Boyer Saphir Apochromatique 10/300mm | Camera lens

Boyer Apo-Saphir 300 mm f/10 (French manufacturing) – Brass construction
An old and rare apochromatic (Apo) lens, signed Boyer.
Boyer Paris Apo-Saphir 1:10 f=300 mm. In excellent condition; the lens surface treatment is superb.
Under bright light, slight traces of fungus are visible in the glass reflections.
The diaphragm blades operate correctly and the lens is fully operational.
The Boyer 'Apo-Saphir' line is renowned for its exceptional quality; it is described as corrosion- and immersion-resistant, and designed for scientific research.