I just posted a blog entry on an issue with Ligthroom 2.5, Camera Raw 5.5 and DNG Converter 5.5 that affects Mac PowerPC customers. Please read the entry here: http://blogs.adobe.com/lightroomjournal/2009/09/important_note_regardi ng_light.html
Unfortunately, the comments on the Lightroom Journal blog do not seem to be functioning so please comment in this thread.
Lightroom, Camera Raw, DNG Product Manager
While preparing this update, you might also look into the problem of printing through Lightroom on the Epson R800. Printing through PS CS3 works fine but Lightroom produces darker tones even after having followed all the tips on the various forums.
I have experienced exactly these symptoms on images from Olympus E500 and E520 Cameras, and cured it by reverting the software as you say, However, I am not using a MAC, but a very average PC running WindowsXP SP3, so I don't think the problem is just confined to MACs.
Customers converting their proprietary raw formats from Sony, Olympus, Panasonic and various medium format digital cameras should also not use the DNG Converter 5.5 with the compatibility setting lower than "Camera Raw 5.4 and later."
Is this going to permanently damage the RAW data?
If yes, how come? If the problem is in the demosaicing, the future version (5.6?) should bring the DNG's back to live. I thought, converting to DNG only copies the raw data to a new "container" (ok, maybe some lossless compression), but does not alter the raw data in any way.
In some cases using the older compatibility option will force the creation of a linear DNG, which is demosaiced. Hence the bug in the demosaic method will effectively be baked into the image data.
For mosaic DNGs there is no issue.
In some cases using the older compatibility option will force the creation of a linear DNG, which is demosaiced.
This didn't come to mind, because I wasn't aware there were other cases of forced conversion to linear, apart from several recent Panasonics, for which the manufacturer wanted forced behind-the-scene lens correction.