The Color Skopar is by far the better lens. You'll see that when making prints. The shots with the Elmar seem to fall apart, the details are sharp, but there is no wholeness, no completeness of the image. The Skopar has seven elements, the Elmar four. The Skopar has a very little bit of distortion, but is at least as sharp as the Elmar, has a better build quality and is much handier in use. The black Color Skopar 50mm f/2.5 - black paint - is the most beautiful lens made by Cosina.
The S Skopar in Nikon S mount - the same optics as the Color Skopar - is by the way the best 50mm available for the Nikon rangefinders. It is all the time on my black paint S2.
Color Skopar 50mm f/2.5. Print on Adox MCC 110.