One thing that's starting to happen is that some raw converter makers are starting to drop support for older cameras. In particular, the old Kodak and Fujifilm DSLRs seem to be the primary targets. But I've also noticed that the Nikon D1x is losing the old 10mp (line doubling) support from a few converters these days, too. Even with new cameras we sometimes see lack of raw support: the recent Fujifilm X-Trans sensor cameras aren't always supported by all raw converters, and many of the conversions that are available are sub-standard.
The problem is simple: raw files are all proprietary. Well, not quite all. There are a couple of companies using the DNG format, which is openly published by Adobe. Pentax and Leica are the notable DNG users at the moment, and both are low volume vendors, which is one of the reasons why the Kodak and Fujifilm is getting dropped: software developers can't afford to test and support low volume products indefinitely.
So what can you do if you have a non-mainstream camera whose raw support is waning? Three things, basically:
- Get a copy of dcraw and make sure you maintain a computer that can compile and run it. A lot of raw converters used this openly available demosaic engine as the basis for their own converter, and this source code supports a lot of those early cameras whose support is being dropped.
- Get DNGed. Elsewhere on this site I have an article about DNG. Generally, I'm not a fan of DNG as it just adds to workflow (and potentially storage space). But if you truly fear loss of support for raw images you have from older cameras, converting them to DNG is one possible solution to your problem. I say "possible" because if the original raw format isn't Bayer and requires something special in the demosaic, converters that "support DNG" may or may not be able to deal with this.
- Perform a conversion to 16-bit TIFF while you still can. Your goal in this conversion isn't to create the best possible final image, but to preserve as much information as possible. Thus, you want to make sure you don't blow highlights, don't drop below black levels, and keep the overall conversion as high in the 16-bit container as possible (to minimize rounding errors). You want such conversions to be color and contrast neutral, if possible, as taking out such changes is far harder than adding them in later. I'd argue that you should avoid noise reduction and sharpening, but if you want to do noise reduction, do so carefully and as minimally as you can tolerate.
One final point: I strongly prefer always keeping originals. Thus, if you use the DNG or TIFF route I suggest that you keep the original raw file intact and in your archived files: your DNG or TIFF should be a copy, but not your only copy. Who knows what comes next in software processing? Some day there may be someone tinkering with files of the type you thought lost as a hobby, and I have no doubt that future knowledge will make for potentially better demosaics. So don't just convert and delete those originals.