When Canon had the 1D line split, some of those cameras were APS-H. If the body designation was 1D, it had the APS-H sensor. These were marketed more for sports and wildlife photographers. With those bodies having the high speed shutters, faster AF, etc. Then Canon had the 1Ds bodies which were full frame. Aimed at portrait, fashion, and wedding photographers. Although the 1D bodies also worked very well for portraits, etc.