acuity of 0.1 is sufficient for a person to be able to orientate themselves outdoors. However, a visual acuity of 0.8 is required for reading travel timetables. Other minimum values include: 0.4 for watching [...] watching television, 0.5 for reading the newspaper and 0.7 for reading a telephone directory. Is the ability of the eye to read solely dependent on visual acuity? No. In order to be able to read we require [...] of the field of view. With only two standard batteries, the necessary voltage is stepped up to the 3.6 volts required. The step-up converter used here guarantees bright, even illumination over a long period
