Although the maximum focal length is increased, the minimum object distance remains nearly the same, so the magnification ratio during close focusing is enhanced. Both tele converters are carefully designed and constructed to preserve the original superior image quality of the lens.
The 1.4x model uses one LD (Low Dispersion) lens element to suppress aberrations. BBAR (Broad-Band Anti-Reflection) coatings are deployed on both models to help minimize ghosting and flare.
