Canon EOS Rebel T1i EOS REBEL T1i/EOS 500D Instruction Manual - Page 60

Z: Changing the ISO SpeedN Set the ISO speed (image sensor's sensitivity to light) to suit the ambient light level. In the Basic Zone modes, the ISO speed is set automatically (p.61). 1 Press the button. (9) X [ISO speed] will appear. 2 Select the ISO speed. Turn the dial or press the key to select the ISO speed. You can also set the ISO speed in the viewfinder while turning the dial. With "AUTO" selected, the ISO speed will be set automatically (p.61). ISO Speed Guide ISO Speed 100 - 200 400 - 800 1600 - 6400, H Shooting Situation (No flash) Sunny outdoors Overcast skies, evening Dark indoors or night Flash Range The higher the ISO speed, the farther the flash range will be (p.62). In the [7 Custom Functions (C.Fn)] menu, if [Highlight tone priority] is set to [1: Enable], ISO 100, ISO 6400 and "H" (equivalent to ISO 12800) settings cannot be set (p.186). Using a high ISO speed or shooting in high-temperature conditions may result in more grainy images. Long exposures can also cause irregular colors in the image. When you shoot at high ISO speeds, noise (horizontal banding, light dots, etc.) may appear. Under the [7 Custom Functions (C.Fn)] menu, if [ISO expansion] is set to [1: On], ISO 6400 and "H" (ISO 12800) can also be set (p.184). 60