The Science - Our eyes are very unique: a young person's pupil dilates between 2 and 7 millimeters, yet, the eye posses the ability to view images several thousands meters in diameter. Our wide field of view provides convincing evidence that we view converging image rays and not parallel rays. Converging image rays obeys the inverse square law of electromagnetic radiation. Converging rays describe rays that convert towards a point. Therefore, image carried by these rays reduce their cross sectional area with distance travel. Images collected by the largest telescope aperture, actually enters the few millimeters of our eyes. Small sight angle (true field) at seconds of a degree, so small the brain finds it difficult to isolate the details they contain for recognition, when they are factored into our full field of view. These small-angles of information get compressed within our large field of view, and appear to be just a small spot or become invisible.

Nevertheless, magnification provides the means by which small sight angles are converted into larger ones. A refractor telescope with an aperture of 30 millimeters and 120 millimeters focal length (focal ratio f/4), providing a magnifying power of 5x times and will have an exit pupil of 5 millimeters. This is a very bright telescope, tapping close the maximum of 7 millimeters opening of the pupil. If a second telescope was constructed, having identical aperture size of 30 millimeters, but have a focal length of 1200 millimeters (f/40). The magnifying power will be 50x times. Instead of a 5 millimeters exit pupil, such telescope will now have an exit pupil of only 0.5 millimeter. From the same formula, to obtain a 50x times magnifying power and an exit pupil of 5 millimeters, the aperture needed is 300 millimeters.

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