The Rule of Thumb for Handholding

To ensure steady shots without a stabilizer incorporated, the rule to use is:
Shutter spead should be equal or faster than 1/F seconds, where F is the equivalent focal lens.

Example: Shooting in 36mm eqv. without stabilizer, needs about 1/36 seconds for a stable shoot.

Of course we are talking about using your hands for taking the shot, using tripod will open the range till the maximum shutter speed and zoom-in your gears allow.