The Leica Tri-Elmar-M 16-18-21mm f/4 Aspherical Lens gives incredible versatility & optical brilliance to the Leica shooter who doesn't need the higher speed of the single focal length lenses. The Tri-Elmar is not a zoom, but a three focal length lens offering 16mm, 18mm and 21mm choices with a simple twist. Due to the minimal distortion and barely perceptible field curvature, it can be recommended for highly demanding architecture photography even at the 16mm setting. Used on the digital M8, it produces the image effect of a 21 - 28 mm lens, still enabling extreme wide-angle views.
Included in this kit is the Universal Wide-Angle Viewfinder. The viewfinder enables precise cropping of the subject with the Tri-Elmar-M 16-18-21mm f/4 on the M7 and MP as well as the digital M8. For the M8, the focal length extension factor of 1.33x has to be considered, so in this case the bright-line frames for 21, 24 or 28 mm are selected.
This lens has been updated with the "6-bit" coding, which allows the digital M camera to read this information optically and to identify which lens is being used. The camera can then (optionally) apply a "final stage" software based vignetting correction (for RAW images the lens used is simply recorded, no change is made).