NIKON NEF files do not contain true raw data. by Christian Buil

I was researching star photography and discovered that apparently Nikon cameras — specifically the D3 and the D300 DO NOT produce a true RAW file. As a lifetime Nikon user this is disturbing to say the least.

Christian Buil offers fasinating information about Astronomy, star photography, and CCDs.

"In the astrophotography world most photographers recognize this fact and mainly use Canon. For regular day photographer this isn't much of an issue. Nikon produces wonderful images. But a close study of the night images shows that Nikon's "RAW" is being processed by the camera software."

This is very technical stuff but very interesting.

-Keith Skelton



PHOTO AT LEFT- A CR2 file from a Canon 40D (30 sec. exposure). Some hot pixels are visible. They are left intact by the firmware. The noise structure has approximately a gaussian shape. The RAW file is the direct representation of the sensor output signal. Accurate measurements and processing are possible.

PHOTO AT RIGHT -A NEF file from a Nikon D3. The image is a 30s exposure in dark at 400ISO with all the identified noise reduction set to OFF. The image shows an obvious artificial structure, which indicates that a digital filtering by the firmware has been applied once the image is taken. Note the considerable texture difference with a short exposure. The purpose of this internal filtering is clearly to smooth the thermal signal (hot pixels) and thermal noise. RAW files from Nikon D3 for long exposures (probably superior to one second) are definitively not a RAW file!