One question that comes up quite frequently is which camera functions affect RAW images and which affect JPEG images on the EOS 50D.
C.Fn II-1 Long Exposure Noise Reduction – Both RAW and JPEG
C.Fn II-2 High ISO Speed Noise Reduction – JPEG Only
C.Fn II-3 Highlight Tone Priority – Both RAW and JPEG
C.Fn II-4 Auto Lighting Optimizer – JPEG Only (Unless Using DPP for RAW)