yes and no. once you install CHDK to the card , it should load automatically. What CHDK gives you is basically an expanded menu for accessing functions of the camera. So once you have the CHDK installed push the alt key to access the new menus. From there you can do TONS of things that you couldn't before, like turn on RAW saving feature, RAW on only first shot, turn of dark frame subtraction, display a battery life indicator, ambient or chip temperature, display histograms real time, etc, etc , etc. It is actually a little beyond may capabilities, but I am having fun learning. You can also add extra "scripts" that let you do things like fast motion detect. (great for lightning photos). All of the info you need is on the Wiki, or linked to it, although it can take some time to find it. FYI the CHDK works with MANY canons not just the S5is. If you have any more questions let me know, I'll see if I can help.