Grey card, matt surface, perfect neutrality, 18% reflectancy, 10x13cm (GC18S)

The gray card is a tool for determining the lighting conditions on the stage. It is neutral gray, size 10x13cm, on a solid surface.

Gray calibration cards are suitable for:

• determining the correct exposure
• measuring the contrast of the scene lighting
• color balancing in duplication procedures

Protect the card from moisture, dust, light and especially mechanical damage.

Instruction for use of Gray 18% calibration table 10x13cm GC18S

A) EXPOSURE DETERMINATION 

Place the grey card so that it received the same light as your subject, without shadows and glares on card itself. Measure the exposure either by camera with built-in exposure meter, or by hand meter from the distance approx. 7 cm. When measuring, avoid cast-ing a shadow on the card. 

• For artificial light, place the card close to the subject, aimed between the main light and camera. 
• For daylight place the card in front of the subject, pointing at the camera. You can mea-sure the exposure with the card near your camera; be sure, that the card is in the same relationship to the light source as the subject. 
• If the subject is very dark, increase measured exposure by 1 /2 or 1 stop; for very light subject decrease the exposure to the same extent. 

B) COLOUR BALANCING 

Optimal reproduction of the grey card is not absolute neutral grey in all cases. Cameras often do not reproduce a neutral grey precise when everything else is balanced properly. Place grey card in your scene as a reference that records the colour of illuminator. Take a shot. Open your grey card image in Photoshop. 
Click IMAGE > ADJUSTMENT > LEVELS. Double click on the middle eye dropper (SET GREY POINT), set levels R=G=B=128, save the settings. 
Position the eye dropper over the grey card and click. You should see an instant improve-ment in colour. Leave the LEVELS dialogue box open, then click on SAVE. Use this saved "Custom Colour Balance" for all shots taken under the same lighting conditions 

C) SETTING THE WHITE BALANCE 

Reverse side of the grey card is white (reflectance 90%, L*a*b* coordinates: L*=96, a*=1, b*-1). You can use white side for white balancing before taking a shot (preset): 

• Set the White Balance switch on your camera to appropriate position (Custom/PRE). Arrange your chart in the same way as (A), but turn the chart by WHITE side towards the camera. Measure white readings and save them to "white memory" of the camera. 
• Use this "Custom White Balance" for all shots taken under the same lighting conditions.