As a Roblox developer, it is currently impossible to create a depth of field type of effect.
Right now, the blur effect is limited to a gaussian blur which doesn’t offer much creativity when it comes to adding blur into the lighting.
Depth of Field would essentially blur objects “out of focus” of the camera whilst objects in focus would not be blurred. I feel this would make lighting effects so much more dynamic.
I have seen this effect being showcased in a 2015 video which demonstrates a number of different lighting effects however it hasn’t been implemented, even after 4 years:
DOF would be awesome, but I feel like roblox is gonna drag their heels on it since they want mobile to be on par with PC and so they’ll limit the PC games to the capabilities of the mobile games. Unfortunately mobile devices just don’t have the capabilities of a full on computer. Though some of the more recent mobile devices might be good enough to implement something like this, the vast majority of players on roblox are using an older generation that cannot support this reliably, and something tells me roblox isn’t going to release it on some platforms only.