Designed by Dr. Ludwig Bertele, the Biogon lens formula continues to garner demand from photographic fans around the world. Using the latest in optical technology, the Biogon T* 21mm has an ultra-wide angle of view of 90 degrees with low distortion. Even at maximum aperture contrast remains high. Gradation of tone, color saturation and reproduction standards are all exemplary. The Biogon T* 21mm f/2.8 lens uses a supplied optical viewfinder with a cross-hair reticle to provide an accurate view.