Mirage — rebadged 135mm f/2.8 manual telephoto prime, sold across vintage SLR mounts
Mirage was one of the anonymous house brands filling UK and European camera-shop lens racks through the 1970s and into the 1980s, rebadging Japanese-made optics for retailers wanting their own label without running a factory. The 135mm f/2.8 telephoto prime was a typical entry from that trade.
Like most brands in this trade-name category, the Mirage 135mm f/2.8 was contracted to a Japanese optical manufacturer and sold as a manual-focus, manual-aperture prime across common SLR mounts of the period, letting the retailer stock one design against multiple camera brands. Specific optical construction, weight and filter size are not confirmed from available sources.
Performance sits with the general run of independent 1970s telephotos: soft wide open, sharpening from around f/5.6, with lower contrast and greater flare sensitivity typical of lenses without advanced multi-coating.
Mirage-branded lenses are inexpensive but inconsistent in condition secondhand, since the name covers output from more than one factory. Check the aperture detents, inspect for fungus, and confirm the mount fitted is correct.