Canon EOS Rebel T1i EOS REBEL T1i/EOS 500D Instruction Manual - Page 184

3 Custom Function SettingsN Custom Functions are organized into four groups based on the function type: C.Fn I: Exposure, C.Fn II: Image, C.Fn III: Auto focus/Drive, C.Fn IV: Operation/Others. C.Fn I: Exposure C.Fn-1 Exposure level increments 0: 1/3-stop 1: 1/2-stop Sets 1/2-stop increments for the shutter speed, aperture, exposure compensation, AEB, flash exposure compensation, etc. Effective when you prefer to control the exposure in less fine increments than 1/3-stop increments. The exposure level will be displayed in the viewfinder and on the LCD monitor as shown below. C.Fn-2 ISO expansion 0: Off 1: On Enables ISO 6400 and H (equivalent to ISO 12800) to be set. However, if [C.Fn-6: Highlight tone priority] is set to [1: Enable], ISO 6400 and "H" cannot be set. C.Fn-3 Flash sync. speed in Av (Aperture-priority AE) mode 0: Auto The flash sync speed is set automatically within a range of 1/200 sec. to 30 sec. to suit the scene's brightness. 1: 1/200-1/60 sec. auto When flash is used with aperture-priority AE (f), this prevents a slow flash-sync speed from being set automatically in low-light conditions. It is effective for preventing subject blur and camera shake. However, while the subject will be properly exposed with the flash, the background will come out dark. 2: 1/200 sec. (fixed) The flash-sync speed is fixed to 1/200 sec. This more effectively prevents subject blur and camera shake than with setting 1. However, the background will come out darker than with setting 1. 184