Calibration: X-Rite sensitometers are calibrated at the factory using exposure setting #3. The exposed density of Step #11 is adjusted to match a factory standard instrument maintained by X-Rite. As calibration requires a master instrument for comparison, sensitometers do not have user accessible calibration adjustments. X-Rite offers a recertification program to verify sensitometer calibration. Recertification (factory recalibration) is recommended every 12 months and can be arranged through X-Rite's Instrument Services Department. Selecting Exposure Color: The film manufacturer will recommend the proper color light to expose the film. Select the same color as is emitted from the intensifying screen. When using a Blue emitting intensifying screen-- use the "BLUE" position. When using a Green emitting intensifying screen--use "GREEN". Adjusting Exposure Setting: The 383 sensitometer has seven possible exposure settings for both Blue and Green films. The factory preset exposure setting is #3. If different exposure times are required, refer to the chart below. Each exposure setting will move the speed index on the film approximately one step (log 0.15D). The DIP SWITCH used to change the exposure is located on the bottom of the unit. There are eight individual switches in the DIP SWITCH. The first four of these (left-hand) are used to adjust BLUE exposures. The remaining four (right-hand) adjust GREEN.