Archaeological Photography – Lighting

One of the most crucial aspects to how we see the world – whether it be in home design or photography – is lighting.  Nearly everyone knows this – even if they didn’t realize it.  Anyone who has put a flashlight under their chin in the dark, knows that lighting from the bottom is “scary” because it is not the “normal” angle of light (which is from the top left).  This post will address a few aspects of lighting.

Archaeological studio photography is usually on the “macro” scale.  Macro, as most everyone by now knows, in  photography does not mean that one is taking pictures of large objects but small.  Macro actually refers to the ability to zoom in and make the small object large.  Often the largest a single macro setting can make an object is ½ the size of the object on film.  At this small scale, lighting is crucial to providing the ability to see the details of these tiny objects.

There are about five standard lighting methods that are useful in different situations – each depending on the object to be photographed.  Often more than one will be used depending on what you are photographing.

Axial – the lighting is on the angle of the camera

Reflected flash – helps send the light back at the object from the other side

Reflected underlight – illuminated under the object and reflected back to give an even light

Ring-flash – a flash that is like a donut around the lens and creates shadows around object evenly

Oblique – light from different angle other than camera

Angle of light is only one aspect.  Distance the light is from the object is also important.  A couple of inches movement can create drastic differences.  Also remember that the closer you are to the object, the less light you are getting during exposure.  Thus, as you increase the magnification (zoom) you need to also increase the time of exposure (if you want a crisp, detailed shot).  The formula is (m+1)².  Thus, if you have a 1:1 magnification, you will have to have an exposure of 4 times normal ((1+1)² = 4).  If you have a light meter this can help you find the right exposure time (if math is not your specialty).

The reason for this is a term called “The Circle of Confusion”, which is at .025mm.  As you zoom into a crisp photograph, when you get to .025mm the speck of detail is no longer a dot but a fuzzy ring.  This is why the depth of field at macro photography is a tricky thing to get right.  Longer exposure helps to give better details at a smaller size.

Another thing to keep in mind is that light also gives off different colors called “warmth”.  Since light has a temperature (moving from red to white to blue all measured in Kelvin) it matters what the source of light is and how “hot” that light is.  Different bulbs burn at different temperatures producing a variety of warmth (yellowing, whiting, or bluing affect).

One last cool tip…

It is standard to take most object photographs against a white background (easier digital object manipulation this way).  To get the best results shutter speed (which we will get into in the next photography post) needs to be adjusted for light.  A longer exposure will give a more white background (given that you are photographing your objects against a white background) and a shorter exposure to darken it (a graying effect).