For a lens with twice the speed this is a remarkable feat. Now the circle has been squared. The lens operates very smoothly, and the aperture ring clicks with just the right amount of resistance and fluidity. At full aperture this lens exhibits a high contrast with crisp definition of exceedingly fine detail over most of the image field, softening in the field from image height of 9mm. A faint trace of astigmatism and field curvature can be detected.
Corners however lag a bit and stay soft with a limited definition of coarse detail.
Stopped down to 4, contrast becomes very high and the optimum is reached with a very even performance over the whole image area, excepting the extreme corners. At 5.6 we se a small drop in microcontrast of the fine textures and from 8, the overall contrast drops a bit. We have to put this in perspective, of course as we relate it to the optimum aperture. Close up performance at 0.7 meters and full aperture shows excellent performance with high contrast rendition of very fine detail. At least with slide film and Black and White.