I have bought a HOYA circular polarizer filter 58mm (CIR-PL) for the Canon EF 50mm f1.4 (said to be 58mm filter size). But the filter doesn't fit. Did I miss something? It doesn't even fit on a 18-55 kit lens (Yeah I know that filter isn't useful on that lens....but still).
Mine (same lens and filter) works just fine BUT, its very picky about initially threading the filter onto the lens mount, the thread tolerances are very close. If you can't get it to screw on properly try another filter. If that won't thread properly get a magnifying glass and check both the lens and the filter threads to see if they're damaged/bent from cross-threading. If the lens mount has been crosstreaded you may be SOL for using filters on that lens.