DNG v RAW Poll

[lawrence]

I have been assessing the merits of converting my RAW files to DNG and would be interested knowing the practises of other RFF members.

 

[willie_901]

If you convert to DNG, there is no reason to delete the original raw.

I save my raws on a separate external HD (which is backed up) and consider this to be my virtual file cabinet of negatives.

A 1 TB HD costs about as much as an OEM camera battery or a high-performance SD HC card costs. This is not an extraordinary expense.

 

[bobbyrab]

Is there an advantage to converting? Quite often to save space and processing time I shoot medium raw files from a Canon 5d iii , I tried converting these to dng and the file size increased.

 

[lawrence]

Is there an advantage to converting? Quite often to save space and processing time I shoot medium raw files from a Canon 5d iii , I tried converting these to dng and the file size increased.

Normally there is a decrease in size when you convert to DNG using the default settings in the Adobe Digital Negative Converter software but I think this may depend on the options ('Preferences') you select E.g. The size of the JPEG preview and whether you embed fast load data.

 

[shawn]

I haven't done this in the past but will be selectively doing this as part of the Photo merge options in LR6. That will take multiple RAW files and either HDR merge them or blend multiple shots to a panorama and save the resulting file as a DNG.

Shawn

 

[dotur]

I always shoot RAW, post process and export to JPG in LR, and then delete the original files. Duplicates of the final JPG version(s) are stored on several hard discs and on Flickr.
I used to convert RAW files to DNG but don't bother any more.

 

[majid]

I didn't use to bother with DNG (apart from my Leicas in which case RAW==DNG), but I recently bought a Sony RX1RII with grossly inefficient RAW that can get 50% lossless compression, zip-style, from DNG, and am toying with the idea of converting to DNG in Lightroom, archiving the RAW files to offline hard drives, and keeping only the DNG in my online catalog. I would consider the same if I had one of the Nikon cameras with lossy compressed NEF.

 

[bobbyrab]

So the advantage is all about file sizes then?

 

[lawrence]

So the advantage is all about file sizes then?

Not at all. More important is the incorporation of data that otherwise has to be written to an XMP sidecar file as well as format standardisation. A full description of DNG is given here.

 

[jarski]

Also that all edits can be stored into DNG itself, no sidecar file.

 

[shawn]

Also that all edits can be stored into DNG itself, no sidecar file.

Will this allow different editors to write to their info to the same file? That would be very handy for when I edit certain RAW files outside of LR.

Shawn

 

[View Range]

Some of the earliest raw formats are no longer supported by raw converters. In theory raw converters will stop supporting Canon and Nikon raw formats before they stop supporting dng. That would be many years away.

I'm always confused about the concern over file size. RAM is expensive but is still far larger than the file sizes, in any computer used for photo purposes; storage memory is dirt cheap, ignoring SSDs. jpeg is a poor format for editing since you lose the all-important metadata and critical bit depth.

 

[jarski]

Will this allow different editors to write to their info to the same file? That would be very handy for when I edit certain RAW files outside of LR.

Shawn

I know it works across Adobe family. Write changes with LR, and Bridge & Camera Raw (step before Photoshop) will show them as expected. And vice versa, but you probably have to read metadata again from file, if it was in LR catalog already.

Can't comment on other raw editors, can they save changes to DNG as well.

Am fan of this feature of DNG, as it saves time if I ever return to old photo and need new jpeg from it. No need to edit again.

 

[raid]

I didn't use to bother with DNG (apart from my Leicas in which case RAW==DNG), but I recently bought a Sony RX1RII with grossly inefficient RAW that can get 50% lossless compression, zip-style, from DNG, and am toying with the idea of converting to DNG in Lightroom, archiving the RAW files to offline hard drives, and keeping only the DNG in my online catalog. I would consider the same if I had one of the Nikon cameras with lossy compressed NEF.

Thanks for clarifying this point. I see only DNG in my M8/M9 and no RAW. The Olympus E-P2 and E-PL1 have RAW but no DNG.

If the images are poorly composed or exposed, is there really a need for these?

 

[charjohncarter]

I use a camera that produces DNG, I then convert these DNG files to TIFF using MakeTIFF. Then with very little post processing convert the MakeTIFF TIFF file to a visual file with PerfectRAW. Works very well, especially if I'm careful shoot so I have a 'good' histogram.

 

[willie_901]

Is there an advantage to converting? Quite often to save space and processing time I shoot medium raw files from a Canon 5d iii , I tried converting these to dng and the file size increased.

It's possible you inadvertently selected a conversion option that includes the original raw file in the DNG file.

There is a completely different conversion option that invokes lossless compression during DNG conversion. In this case the files will be approximately 15% smaller. And no data is destroyed during the conversion.

In 2012 Adobe included a lossy compression mode for DNG conversions. This is a space saving compromise that is somewhere between a highly compressed JPEG and the lossless DNG in terms of how much data is irreversibly lost during compression.

To make matter more confusing, some Adobe products offer the option to store large amounts of metadata with the individual DNG files as well as within the rendering software's data base. When this option is invoked, the DNG file size increases.

 

[willie_901]

...

If the images are poorly composed or exposed, is there really a need for these?

Yes.

Because there is no way to be completely certain the image is poorly composed or exposed before you view it. There is no remedy for poor composition or severe overexposure. Often underexposed images can be rescued by increasing the global rendering brightness in post production. In this case the result will always be superior for a raw file compared to a JPEG file since the raw contains all the available information you recorded.

I believe the M9 offers both a lossy compression and lossless compression options for in-camera DNG files. If I remember correctly lossless M9 DNG compression is not linear. Instead it compresses data for highlight regions more than shadow regions. Since highlight regions contain more photon noise, many photographers conclude Leica's lossy DNG compression is harmless. Other brands use similar schemes.

The M9 has a DNG + raw option. DNG and JPEG are not mutually exclusive. If storage space is an issue, deleting unneeded DNG (and JPEGs) is trivial.

 

[majid]

Thanks for clarifying this point. I see only DNG in my M8/M9 and no RAW. The Olympus E-P2 and E-PL1 have RAW but no DNG.

RAW is just a generic name for a data format that (in theory) stores data exactly as read from the sensor without any processing applied to it. DNG is Adobe's attempt to make a standardized RAW format, but they released it as an open standard.

Leica made the laudable decision to use a standard format (DNG) instead of a proprietary RAW format. As did Pentax IIRC. No one else followed: Canon has CRW, Nikon has NEF, Sony has ARW, Fuji has RAF and Sigma has X3F.

If the images are poorly composed or exposed, is there really a need for these?

Modern sensors have better dynamic range and color gradations than the JPEG format itself, usually 12 to 14 bits vs 8, and you can usually salvage one or two stops' overexposure from RAW compared to JPEG. Also, if you correct for white balance or change the tone curve, you don't suffer from the rounding errors introduced by a coarse format like JPEG. It's like the difference in range between a negative and a print. The workflow is slightly more complex (although software like Lightroom makes it nearly effortless), but if you don't shoot RAW, it's as if you threw away your negatives once you made a print, i.e. it's like shooting Polaroid.

 

[majid]

So the advantage is all about file sizes then?

When each frame is 85MB and you store everything on SSD because spinning rust hard drives are too unbearably slow, that's nothing to sneeze at.

DNG is also more future-proof than proprietary formats.

 

[ColSebastianMoran]

The big issue is the possibility that the software of tomorrow won't be able to read the files we create today in anything but the most important filetypes.

I see DNG as an Adobe creation, more exposed the whims and business currents that drive Adobe. I want images to be available to my grandkids, say 40 years from now. Will Adobe be around 40 years from now?

I'm keeping my .NEF files. I use Lightroom, but I export the sidecar files, because I'm not counting on my Lightroom catalog being usable forever, more likely something will open the .NEF with the sidecar. I make good jpegs of every image and for special images a TIFF as greater insurance of future usability.

I'm betting someone will keep producing software that opens .NEF files.

Will future software be able to open DNGs? PSDs? Lightroom catalog? The iPhoto catalog? I'm not counting on any of these.

I'll bet on NEF, but I hedge by keeping good jpeg and/or TIFF.