There is always more to a painting than first meets the eye. Sometimes, however, our eyes alone are not good enough to see all of the detail that exists in a fine piece of art. Microphotography is the art and science of highly magnified photography and it is an important tool in the forensic analysis of paintings and other artworks. While a forgery may look perfect to the naked eye, a host of details that can only be seen under magnification can quickly expose a fraud.

Almost any camera, film or digital, color or black and white, can be used for microphotography. The important piece of equipment with this analysis method is the microscope that provides the image magnification.

A binocular microscope on a traveling stage allows for inspection of larger pieces of artwork.

The correct type of microscope will have adapters to connect popular camera bodies directly to the ocular piece of the microscope with minimal distortion and at the correct focal length. Almost as important is the frame of the microscope; it should provide easy movement across the surface of the artwork without disturbing the sometimes delicate specimens.

Finally, the microscope or the workspace should have not only sufficient lighting, but very directional lighting. For microphotography, different features become apparent on the surface of the painting when it is illuminated from different angles. Bright fiber optic lights can provide both raking, (highly oblique lighting from close to the surface of the painting), and diffuse overhead lighting, depending on the painting features that need to be illuminated.

There are a number of different ways that microphotography is used in the analysis of artwork. One of the primary uses of microphotography is in simply having a definitive, detailed image of the painting prior to any conservation work. These highly detailed images also provide an ongoing database of historical images that may pinpoint changes in the artwork over time. microphotography can also, with the use of raking lighting, show surface topology details that can give information on the way the paint was applied to the artwork.

Lucas Cranach, Adam and Eve. The magnified image shows the tiny date painted onto the trunk of the tree.

Lucas Cranach, Apollo and Diana. The magnified image shows the reflections in the stag's eye.

With higher magnification, microphotography is used to do analysis of brushstroke style. By developing a database of brushwork styles art historians can gain a better understanding of which artists may have contributed to a particular piece that was created in some of the larger shops. This information can also help to detect forgeries.

Just as useful is the study of crack and loss morphology in the artwork. As an authentication tool this analysis is extremely useful, as it is very difficult to fake damage to an artwork that looks correct under magnification.

The left image shows the natural cracks in a 15th century painting. The right image shows incised cuts in an alleged 15th century painting Madonna and Child, Umbrian School. Images are with x100 magnification.

Additionally, some cracks and losses may be large enough that layer information can be seen within the damaged area, giving clues to the way the artist built up the painting. Under the highest magnification, between x40 and x100, pigment identification is also possible by detecting differences in the granularity of different materials.

Of course, microphotography is only so useful. The biggest limitation is that microphotography is strictly a surface analysis technique; apart from sometimes serendipitous crack analysis, it can tell you nothing about what is happening behind the paint or varnish. This is why, for any complete analysis, microphotography always has to be paired with a penetrative technique such as X-Ray imaging or infrared reflectography.

Secondly, a typical thorough microphotography analysis has to be done ex situ; providing for the correct angle of lighting usually means that the artwork cannot be under glass. Finally, depending on the final magnification desired, and the total size of the artwork being imaged, microphotography can be an extremely lengthy process.

Microphotography
Pros	Cons
Relatively inexpensive forensic method	Strictly a surface technique
Allows for the study of crack morphology	Can be an extremely lengthy process depending on magnification and size of artwork
Potential pigment identification through granularity analysis
Can potentially provide information on brushstrokes and fingerprints for artist identification

Since microscopes and fiber optic lighting are reasonably inexpensive, and almost any camera can be used, even smaller labs can use this technique for forensic analysis of artwork. Of course, the more you spend, the higher the magnification and the finer the detail you can extract, but there is a limiting scale to how useful higher magnification can be with forensic microphotography.