Angular width of central maximum of a diffraction pattern of a single slit does not depend upon
 

Angular width $\mathrm{\beta }=\left(\frac{\mathrm{\lambda }}{d}\right)=\left(\frac{\mathrm{c}}{\nu d}\right)$
where, d= width of the slit, c = velocity of light and v= frequency. Hence angular width does not depend upon distance between slit and source.