Originally posted by Slon I have 3 yellow light lamps (basic light) that I can attach readily anywhere. I also have a UV lamp.You mean perpendicular?How does one use a gray card?
Regular tungsten bulbs are fine. You might need high wattage bulbs. I used use two 250w bulbs.
Sorry, film plane patallel to the surface below which is equal to the lens beeing perpendicular the the surface.
Probably I am not the best person to explain the 18%gray card but I will give a go. Camera exposure system is based on light reflected from a 18% gray. Metering should be done based on amount of light that is available. Grey card send back/reflects exact amount of light that is available. You probably have seen light meter placed at the face of a model to measure available light from the flash not what is reflected off the face.
Gray card: Place it where the document is going to be and set the proper exposure. You should be able to use the same exposure obtained with the gray card for light or dark pages.
Color reference patch : Take a test shot and adjust the white balance until the colors of the reference patch from the image matches the color of actual reference patch.
Personally I do not see the need to include the color reference patch for every frame. Once set, exposure and white balance should not change in a controlled environment. If you move the tripod or lights, you should recalibrate all over again. That is why if you are going to do this more than once copy stand will come in handy. There is no need to recalibrate anything unless the bulb changes.
Nico
(if my description of the gray card is incorrect in any way, please feel free to correct me. Thanks)