Phago's budget enlarging lens — the basic 50mm at minimum specification.
Phago was a lesser-known European manufacturer of darkroom accessories and optics, producing budget-grade enlarging lenses for the amateur market. The 50mm f/4.5 follows the standard design for 35mm negative enlarging, with a slower maximum aperture than premium offerings.
50mm focal length, f/4.5 maximum aperture, M39 thread mount (presumed), basic anti-reflection coating, designed for 35mm negatives.
The relatively slow f/4.5 maximum aperture makes focusing under the enlarger less convenient than f/2.8 or f/3.5 alternatives. Optical quality is entry-level, suitable for basic black-and-white printing where precision is not critical.
Inspect optics carefully; budget-grade lenses are more susceptible to coating degradation, haze, and fungus. Check aperture blades and thread engagement.