Dave Sims , Sep 05, 2009; 05:01 p.m.
Bob, hi. Early A-1s and AE-1s were supplied with pre-1979 'breechlock' lenses, with a white alloy retaining ring. Later cameras were supplied with the so-called 'FDn' lenses with a bayonet-like fitting.
This is relevant to you, because if you have breechlock lenses, they have a 55mm filter diameter, and will take the BS-55 lens hood, which is easy to find. If you have FDn lenses, they take 52mm attachments and you need the BS-52 hood, which is a little scarce.