The PPI Model 110 Laboratory Photometer has 11 input ranges from 10 microA to 100 pA, with 1 pA resolution. Dark current cancellation is switchable to 1 microA, 100 nA, 10 nA, 1 nA, 100 pA, and OPEN. The Sensitivity control allows 3X expansion on all but the two least sensitive ranges, to set any light level to full scale. Accuracy is 1% on the meter, and 0.2% on the analog output. The regulated high voltage is variable from -50 to -2000 volts.