Happy Birthday America! #441
About the creation of this picture:
The shutter speed of a typical photo taken outside in daylight would be something like 1/500th of a second. Quick, like the blink of an eye. Properly focused, the action is frozen in time and the subject detail is sharp.
When I normally photograph fireworks, I will use combined settings to force the shutter to remain open a "couple" seconds (give or take). Paired with a tripod (and a recommended shutter release remote), the glowing embers flowing across the sky are recorded as string-like steaks.
With this particular image, I add to the recipe a "rack-focus" maneuver. My lens is set to manual focus, targeted at the fireworks. After I pull the trigger to begin the exposure, I gently and smoothly adjust the focus to end with a scene that is out of focus.
The result is a photo of steaks that seem to vary in size from end to end. Or in this particular example, the embers flickered in the sky, giving us the dots and blurry blobs.
This is actually quite simple to execute. The reality is that it takes a fair amount of experimentation to master.