6.3 VC is also available in Canon EF-S mount.
Tamron AF 18-200mm f3.5-6.3 XR II LD is also available in Canon EF , Sony Alpha and Pentax KAF mounts.
Focal Range
Tamron 18-400mm F3.5-6.3 VC has a focal range of 18-400mm and 22.2X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-600mm when used on a APS-C / DX format camera. 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.