To check density calibration, first zero the unit, then measure the "CAL" step on the transmission reference. If the measurement is within 0.02D of the densities specified , the unit is properly calibrated. Otherwise follow the step below to perform a full instrument calibration.Please note that there are several calibration options for the 369. This page outlines the 'long' calibration routine which views and allows edits (as required) of the stored reference data. To perform a full instrument calibration proceed as follows:
Locate the 5-step calibration standard (P/N 339-68). Notice that step #4 is marked with the word "CAL". Also note that the ANSI traceable values for this step are hand-written below each film target. Handle the transmission reference at the edges only. Fingerprints or any other foreign substances on the measurement area will cause errors. Attempts to dust or clean the surface with anything other than a soft camel hair brush may change densities. Minimize change by storing in a dark, cool, dry place.
The word "CAL" is printed on the 369. It is located between the "FUNCTION" and "COLOR" keys at the rear of the measurement arm. To begin the calibration routine, press both of these keys at the same time - then release.
The prompt "N cal Y" will appear. The "N" reply is associated with the "FUNCTION" key and the "Y" reply with the "ZERO" key (notice the words silk-screened beneath the densitometer's display panel).
Answer "Y" to the above prompt by pressing the"ZERO" key.
The prompt "N Qcal Y" will appear. "Qcal" is short for Quick CalTM. We do not want the Quick Cal routine. To continue then, press the "FUNCTION" key to answer "N".
The densitometer will briefly display "SET H"' and will then show the number currently programmed for the "CAL" step. It begins with the Visual (v) channel.
Confirm that the displayed number matches the Visual value printed on the calibration standard. If it does NOT match the stored valued must be edited (refer to Editing the Stored Numbers under Related Support).
When the number matches, press the "COLOR" key one time to advance the calibration routine to the next step. The densitometer will now display the valued stored in the Ultraviolet channel. Again ensure that this number matches the value printed on the calibration standard film.
Press the "COLOR" key again to advance to the next step. The densitometer will now prompt "READ AIR". Press the "READ" button down firmly and hold until a number is shown on the display panel.
When you release the button the densitometer will display "READ HI". Locate the calibration standard film beneath the probe. Ensure that the "CAL" step is centered beneath the instrument's aperture.
Again press the "READ" button firmly and wait until a number is displayed. That's it! The densitometer is now properly calibrated for both the Visual and the Ultraviolet measurement channels.