A \(100 \mathrm{~mm}\) focal length circular lens with a \(F\)-number \(=4\) is used to image a 100 line \(/ \mathrm{mm}\) cosine grating with a contrast of 0.5 in a one-to-one imaging system illuminated with incoherent light of approximately \(500 \mathrm{~nm}\). Calculate the contrast of the image. If this same lens is used to image this grating with a magnification of

(a) 0.25 ,

(b) 0.5 ,

(c) 2 ,

(d) 4 . What is the contrast of the image in each case?