Both kit lenses sold with the Canon EOS 70D offer image stabilization, indicated by the initials IS in the lens name. Image stabilization attempts to compensate for small amounts of camera shake that are common when photographers handhold their cameras and use a slow shutter speed, a lens with a long focal length, or both. Camera shake can result in blurry images, even when your focus is dead-on. Although image stabilization can’t work miracles, it enables most people to capture sharp handheld shots in many situations that they otherwise couldn’t. The feature works regardless of whether you use autofocusing or manual focusing, and it works for both still photography and movie shooting.
However, when you use a tripod, the system may try to adjust for movement that isn’t actually occurring. Although this problem shouldn't be an issue with most Canon IS lenses, if you do see blurry images while using a tripod, try setting the Image Stabilizer (IS) switch (shown in the figure below) to Off. You also can save battery power by turning off image stabilization when you use a tripod. If you use a monopod, leave image stabilization turned on so it can help compensate for any accidental movement of the monopod. If you shoot in the B (Bulb) mode, Canon recommends that you disable stabilization.
On non-Canon lenses, image stabilization may go by another name: anti-shake, vibration compensation, and so on. In some cases, the manufacturers recommend that you leave the system turned on or select a special setting when you use a tripod, so check the lens manual for information.
Whatever lens you use, image stabilization isn’t meant to eliminate the blur that can occur when your subject moves during the exposure. That's a problem related to shutter speed.