The LRGB+HA workflow uses either 4 or 5 filters
- Luminance (optional)
Adding a hydrogen-alpha filter into the mix allows for certain images (especially galaxies) to show more of the hydrogen-dominated regions.
For luminance, this workflow will work with either a synthetic luminance or a real luminance. A real luminance is preferred if you are able to image at a location with low light pollution or through a light pollution suppressing filter as these will allow for longer exposures, which means more signal and detail. If this filter is not available, simply use a synthetic luminance.