The Leica Tri-Elmar-M 16-18-21mm f/4 ASPH (often abbreviated as WATE—Wide-Angle Tri-Elmar) is a unique ultra-wide-angle lens for the Leica M-system. It is distinct for offering three separate focal lengths in a single housing without being a traditional zoom lens.
Key Technical Specifications
Focal Lengths: Three discrete settings at 16mm, 18mm, and 21mm.
Aperture: Constant maximum aperture of f/4 across all settings.
Angle of View: Up to 107° at the 16mm setting.
Optical Design: Includes two aspherical elements to minimize distortion and field curvature, making it ideal for architectural and landscape photography.
Focusing: Internal focusing with a floating element principle to maintain high image quality in the close-focus range.
Minimum Focus Distance: 0.33m (approx. 1.1 feet).
Design and Handling
Discrete Switching: The lens features a focal selection dial with distinct click-stops at 16, 18, and 21mm.
Viewfinder Use: Because Leica M-system rangefinders do not have built-in framelines for these wide focal lengths, the lens is typically used with an external wide-angle viewfinder or a digital EVF.
6-Bit Coding: Standard on this lens, allowing digital M cameras to recognize the focal length setting and apply relevant vignetting corrections.
Size: Compact and lightweight (approx. 335g) despite its versatile focal range.
Application
Architecture & Interiors: Valued for its minimal distortion even at 16mm, allowing for straight lines in tight spaces.
Landscapes: Offers sweeping perspectives with deep depth of field, particularly useful for hyperfocal photography.
Compatibility: Originally introduced to provide wide-angle options for the crop-sensor Leica M8 (where it acts like a 21-28mm lens), it remains a powerful ultra-wide tool for full-frame digital and film M-bodies.