A student adjusts a simple microscope so that the final image is at infinity instead of at the least distance of distinct vision. If the focal length of the lens remains unchanged, the magnifying power becomes

For a simple microscope, two standard cases are used. If the final image is at the least distance of distinct vision, $m=1+D/f$. If the final image is at infinity, $m=D/f$. Since $D/f$ is smaller than $1+D/f$, shifting the final image to infinity reduces the magnifying power by 1.