Abbreviation: Di-II = "Digitally Integrated (APS-C)" (Tamron)
The abbreviations means "Digitally Integrated (APS-C)"
Explanation from Tamron
Digitally Integrated Lenses Optimized for APS-C Format Digital SLR Cameras
Tamron Di-II lenses are engineered expressly for digital SLR cameras with image sensors commonly referred to as APS-C, measuring approximately 24mm x 16mm. Rendering an ideal image circle for APS-C sensors, Di-II lenses also include properties to optimize digital imaging performance.
See examples of effected products
|Tamron SP AF 17-50mm f/2,8 XR Di-II LD Asph IF|
|Tamron SP 11-18mm f/4,5-5,6 Di-II|
|Tamron AF 18-250mm f/3,5-6,3 XR Di II|