To illustrate - During a circular dance, with everyone moving from left to right in concentric circles, the photojournalist usually rotates with the subject he or she is trying to photograph by panning the camera, moving it crosswise across the scene to increase background blur and subject sharpness. To get the desired effect, the photographer will move from left to right while the subject moves from right to left, freezing them out with the flash and leaving the surrounding party as a blur. One of the main keys to successfully capturing these photos is using the rear-curtain sync feature on the camera, which makes the flash go off at the end of the exposure rather than at the beginning. This allows the camera to record motion and then stop it at the end with the flash.
Conversely, with front-curtain sync, when the flash turns off first and then the camera picks up motion, it can distort the moment you try to stop.
GOING TO FLASH.
Dragging the shutter can allow you to use blur to your advantage, creating the effect of an object crossing your path. This helps capture the sense of motion, an effect usually seen in professional auto racing photos. Otherwise, taking a photo with enough speed to stop the action results in an image that lacks the same dynamic atmosphere.
Of course, the longer focal length of a long lens increases the likelihood of noticeable camera shake and blur at slower shutter speeds, which can sometimes be creatively desirable. Generally speaking, a 50mm lens should be used with a shutter speed of at least 1 / 50th of a second to produce a sharp image. Moving slower than that will probably result in motion blur, whether desirable or not. The 24mm lens has the same effect at about 1/225th of a second; the 100mm lens at 1/2100th of a second. Some tara wedding photographers at https://taraweddings.ca/wedding-videography/ even try to reduce the shutter speed to 1 / 15 seconds or slower with a 24mm lens or to at least 1 / 60 seconds with a longer lens to create maximum blur.
During a typical wedding day, many moments can make perfect use of this technique; from the bride's hasty preparations at home to members of the bridal party walking down the aisle, to the newly crowned couple walking out of the church as husband and wife for the first time. In any of these cases, panning the camera along the path of your subject will create that stunning "frozen in time" effect, complete with a blurry background of motion. When editing your shot, keep as much of the motion-filled background as possible, as this is really what gives the moment life and a sense of place.
Panning the camera around the scene at slow shutter speed also turns any light source, be it candles or light bulbs, into streaks of light that can create some interesting effects. Turning the camera in a circle during a long exposure produces circular bands of light. Another trick worth trying is to zoom in and out when the shutter is open, which can create some fun effects. Experiment, but realize that some techniques can be difficult to keep up with the plan.