This is
a metallic exposure box with electronic timer to control the exposure time. The
exposure time can be adjusted continuously from 0.1 to 5 seconds. Provided with
binding posts for calibrating the exposure time setting using chronoscope. It
has two card holders, one for the standard card - 3.5" X 5.5" and
another for big size cards - 6" X 8". Works on 230 V AC. Supplied
with Dot Cards for span of attention.
Other type of cards for span of Apprehension can be ordered
extra.
