• Flat Copy Flat Copy

    Document copy

    You can copy documents by scanning with various levels of sophistication. With delicate documents photographic reproduction using a camera is often preferable to drums or flatbed scanners.

    Document copying is one of the most straightforward of lighting set-ups and can comfortably be achieved.

    Here we see an example of simple copying of a non-reflective surface. The wonderful image is from an early 20th century book illustrated by Arthur Rackham.

  • In situ copy - tricky In situ copy - tricky

    Behind Glass

    Sometimes it is not possible either to remove an object for photographic copying or place it in an ideal position and so you need to photograph in situ. Worse still is when you are faced with a flat object such as a painting behind curved glass.

    The object to the right is a strange mixture. The frame is a black lacquer mourning frame with gilt bronze mounts and trim. It probably dates from the late Victorian period. However the curiosity is the picture. This is a fragile miniature on ivory and dates from the 18th century. The whole sits behind a CURVED glass front as illustrated (right).

    The reflections and distortions are removed by using highly powerful but oblique lighting and ensuring the plane of the ivory and the plane of the sensor in the camera are parallel. The gilt mount is out of true in real life!

    Here we are fortunate that the combination of lighting and angles just about permits us to take this shot. Sometimes we have to composite more than one image and that can be very time consuming when it comes to balancing light and colour.

  • Principles Principles

    Copy lighting

    Copy lighting is very straightforward for flat subjects. Two light sources are mounted opposite one another equidistant from the subject and typically at 45 degrees to it (not so critical). The axis of the camera is placed perpendicular to, and with the sensor parallel to the plane of the subject to be copied.

    Life gets more difficult with uneven and reflective subjects. The idea of the standard set up is that the angle of incidence of the light is set so the collecting family of angles from the lens does not collect any directly reflected specular light. But when the surface is uneven there are many angles formed on the surface. Some angles will be coincident with the lens. In the previous example with a smooth concave glass by setting the lighting angle appropriately and with enough lighting power you can illuminate without reflection. With a rough reflective surface you are bound to get some reflection.

    The way around this is to polarize the light from the light source and have a crossed polar on the lens. This will minimise polarized reflections. This not a universal panacea but helps on a lot of occasions.