Most people can hand hold the camera when the shutter speed is 1/60th or faster.
It takes some practice and good technique to hand hold for shutter speeds as long as 1/15th of a second, but I would not recommend it if you want sharp images. You are likely to get blurry photos if you hand hold less than 1/60th.
The general rule of thumb is not to handhold if the shutter speed is below the focal length of the lens. So if you are using a 100mm lens, don’t hand hold below 1/100th of a second. If its a 50mm lens, don’t go below 1/50th of a second.
This is just a guide, and with practice (and the image stabilisation feature of some lenses), you could hand hold at slower shutter speeds. It also depends on what size the image will be reproduced. You can get away with some lack of sharpness if you are only displaying the image at small sizes.