There are some questions about photographic lenses.

1 and b lenses are expensive on Vario-TessarT* and 4. Vario-Tessar indicates that the lens structure is zoom sky plug structure, T* indicates T* coating of Zeiss, and 4 indicates constant aperture. Yes, the effect of lens B is better than that of lens A, which is why it is expensive.

2, 28-70 is the focal length of the lens, and there are two numbers for zoom lens, and there is only one number for fixed focus lens.

3. "3.5-5.6" of lens A is the aperture parameter, "4" of lens B is also the aperture parameter, "3.5-5.6" is the variable aperture, and "4" of lens B is the constant aperture.