Microprocessor Photo Colorimeter ? 1312 is a compact and easy to operate instrument for Photo Colorimeter analysis of any concentration. The output is available on a 16 x 2 line alphanumeric backlit LCD display in terms of %Transmission (%T), Absorbance (Abs.), Concentration (Conc.), and KFactor. This instrument has 100 sample storage memory and printer output facility for printing data with any dot matrix printer. The use of microcontroller has made it extremely versatile and accurate instrument. 10 mm pathlength matched test tubes are used for sample and blank. Facility has been provided to store the last KFactor and the standard concentration value. User can also enter any known ?Factor? for a test, thereby eliminating the need to re-run the standards again and again The use of high class standard wide range glass filters covering 400 to 700 nm give extremely good results. The filter setting is controlled by a rotating disc having 8 filters. An automatic shutter is provided to stop the light reaching the photocell, when test tube is not inserted in the tube holder. This increases the life of photocell tremendously.