As described in Chapter 6, the skeleton is divided into axial and appendicular portions (see Figures 6.1 and 7.1). The axial skeleton is structured from 80 bones segregated intothree major regions: the skull, vertebral column, and thoraciccage (Figure 7.1) . This part of the skeleton (1) forms the lon-gitudinal axis of the body, (2) supports the head, neck, and Chapter 7 The Skeleton 199 7 Figure 7.1 The human skeleton.
Above: Some cameras have a switch to set it to auto or manual focus. Manual focus, meanwhile, disables autofocus and enables you to adjust it yourself. This is useful when the focusing system can't find focus for whatever reason, such as when it's too dark or when there's little contrast in the scene.
Canon also sold a manual-focus camera, the Canon EF-M, which used the same EF lens mount as the EOS cameras. It came with all the automatic and manual exposure functions but lacked autofocus. It came equipped with a split-screen/microprism focusing screen for precise manual focusing.he release of the 5D MkIII gave Canon the lead once again in this category; previously, its top-line cameras had 45 AF points, which led the industry until Nikon released its D3 and D300 DSLRs with 51-point AF systems.