Imaging Techniques

Graphics Atlas uses a variety of imaging techniques, including a standardized set for the compare section, to emphasize the unique attributes of each print. Outlined below are several points of interest meant to clarify the techniques and magnifications.

Example of axial illumination setup on copystand

Example of raking illumination setup on copystand

1: Digital SLR Camera
2: 50% Transmittance - 50% Reflectance Plate Beam Splitter
(Half Silvered Mirror)
3: Fiber Optic Gooseneck Light
4: Vacuum Easel

1: Digital SLR Camera
2: Fiber Optic Light Line
3: Vacuum Easel

Effects of Axial and Raking Illumination

Our axial lighting setup is used to induce and document specular reflectance off the surface of a print, and thus gauge gloss. Glossy prints will show a concentrated circle of specular reflection, while matte prints will scatter the light and merely appear illuminated.

Our raking light setup is used to show surface texture, a feature that can provide a great deal of information; particularly with 20th century photographs where texture was intentionally applied during manufacture.

Analogous Magnifications

To make Graphics Atlas more applicable to everyday examination, two magnifications on were chosen to reflect commonly found optical tools.

The 4th block of magnification is comparable to that of 10x loupe.

The 5th block of magnification is comparable to that of a 30x pocket microscope.

Brightfield Reflected Light Microscopy

Due to scale and differences between the equipment, axial and 45-degree lighting in the microscope must be accomplished in a different manner from that used on the copystand.

45-degree illumination in the compound microscope is simulated through cross-polarization (the axes of the analyzer and polarizer are aligned perpendicular to one another).

Axial illumination in the compound microscope is accomplished by aligning the axes of the analyzer and the polarizer.