What are the advantages and disadvantages?
I've converted everything to dng lately as I don't intend to switch away from LR/ACR, it's just too good - and multiple other apps start supporting dng.
Advantages of dng:
* metadata information inside the file, no xmp sidecar
* faster rendering vs. cr2 (if you "embed fast load data")
* you can update the jpeg preview to the post-processing state
* saves 20% disk space right away (if you drop the full res thumbnail that's in the cr2)
* lossy & downsized options while retaining dr and lossless wb adjustment
* some post-processing software doesn't support it, namely dpp & dxo
* xmp sidecar of cr2 gets written faster than the whole dng when updating metadata
However, the option to convert cr2 to raw won't go away, if you're not sure you can do it anytime in the future, even with the free Adobe DNG converter.They are always adding stuff to the DNG converters so converting them now could restrict what future developments would be possible later one. IE: Lens correction tech.
I don't understand that - you can just update an older dng version to the new one.
Unless you're using lossy dng, the "converter" just *wraps* the raw data from the cr2 into a new dng container and adds a new thumbnail and fast load data (if you request it). Absolutely no file information is lost on cr2->dng, you could even write an app to convert it back.
I checked my older 7D files that I sampled in .DNG two years ago(experimenting at the time) and they were lossy compressed. Your right, and I tested a new file w/o lossy compression and I cannot see a difference between the .cr2 and the .DNG.
But I can't help but cringe knowing that the file is smaller somehow and that the converter has to move data around from the original sensor data in the .Cr2. Then again, if we're talking long term, .DNG wasn't really accepted fully by the top camera manufacturers and has no better chance of lasting 20+ years than a .NEF or .CR2. Its still not a ISO standard yet and if I had to choose between the two Multi-national billion dollar companies like Adobe or Canon, I'd chose Canon way before Adobe. The way Adobe has been using their software as leverage to me means that the yet adopted ISO standard .DNG is not free and clear from their control. If anything, its giving more control to adobe because to get the best performance, adobe software will be the best, thus sell more product, and if you have all your catalog in .dng, have fun trying to move to another software workflow. In a way, it could turn into an AdobeRaw format per say.
Another note that some photo competitions require the original raw and a converted .dng could be brought into question. Even though not very likely to occur but another reason to stray away from .dng
Long term means trust, and Nikon/Canon has been around alot longer than Adobe.(which still makes the best .dng converter around)