Canon EOS Rebel T1i EOS REBEL T1i/EOS 500D Instruction Manual - Page 34

Attaching and Detaching a Lens About Zooming To zoom, turn the zoom ring on the lens with your fingers. If you want to zoom, do it before focusing. Turning the zoom ring after achieving focus may throw off the focus slightly. Detaching the Lens While pressing the lens release button, turn the lens as shown by the arrow. Turn the lens until it stops, then detach it. Attach the rear lens cap to the detached lens. To owners of the EF-S18-200mm f/3.5-5.6 IS kit lens: You can prevent the lens from extending out while you are carrying it around. Set the zoom ring to the 18mm wide-angle end, then slide the zoom ring lock lever to . The zoom ring can be locked only at the wide-angle end. Do not look at the sun directly through any lens. Doing so may cause loss of vision. If the front part (focusing ring) of the lens rotates during autofocusing, do not touch the rotating part. Image Conversion Factor Since the image sensor size is smaller than the 35mm film format, it will look like the lens focal length is increased by 1.6x. 34 Image sensor size (22.3 x 14.9 mm / 0.88 x 0.59 in.) 35mm image size (36 x 24 mm / 1.42 x 0.94 in.)