Vivitar 28-85mm f3.5-4.5

     Kobori manufactured this lens for Vivitar.   They, unlike many others, are still making lenses today.    Kobori has made lenses for Minolta, Nikon and many other name brands.   So, is this lens any good? 
     I am testing it on my Eos M3.  It is front heavy.   It also has the shortest focus throw I have ever seen.   but due to excellent dampening, it's not hard to focus. 
     Optically, it is no Kiron, but it can produce nice images.   First, avoid f3.5.  It is just too soft wide open.   Stop down to f5.6 and it tightens up nicely.

     Quality is consistent from 28mm thru 85mm.   Distortion is well controlled.   Corner sharpness is decent for a zoom lens but it does not rival primes.   
     Colors render on the cool side.    Fringing can be seen at 100% crop in high contrast lighting but it is minor.   
     Bokeh is a negative with this lens.   It's uneven hexagonal iris creates a busy and distracting bokeh.

     Macro is available at 85mm.   Macro performance appears to be very good.