The SMC Tak 135mm f3.5 is a great little telephoto. Solid, very well dampened. Tack sharp from f3.5 in the center. Almost as sharp in the corners. Mild vignetting at f3.5, gone by f5.6. No noticeable diffraction at f16. Contrast is slightly lower than the 200 f4 SMC Takumar. That makes sense as most 135's are designed for portraits. Bokeh is smooth with a smooth transition. Some minor color shift in high contrast transition areas.