Both fall under heading 9011, but in different subheadings. Stereoscopic microscopes (901110) use two separate optical paths to produce a three-dimensional image at lower magnification, while compound optical microscopes (901180) use a single optical path with multiple lenses for high-magnification two-dimensional imaging. The distinction matters for duty-rate purposes at the 6-digit level.

Camera attachments and adapters designed specifically for compound optical microscopes are classified as accessories under 901190 rather than as photographic equipment, because they are purpose-built for the microscope system. Generic camera bodies that happen to be mounted on a microscope may classify differently; a binding ruling is advisable for ambiguous configurations.