Vivitar 75-260mm f4.5

     Made by Tokina.  This lens is a bear.  Thankfully, it has a tripod mount.   It is impossible to hand hold.   
     I've begun testing it with my T2i but I think it will produce better results on a mirrorless body.   Critical focus is difficult to achieve on a D-slr.  The lens is made very well.   Zoom and focus rings are very smooth and well dampened,   F-stops click nicely.

     It is reasonably sharp @ f4.5 and sharp at f8 thru the entire zoom range.   
     Contrast is noticeably low and color rendition is a bit flat.    
     Purple finging can be seen at 100% crop but well controlled.  

     Bokeh is less distracting than many tele-zooms but it doesn't compare to the smoothness of a prime lens.

     Flare hasn't been tested.

     This lens can be found for a very reasonable price.   If you don't mind lugging it around and doing a little extra post-processing of your images it can produce good results.