PROCEDURE III: Light gathering power and field of view Use Equation 2 Download Equation 2 to calculate the light gathering power of all four sets of binoculars, compared to the human eye, which has a diameter of approximately 5 mm. Record your results in Table C. Use the appropriate units. n Using the magnitude scale information in Table A, estimate the magnitude gain that each set of binoculars would provide. Record this magnitude gain in Table C. For help on this and the next step, refer to the boxed sample calculation, below. Since the naked eye can see down to magnitude 6 in absolutely ideal conditions, calculate the limiting magnitude for all four binoculars. Record this in Table C. Limiting Magnitude sample Calculation Limiting magnitude sample calculation A 40 mm diameter pair of binoculars, compared to the human eye (5 mm diameter), would have a relative LGP of... LGP = (40 mm/5 mm)2 = 64 x Table A shows that a difference in 64x brightness corresponds to approximately 4.5 mag. This means the limiting magnitude would be approximately 6 4.5 = 10.5 Table A 1.0 mag = 2.5 x 2.0 mag = 6.3 x 3.0 mag =16