Yendor. By your use of "bokeh" I think you mean "background blur", ie, the separation
of the subject from the BG using image blur. Bokeh means the type of blur the lens can
produce (usu at given f-stops). As an illustration, think of the OOF donut-shapes a mirror
lens produces as its bokeh, compared to the general softness of non-mirror lenses.
Here is a basic definition of the term: https://www.google.com.au/search?q=b...Fonp8wfowpiQDA
while this one is rather confused and popularised: http://www.nikonusa.com/en/learn-and...beginners.html