Photography, like many activities, is often simplified with basic rules that, if followed, can help you capture nice images. These rules are not strictly accurate or reliable for every situation, but are based on practical experience and do provide reasonable results.
One rule that just about every photographer has heard is that you can hand hold your camera when you use a shutter speed that is at least “one, over the focal length” of the lens used. For example, if you have a 100mm lens, you can theoretically hand hold the camera using a shutter speed of at least 1/100 of a second.
Times have changed and I’d suggest that that rule should now be banished from your psyche.
Let’s think about this. Last year, Canon announced the Canon EOS R with a sensor of 30 MP. Nikon’s D850 sports a 45 MP sensor and in the next few weeks Sony will be releasing its new A7R with an astounding 61 MP sensor. Please, please - understand that there is so much more to a camera than just a megapixel rating.
The point is that the cameras used today have such incredibly high resolution that we can’t depend upon a “Rule of Thumb” that was developed for film. A typical 35mm film had about 18 million bits of silver in the emulsion - that would be equivalent to a 6 megapixel sensor.
Today, 1/100th of a second should be rock bottom on any normal lens. I’d suggest that from now on you plan on doubling the shutter speed that our old rule of thumb provides for you. You may find that your images come out a lot sharper.
Enjoy the journey.