Less than 1 lb. May be bypassed for final dark-adapted threshold. Timer resolution is 0.1 minutes. Will measure time to several hours.
Stimulus is second flash.
Intensity is adjustable over a 3 log unit range in 0.1 log unit steps. Whole-field Scotopic Sensitivity Implements modified test of Glovinsky et al. No need for steady fixation or refractive correction. Results are relatively unaffected by mild cataract. Stimulus is 4 seconds of 1 Hz sinewave flicker.