Motion blur samples limit too low for a long exposure effect? Im trying to get a long exposure effect using the eevee camera motion blur but the results i get at slower shutter times are very grainy, even at the maximum 64 samples. I tried speeding up the camera animation and setting a faster shutter but i cant seem to get trails of the desired lenght without the grainy effect, and the general render samples dont seem to affect the motion blur samples.

The performance shouldnt be a problem since the objects in the scene are simple emission objects and the current renders are taking about 4 seconds.



How to get a long exposure effect using Eevee?
You could merge multiple renders and or use cycles.

But if the end effect you're going for is just abstract smeared lines, build them using curves and turn up bevel.  On the material, mix a transparent and a emission shader to create a similar effect.  and with eevee change the settings -> blend mode in the material to alpha blend.

This method will give you much more control over the effect too.

As a bonus: use mesh follow -> trace verts option in the Btrace addon to make curve traces from animated objects.
Here's an example I just made.