DNG Files with Legacy Versions of ACR

Question

In our office, we have 16 staff members currently running Photoshop CS. Although these terminals have the newest version of ACR available for CS, which supports DNG files, I ran into a DNG that I was unable to open today. I converted a Raw file from a Fuji S5 Pro using DNG Converter v 4.3.1 without a problem. However when I tried to open it with Photoshop CS, it did not open ACR. Instead I got a "not the right kind of document" error.
I took the same DNG file to a remote terminal that has Photoshop CS3 installed (with updated ACR as of a couple of weeks ago) and had no problem launching the ACR program and opening the file.
We are in the process of replacing all of our terminals at the staff member desks. But this may not happen until the 2nd half of 2008. At that time we will be upgrading all of the terminals to Photoshop CS3. My hope was that the DNG support for the version of ACR we had would be a bandage for working with these files until we were able to complete the upgrade. We can install the software that came with the cameras, but for the sake of consistency in how we file and archive files, since we'll be using DNG in the future it would be nice to now also. I've been able to work with other 'new' Raw files in this manner, but for some reason not the DNG converted from the S5 Pro Raw.
My assumption was that DNG was the same regardless of the initial Raw file type. Is there something I'm overlooking, or are newer DNG files not able to be converted with this legacy version of Photoshop and ACR?

Answer 1

It depends on how you define a raw format. As far as the Camera Raw adjustment controls are concerned, you cannot tell the difference between a linear dng and "raw data" dng, since all the current Camera Raw adjustment controls happen after demosaic step.
(Both Canon and Kodak have cameras that produce demosaiced "raw" file formats in some cases. In Canon's case, the new "sRAW" format is already demosaiced. Some Kodak cameras (e.g. Kodak 14n, etc.) also saved a "lower resolution" raw format that was also demosaiced.)
The dividing line between a "raw" format and a "rendered" format is with whether the data stored in the file is scene referred or output referred. As long as the data is in a scene referred color space, it is easy to change the white balance, exposure, tone curve, etc. Once the data is converted to an output referred color space, it gets much harder to change those parameters without causing artifacts.
That said, it is better to keep the image in mosaic format if possible, since this allows you to take advantage of better demosaic algorithms in the future. For this user, that is not possible because Camera Raw 2.4 does not have a demosaic algorithms that works for the Fuji S5, so using the linear form of dng solves that problem.