Note that there are a couple of workarounds to achieve the same ends. The way to get a RAW file is to use Canon’s multiple exposure feature and set the exposure control method to Average – that lets you take up to 9 exposures to combine (which would give better NR than the 4 exposures of MSNR). Another is to simply take multiple, successive exposures and combine them in Photoshop (overlay them and adjust the opacity to equally weight them (i.e. opacity = 100/image number, so the bottom image is 100% opacity, the second is 50% opacity, the 3rd is 33%, 4th is 25%, etc.).