You need a RAW file reader. I have one that is probably the most popular. It is a free download from Adobe and works on Mac or PC (you have to indicate which one you want to download). The DNG converter needs constant updates to accommodate new cameras being released on the market. Just GOOGLE this term. "Adobe Free DNG converter," and find what you need from there. When you have the free DNG converter your computer will be able to convert your DNG files from the SD card to RAW files.
Of course after you download it and try it out, if you don't like it, just go the program file in your downloads and delete it.