Since this picture is a long exposure of a boat rowing in the water, why does the boat not show in the picture but the lights on the paddles do? Is it because the boat is darker so it is averaged out with the water that remains when it moves on but the lights are really bright so they are more dominant than the background?
Pinbat
Your intuition is close! Dark objects moving at fast speeds tend to "disappear" since the light they reflect only adds a little bit to what is recorded at each pixel they cross, compared to the background which dominates most of a pixel's recording time. A bright light however will be recorded because it adds a lot to what is recorded at a pixel.
killawhale2
Is it okay to think long exposure photos as integration of high exposure photos over time? I think that fundamentally they are equal but I might be missing some things.
moridin22
Integration over time captures what's going on here pretty well! It's not necessarily high exposure though, since you probably want the end result to look like a normal-exposure photo with whatever additional effects you are adding.
michaeltu1
It seems as though the lights on the paddles are bright enough to have its light reflected by the water. If this is the case, shouldn't the lights also be bright enough to light up the boat/paddles, making those objects bright as well?
michaeltu1
After considering this for a few minutes, the reason why the paddles don't show up/aren't lit up while the reflection of the light on the water is shown is probably in part due to the different BRDF reflection functions of the paddles vs water.
xiaoyankang
Here're some amazing long-exposure photographs, and it also explains how to achieve such effects. https://create.adobe.com/2013/10/1/long_exposure_photography_of_toby_harriman.html
Since this picture is a long exposure of a boat rowing in the water, why does the boat not show in the picture but the lights on the paddles do? Is it because the boat is darker so it is averaged out with the water that remains when it moves on but the lights are really bright so they are more dominant than the background?
Your intuition is close! Dark objects moving at fast speeds tend to "disappear" since the light they reflect only adds a little bit to what is recorded at each pixel they cross, compared to the background which dominates most of a pixel's recording time. A bright light however will be recorded because it adds a lot to what is recorded at a pixel.
Is it okay to think long exposure photos as integration of high exposure photos over time? I think that fundamentally they are equal but I might be missing some things.
Integration over time captures what's going on here pretty well! It's not necessarily high exposure though, since you probably want the end result to look like a normal-exposure photo with whatever additional effects you are adding.
It seems as though the lights on the paddles are bright enough to have its light reflected by the water. If this is the case, shouldn't the lights also be bright enough to light up the boat/paddles, making those objects bright as well?
After considering this for a few minutes, the reason why the paddles don't show up/aren't lit up while the reflection of the light on the water is shown is probably in part due to the different BRDF reflection functions of the paddles vs water.
Here're some amazing long-exposure photographs, and it also explains how to achieve such effects. https://create.adobe.com/2013/10/1/long_exposure_photography_of_toby_harriman.html