Vivitar Series 1 90mm f/2.5 Macro OM-1 with mirror lockup Vignetting = A- Distortion = none Aperture Center Corner f/2.5 B- C f/4 B B+ f/5.6 B+ A- f/8 A- A- f/11 B+ B f/16 B B f/22 B B Notes: High contrast image. Book traversal links for Vivitar Series 1 90mm f/2.5 Macro ‹ Vivitar Series 1 90-180mm f/4.5 Flat Field Zoom (multi-coated) Up Pentax Lenses ›