Image: Sigma Sigma has announced its newest optic, the 28-45mm F1.8 DG DN Art lens for E-mount and L-mount cameras. The lens covers a wide-to-standard focal range, and Sigma claims it's the first constant aperture F1.8 zoom lens for full-frame mirrorless cameras. Sigma is setting high expectations for this lens, claiming that it achieves image quality comparable to prime lenses and that it exceeds the performance of its own 24mm F1.4 DG DN and 50mm F1.4 DG DN Art lenses. To do this, the 28-45mm ...