Canon EOS rebel xs - Manual (Page 34)

Mounting and Detaching a Lens
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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.
While pressing the lens release
button, turn the lens as shown by
the arrow.
Turn the lens until it stops, then
detach it.
About Zooming
Detaching the Lens
Minimizing Dust
When changing lenses, do it in a place with minimal dust.
When storing the camera without a lens attached, be sure to attach the
body cap to the camera.
Remove dust on the body cap before attaching it.
Image Conversion Factor
Since the image size is smaller
than the 35mm film format, it will
look like the lens focal length is
increased by 1.6x.
Image size
(22.2 x 14.8mm / 0.87 x 0.58 in.)
35mm image size
(36 x 24mm / 1.42 x 0.94 in.)