Photax — budget manual-focus 28mm f/2.8 wide-angle prime, M42 and bayonet SLR fittings
Photax was a UK house brand of the 1970s-1980s, used by photographic retailers to sell budget Japanese-made optics alongside own-label cameras and accessories. The 28mm f/2.8 was a wide-angle step-up lens for SLR owners moving beyond a standard 50mm kit lens.
Focus and aperture are set by hand via knurled metal rings, with a click-stopped iris diaphragm typical of manual optics of the era. It was offered in universal M42 screw mount and bayonet versions fitting major SLR systems of the time. Element count, coating, weight and filter thread are unconfirmed and omitted rather than guessed.
A budget 28mm f/2.8 of this vintage typically shows moderate contrast and softer corners wide open, sharpening by f/5.6-f/8. Rendering sits closer to contemporaneous own-brand mail-order lenses than first-party Nikon, Pentax or Canon wide-angles, suiting travel and general shots more than architectural work.
Examples circulate mainly through camera fairs and online auctions rather than specialist dealers, priced low given the house-brand origin. Check the aperture blades move cleanly, mount threads or bayonet lugs are undamaged, and glass is free of fungus or haze before adapting to a mirrorless body.