It is well known that telescopes magnify the image. However, it is not often mentioned that they also reduce the depth of field. Inverted Galilean telescopes obviously minify the object apparent size, but the depth of field is also increased. It has been observed that myopic persons wearing correcting noncontact eye glasses develop noticeable presbyopic effects at a later age than emmetropic persons. This effect may be explained by considering that the negative correcting lens and the positive myopic dioptric power of the eye together form an inverted Galilean telescopic system.