In most situations, Arsenal's long exposure blending will enable you to capture long exposures without using a neutral density (ND) filter. However, there are some situations where you may still need an ND filter.
For example: if you're creating a long exposure during the middle of a bright day, you would normally require a 10-stop ND filter. Using Arsenal's long exposure blending, the shot could have visual artifacts if there is a lot of movement in the scene between shots (e.g. fast-moving clouds). This is caused by the scene changing during the time between exposures. In extremely bright situations, a neutral density filter may still be necessary.
To minimize the potential of artifacts with long exposure blending, we recommend stopping down your aperture to f/8 or smaller. This will result in longer shutter speeds for the individual shots, requiring Arsenal to blend fewer exposures. This will reduce the gaps during which scene motion can occur, minimizing the chance of blending artifacts.