Thanks to Matthew Tippett, I've got a *ist-DS RAW file to play with. The first think I noticed is that this one (a simple test case) is only 9MB in size. Pentax have implemented a compressed format for raw images - the PackBits scheme required by baseline TIFF.
While I wouldn't expect more general images to compress as well as the test image, it's still nice to see something smaller than 12MB. Other things I've noticed: There are a few more changes in RAW file format than I would expect. While most of these are in the (Pentax private) Maker Note data, there are enough other changes to make it doubtful that all software which currently supports *ist-D raw files would work with ones from the *ist-DS. One piece of software that definitely doesn't work is the Pentax Photo Browser supplied with the *ist-D :-( It looks as though some of the superfluous metadata from the RAW files is no longer copied into converted JPEG files. This may be the case, or it may be that the production software/firmware behaves differently from the pre-production version used to create the test image I have. While some of the data may not be copied, I'm not seeing the amount of size reduction I would expect in the Maker Note data.
