Nigel

I've spent a couple of hours thinking about your post with a slightly furrowed brow and now I think I understand. What you're saying is that a raw file is not only the original image as taken by the camera (which is all I thought it was) but also the parameters of the camera settings which it would have used at that time to effectively create a jpeg image. Therefore when a raw image is opened in Adobe Camera Raw, it will apply the parameters to the raw image upon display of that image. By clicking on 'default' you presumably revert to the raw image as taken. Therefore I now understand why the camera settings can speed up post image processing and I now understand why it can take Adobe a bit of time to add new cameras to their ACR file. Gadzooks, I hope I've got it right..........