His approach to portraiture was defined by a steady hand and a clear focus on the subject. In his self-portrait, Kamphuysen avoids the dramatic flourishes common in earlier Baroque styles. He uses a muted palette and precise brushwork to capture the texture of fabric and the subtle contours of the face. His work reflects the Neoclassical shift toward realism and restraint that defined the late eighteenth century.

Collectors today value Kamphuysen for the quiet authority of his compositions. His portraits provide a sense of history without the visual clutter of more ornate periods. Because he understood the requirements of domestic interiors, his prints scale well to different room sizes. They offer a connection to the Dutch tradition while maintaining a clean aesthetic.