Microscope objectives, machine vision lenses, metrology objectives, and lithography optics are the most common articles classified here. The distinguishing factor is that these lenses are not designed for cameras, projectors, or photographic enlargers—they serve scientific, industrial, or semiconductor manufacturing functions. If the intended instrument is a camera or projector, the more specific heading for those instruments applies.

No. Whether the objective contains a single element or a complex multi-element design, the classification is determined by the mounted condition and the intended application, not by the internal optical construction. However, the number of elements and the optical design may be relevant for valuation and for determining whether the article qualifies as a complete instrument versus a component.