Zeiss 135mm f/2.0 APO-Sonnar T ZE Lens, Canon Mount Because this lens is an apochromat, chromatic aberrations (axial chromatic aberrations) are corrected with elements of special glass with anomalous partial dispersion. The chromatic aberrations are therefore significantly below the defined limits Great low-light shots start with a great lens for your DSLR camera. A high-speed lens captures as much light as possible. A lens with a wide maximum aperture offers the best results in difficult lighting conditions The lens design ensures consistent imaging performance throughout the entire focusing range as well as sharpness to the periphery of the image. The asphere's more complex surface profile can reduce or eliminate spherical aberration and also reduce other optical aberrations compared to a simple lens Rich, vibrant colors are vital to creating a lasting impression. Stray light in the lens, however, would lead to a brightening of the image, which is particularly visible in shadow areas. Image contrast is lowered; the image appears dull and bleached Photographers want to guide the observer through the image. Minimal depth of focus is often used as a design element. This keeps the background intentionally blurred to keep the attention of the observer on the main subject