Tamron SP 70-200mm f/2.8 Di VC USD G2 Lens for F - Manual (Page 7)

7
Optical construction
The optical design of the new A025
consists of 23 elements in 17 groups.
1 XLD (eXtra Low Dispersion) and 5 LD
(Low Dispersion) lens elements are used.
The optimum deployment of both of these
elements completely eliminates
chromatic aberrations, which tend to
become particularly prominent in
high-speed telephoto zoom lenses.