[longrange1947]

Peregrino - Actually for range work you can use 3.5 moa for mils and 1 moa equals 1 inch every 100 yards or 100 meters. The error is not enough to matter at normal ranges. Use 25.4 as a constant to change inches into meters, or 27.7 if you like to work in yards. If your target is in meters then use 1000. The formula words by chagning the sizr of the target into millimeters and dividing by the measured mils. Hence 25.4, number of mm in an inch and 1000 number of mm in a meter. The 27.7 is a formula number to trick the formula into giving yards as an answer. Use the calculator for figuring practice targets at shorter ranges. Make the targets anysize you wish and then measure them to see what they would be if they were a 1 meter 'E' type at that a simulated range. An example is that the target is used at 50 meters. Make the target out to be 10 cm and you have a target that is 2 mils tall or 500 similated meters away. .10 x 1000 / 2 = 500.

Desert Fox - What you are talking about is matching the exit pupil of the scope with your pupil size. Divide the Objective lens in mm by the power fo hte scope and you have the exit pupil. As an example 50mm divided by 8x equals 6.25mm, this would be slightly smaller then your pupil at night so you would have a hard time locating the true center axis of your lens. Go too large and you are wasting light on other than your pupil.