The Kodak Gray Card Plus helps you establish grading which best maintains the lighting in the original film. That can save considerable time and take the guesswork out of wondering, "How is this scene supposed to look?"
The card is also the standard reference for the Kodak telecine exposure calibration (TEC) film which gives you transfer points - objective exposure information for the Cinematographer.
Using the Kodak Gray Card Plus as a Grading Reference
Always grade the center portion of the card to 18% neutral grey. That will give you a good grading reference to transfer the scene(s) that follow.
- Center the controls using Kodak telecine analysis film or other baseline reference.
- Locate the first shot of the Kodak Gray Card Plus. Roll into the shot to make sure the lighting does not change.
- Set the voltages or IRE values for the white, grey and black areas of the card to those indicated below.
- Use these settings for grading the scenes referenced by the grey card. Make corrections, if needed, to improve overall color and contrast.
- Store the settings so that they may be recalled for future use.
- Proceed to the next card and set up accordingly.
Grading Values for Kodak Gray Card Plus - normal exposure (component values)
Note: The values specified in the voltage and IRE tables are all COMPONENT RGB values with no setup. The IRE values indicated are percentages of component RGB voltages.
Values are based on 0-700 mV equal to 0-100% of voltage.
| ||Component Voltage ||Component % Voltage |
|White ||560 mv ||80 |
|Gray ||320 mv ||45 |
|Black ||140 mv ||20 |
Note: If the Cinematographer has designed special lighting e.g., colored gels, fire, low-key, etc, or used special lens filters, the lighting on the card will not match the scene. However, grading the grey portion of the card to 18% neutral will help to maintain the desired effect in the transfer.
Using the Kodak Gray Card Plus as a Reference to Determine Transfer Points
The following are basic procedures for using the grey card with the Kodak telecine exposure calibration (TEC) film. Consult the TEC film user's guide for complete instructions.
- Locate the first shot of the grey card on the roll of negative to be transferred.
- Recall the TEC film settings previously stored in memory.
- Read the red, green and blue values on the waveform monitor from the grey portion of the card.
Note: Do not zoom in or change the size of the grey card.
- Convert these voltages or IRE values to transfer points using the TEC film conversion table or automatic reading system.
A normally exposed 18% grey card has RGB transfer points of 25-25-25. You can now assess exposures in much the same way a timer uses printer points. One t-stop is equal to about 7 printer points or 7 transfer points. Commonly understood exposure relationships are, therefore, maintained.
Note: If the card has been shot as a reference for darker or lighter grading or special lighting and exposure control, the card will not be an accurate reference for determining transfer points. In these cases the cinematographer is instructed to shoot the card a second time and identify it as an exposure reference.