The FL or Breech Lock Canon lenses were decent in their day. Sharpness is excellent but they are prone to aberations and flare. At f3.5 the FL 35mm 3.5 is sharp, but there is noticeable bokeh fringing. Due to the basic coating on this FL lens, flare is an issue in shots with strong back or side lighting. Color rendition is good if lighting is good. Contrast is excellent from f3.5 up. Focusing on the Eos M3 is dificult. Images from this lens can have a nice depth and texture.