What is the effect on the interference fringes in Young's double slit experiment if the source slit is moved closer to the double slit plane?

Let x be the width of the source slit and X be the distance between the source slit and the plane of the two slits. For interference fringes to be distinctly visible, the condition $\frac{x}{X}<\frac{\lambda }{d}$ should be satisfied. If x is too large (i.e. the source slit is too wide) or if X is too small (X is the distance between the source slit and the two slits) the requirement$\frac{x}{X}<\frac{\lambda }{d}$ may be violated and fringes will no longer be distinct. The reason is that the interference patterns due to various parts of the source slit overlap. Consequently, the minima will not be totally dark and fringe pattern becomes indistinct. However, as long as the fringe pattern remains visible, a change in x or X has no effect on the fringe width $\beta$.