1. It says: “Because Adobe’s de-mosaic recipe has already been added/embedded with the RAW”. Not true, (unless a specific non-default option has been requested). By default, (whether or not the original raw file is embedded), the DNG file contains the original sensor data, ready for any raw converter to process as it chooses.

2. A reply says: “But hardware independence is a BAD THING(tm)…. It will handle almost any image from any digital camera nearly identically. DNG is an attempt to treat all images almost identically”. Most certainly not true! For example, if the D50 and D70s had a different colour response, the calibration tables in the DNG file be different. A DNG file contains the original sensor data, plus lots more information which identify the specific characteristics of the camera concerned, for example colour response, anti-aliasing amount, sensor configurations, and many others. Where cameras need to be treated differently by the raw converter, the DNG file is intended to hold the detailes that the raw converter needs to do so.

3. The same reply actually added: “The anti-aliasing bayer microlenses placed in front of the sensor and the exposure system are different between those two cameras. Nikon Capture 4 knows this and treats them with a slightly different recipe when processing”. So what? DNG doesn’t lose anything, it adds metadata! A raw converter can either use the camera name such as “D50″ or D70s” to make its decisions, if it knows about the camera, or use the “anti-alias strength” if it doesn’t know about the camera. More, not less, choice.

A DNG file contains a superset of the contents of a NEF, even when the original isn’t embedded.

@Gordon: DNG is future-proofed and hardware-independent. It is also a very simple specification to implement (it’s just TIFF spec with a standardized metadata format). It is because these advantages that it is useful. Imagine if your camera comes from a vendor that might go out of business, or Canon decides to stop supporting your old digital camera, or your image editing tool is made by someone really lazy.

But hardware independence is a BAD THING(tm). An NEF converted into a DNG has the unique camera data as a string (like “Nikon D50″) in the header field. For all intents and purposes, that file is identical to the Nikon D70s NEF converted to a DNG, other than that string. Applications that process and handle DNGs will handle images from both cameras identically. It will handle images from different lenses identically. It will handle almost any image from any digital camera nearly identically. DNG is an attempt to treat all images almost identically.

(There are some arbitrary parameters in the DNG spec such as “anti-alias filter strength” that can make a difference in processing, but these are qualitative numbers, not quantitative and thus aren’t camera-specific, aren’t accurate, and aren’t precise.)

The problem is cameras aren’t identical.

The Nikon D50 and Nikon D70s RAWs are not the same and shouldn’t be treated as such. The anti-aliasing bayer microlenses placed in front of the sensor and the exposure system are different between those two cameras. Nikon Capture 4 knows this and treats them with a slightly different recipe when processing. DxO Optics Pro does the same and even adjusting for lens defects and lens-body combinations.

You need the NEF file to take advantage of either program. Can you reconstruct the NEF file from a DNG file? No.

Sure, replacing your RAW files with DNGs is a view that is shared. It is shared among people who think that a RAW file format is no different than a TIFF with metadata who “rave” about how “great” Adobe Camera Raw is.

Among those of us who know better, doing so is just buying into some Adobe marketing bullshit.

DNGs are future-proofed and hardware-independent and that is a great thing. They are not your digital negatives and should not be treated as such.