Astrophotography has two technical ceilings: lens coma at wide apertures, and star trailing from the Earth’s rotation. The Zeiss Batis 18mm f/2.8 addresses the first better than most lenses at this focal length and price point. The second is addressed by the 500 rule — the maximum exposure length in seconds before stars begin to trail, calculated as 500 divided by the full-frame equivalent focal length. At 18mm, that gives approximately 27 seconds.