A vintage Minolta E.Rokkor 50mm f/4.5 lens, likely for enlarging.
The Minolta E.Rokkor 50mm f/4.5 is a Minolta-branded enlarger lens designed for darkroom printing from 35mm negatives. The 'E.Rokkor' designation follows Minolta's naming convention: E = Enlarger, Rokkor = Minolta's premium lens series. At 50mm, it is optimised for printing at the standard enlargement ratios used for 35mm film.
50mm focal length, f/4.5 maximum aperture, flat-field corrected for enlarger use, M39 enlarger thread mount, 4-element optical design, manual iris for exposure time control.
The E.Rokkor series sits above generic enlarger lenses in Minolta's darkroom product line. The 50mm f/4.5 is optimised for printing standard 8×10" enlargements from 35mm negatives. In modern use, E.Rokkor lenses are popular for macro photography via bellows — the flat-field correction that makes them excellent for printing also produces sharp, uniform close-up images.
Inspect all elements for haze and fungus — enlarger lenses in darkroom use are exposed to chemical fumes and humidity. Check iris blades for oil contamination. Test the aperture ring. Verify M39 thread condition. When adapted to bellows, the 50mm f/4.5 should produce sharp flat-field results.