Sigma Announces World’s First F1.8 Constant Aperture Zoom | PDNPulse In a very exciting bit of news for photographers who live and breathe in the low-light world, Sigma today announced a 18-35mm F1.8 DC HSM lens. A constant f/1.8 zoom lens is one and a third stops faster than the f/2.8 lenses that we normally consider … Continue reading Sigma Announces World’s First F1.8 Constant Aperture Zoom