Yashica DSB 28mm f2.8

     Yashica lenses in the Yashica/Contax era were made by Tomioka.   While the ML line is generally superior to the DSB line, the DSB's can be a good performers.   This lens is all metal and glass except for the rubber focus ring.   It focuses down to 11 inches and has a typical focus throw of 1/2 turn.   The aperture ring clicks at full stops from f2.8 to f16.   Focus dampening is much like a Yashinon lens;  Smooth with medium resistance.

     It handles well on the full frame 6D.   Focusing is always a chore with a manual focus 28mm lens on a D-slr, though.

     At f2.8 it is reasonably sharp.   Corners fall off steeply and there is a typical vignetting.   At f4 it become much better across the frame.  Corners tighten up and vignetting fades.   

     Edge sharpness is excellent at all apertures.   

     There is a significant amount of barrel distortion which strongest at f2.8.  

     Color rendition is neutral. 

     Contrast is quite good at all settings.  

     Side lighting is handled quite well.  I didn't see any loss of contrast or flaring in strong side light.

     Bokeh is not silky smooth but not overly distracting either.    Bokeh fringing tests show a slight color shift but it is gone by f5.6 and contrast is excellent.

     This is a very good student lens.   Shoot landscapes at f8 on film or full frame and use it as a standard lens on a sub frame D-slr.   It should also produce excellent close ups when used with extension tubes or a bellows on a sub frame body.