The default Illuminant Setting on a CR-400 Series Chroma Meter (Colorimeter) as described by the CIE Norms is Illuminant C.
The optional Illuminant is D65.
What is the difference? Details can be seen on the Illuminant link above, but broadly speaking we can say that both Illuminants emulate the Spectral Reflectance Curve of natural daylight. The prime difference is that C excludes Ultra Violet (UV) Spectra while D65 includes UV.
These images demonstrate that while the average Spectral Curves are similar, D65 contains data below 400nm while the C does not. There are also some differences in the Visual Range.
For precise comparison of readings, the same CONDITIONS are required to compare Apples to Apples, so typically data collected under one Illuminant does not fully compare to data collected under D65 condition setting.
In reality as can be seen from a real life measurement, if the same colours are measured, the values are quite close.
- However it is impossible to visualise what 0.07 to 0.01 means visually, so to avoid confusion, the same Conditions must be used in all cases.
- The difference will vary to a greater or lesser degree depending on the actual colour.
- The CR-400 Series, unlike Spectrophotometers can not actually MEASURE UV, so using D65 is a convention, not a Technical Requirement.
How to change your Instrument Illuminant Settings form C to D65 – Scenario 1
If you are using a CR400 Series Measurement Head in stand alone mode with batteries, it is NOT possible to change the settings.
Scenario 2 – Manual Initialise
Connect the Measurement Head to the DP Data Processor with the supplied cable.
This procedure is clearly explained in the supplied manual.
(If you no longer have the manual, download a free PDF version on the Narich Website under Resources – Open Resources – Manuals.)
AT THIS POINT NOTE THAT PROCEEDING WILL ERASE ALL DATA ON THE DP AS WELL AS ALL SETTINGS BACK TO FACTORY DEFAULT
Hold Key #2 (Delete / Undo) and at the same time switch the Power Switch ON.
Screen Details as per Page 76 of the manual. (See images below for steps)
Screen 1 – First Screen request: Do you wish to Initialise OK?
Select OK using BLUE Measure / Enter button
Select the bottom centre button: Index Set
Screen 3 – The Option Settings Screen opens
Using the Δ (Arrow Keys) move the Triangular Indicator down to Illuminant C
Select Illuminant D65 using BLUE Measure / Enter button
Screen 4 – Illuminant D65 is now selected.
Select the bottom left button ESC and save the selection
Screens of BEFORE and AFTER Saved Result
Scenario 3 – Software Initialise – Utility Software
It is possible to change the Illuminant from C to D65 with software alone (No DP Processor) but you HAVE to initialise the Head first.
This will result in a LOSS OF DATA
We suggest that all data is BACKED UP first
Screen 1 – Head indicates setting is C
Before connecting the Measuring Head to the Utility Software, it is set to Illuminant C
Connect the instrument as described in the manual. The Measuring Head must be in PC Mode.
Screen 2 – Instrument Settings / Options.
Select the INSTRUMENT button, SETTINGS and the OPTIONS Tab
It will appear possible to select the Illuminant D 65 Setting.
Without Initialising, this process will fail
Screen 3 – Attempting to change without initializing
A warning screen requires Initialising
Data WILL BE LOST
Screen 4 – Initialising
Select INTSRUMENT, INITIALISE and select OK
DATA will be LOST
Screen 5 – Reset Successful
Illuminant D65 has now been set.
The system however still has the Calibration data for the previous Illuminant C setting
This has to be updated for the measurements to be correct.
Screen 6 – Error Message – No Calibration Data
Fortunately the Utility Software warns that Calibration data is required.
Screen 7 – Edit Calibration Data
Enter the Y x y data for the Appropriate Illuminant (In this case D65) and enter OK
The NEXT Screen will say PERFORM CALIBRATION. NOTE
Place the calibration to be read by the Instrument BEFORE pressing OK as a measurement takes place immediately.
If the calibration data is missing it will ask to be re-entered at this stage.
Make sure to select VALUES from the D65 (In this case) row and NOT Illuminant C values
Screen 8 – Confirmation
If the Measuring Head is now disconnected form the Utility Software, the D (In a square) symbol on the bottom left of the screen confirms that the Illuminant D65 has been set correctly and you are ready to work.
Scenario 4 – SpectraMagic NX Software ( CM-S100w 2.70.0006 version) Older versions and later versions will likely be identical.
As advanced software the process is very simple.
- Back up all data on a Template
- Select Instrument / Standalone Configuration / Initialise. You will receive a WARNING as all DATA will be LOST
3. Press OK . The reset will be CONFIRMED as OK.
4. Selecting CALIBRATION will result in the warning NO CALIBRATION DATA
5. Select OK and then EDIT on the screen that appears.
6. Insert the appropriate data for the appropriate Illuminant and continue.
7. Perform Calibration. Make sure TILE is in place
8. Completed successfully
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