Is it still considered important to convert raw formats to dng

reader · July 09, 2013, 05:18:45 AM

I'm not in the groove enough in photog trends to know this, but I remember a couple of years ago there was quite a lot of talk about converting raw formats to 'dng'. Back then I remember seeing some good arguments in favor.

Back then my Canon Powershot Pro 1 could shoot raw but it was a little complicated and didn't work in some modes. I rarely used it so only had a handful of canon's raw format. But now with my current A65 I do most of my shooting in raw or raw & jpg, so have collected a few thousand raw format files.

Do I need to convert those I plan to keep to 'dng'? Or I guess what I'm asking is what is the current thinking of old hands here about converting to '.dng'

ianrr · July 09, 2013, 08:10:37 AM

Well for me, the RAW file is the original master ... end of story there.

A converted file is just that, an interpretation by adobe. From my years as an adobe customer, do I trust them? NO!!

For a while I did try it, got sick of keeping the originals as a backup just in case, as meanwhile my file storage started to double.

Adobe could change their policy at the drop of a hat if it suits them regarding the DNG converter, eg "adobe cloud version" rental now the only way of getting any new versions of the software. Seems like a flea brained grab for money to me, sure has pi**** a lot of existing users off is putting it mildly.

Just my 2c worth

Photon · July 09, 2013, 12:16:43 PM

One of my camera does produce directly only DNG and another one only RAW. That is the main reason why I convert all RAW to DNG. I like to avoid too much different formats. I do not assume that DNG will not be supported one day in the future if it does work today. But I experienced that my DNG originating from camera were not supported from CaptureOne for 24 months until release of SW update.

A benefit with DNG is, that you can modify the embedded previews. I do this only once just to reduce the preview size and DNG file size. This because I do not like full size previews in DNG, because with IMatch I am managing anyhow the full resolution exported JPG files separately as versions. My DNGs are write protected because I dislike, that metadata can be modified and prefer XMP sidecars for this. I also dislike, that backup takes long when only some metadata bytes in DNG have changed. But a lot of other users like, that DNG can be modified and then there is no need for sidecar XMP. May be this metadata and backup issue is more relevant for your decision than my minor point with preview and file size.

Regards, Martin

ianrr · July 09, 2013, 12:29:42 PM

two points

every time you modify a file with DNG you end up re-writing the file .. 10-36 meg files on better cameras. each time you re write your image files there is the chance one day of a glitch or power problem that can make them unreadable

If you have lots of files that can take up time as well.

With the sidecar, the original is not ever touched, and a 2k to maybe 40k sidecar file ( .XMP ) is changed or generated. so no rewriting files over again, and to boot you can just copy the .xmp files to a copy you ( maybe should ) have, and the backup has all the adjustments with little data to copy, as opposed to having to re-copy all the dng files .... again.

Hope this helps.

Ferdinand · July 09, 2013, 12:57:15 PM

Disclaimer: I don't use DNG, although I have a few files shot on a borrowed Pentax 645D

My understanding of the attraction of DNG is that older RAW formats may no longer be supported by a given RAW converter, in which case how do you reprocess a file? If you convert to DNG then at least you can reprocess with Adobe s/w. In fact, this is how you would process a RAW image in ACR/PSCS5 now from a new camera that was only supported from ACR/PSCS6.

My understanding is that the problem with DNG is that Adobe keep changing the spec. If you had converted to DNG in the early days and discarded your RAW files (heaven forbid) then you'd be a long way out of date and with no way of catching up. So you've got to keep your RAW files as insurance. In which case, I don't see the value of conversion now unless the Adobe DNG converter also stops supporting older formats.

I think the solution is to keep a collection of the different versions of the DNG converter, rather than converting everything now.

ianrr · July 09, 2013, 01:09:48 PM

QuoteI think the solution is to keep a collection of the different versions of the DNG converter, rather than converting everything now

Good point indeed Ferdinand ...

lenmerkel · July 10, 2013, 02:58:03 AM

Another factor to consider is "How much of the proprietary data in your raw file is lost in Adobe's conversion to DNG, and is that data loss important?".

Part of the DNG specification allows you to essentially include the original raw file inside the DNG, in addition to the converted raw data (incidentally, making the DNG much bigger). The Adobe DNG converter has an option to enable that. Why would you want to do it? Just in case? Isn't the converted DNG a faithful conversion? Probably not 100%.

After all, the whole point of converting a proprietary data format into a "generic" one like DNG is to make it, well, non-proprietary. But at what cost? Are you sure that some really valuable proprietary data didn't get lost or transformed (or conveniently ignored) along the way? I personally wouldn't bet on it.

I actually have more faith in "older" raw formats being still supported by newer versions of software. Developers have enough work on their hands adding support for new raw formats. It actually takes effort to remove support for older formats, so why spend R&D dollars on it, at no benefit? Better to show a continually growing list of supported raw formats on your product's web page.

BTW, I shoot Pentax, and have saved to proprietary PEF, switched to in-camera DNG, then switched back to proprietary PEF again (which I use now in preference to DNG). While the in-camera DNGs don't suffer from the potential loss of data in conversion, I found (as ianrr described so well) that continuously rewriting the DNGs with changes did in fact cause a file corruption. Fortunately (from bitter prior experience) I'm a little obsessive about backups, so could recover very quickly - still a pain to deal with.

Ferdinand · July 10, 2013, 07:56:53 AM

Quote from: lenmerkel on July 10, 2013, 02:58:03 AMI actually have more faith in "older" raw formats being still supported by newer versions of software. Developers have enough work on their hands adding support for new raw formats. It actually takes effort to remove support for older formats, so why spend R&D dollars on it, at no benefit? Better to show a continually growing list of supported raw formats on your product's web page.

There was a converter that dropped support for some older cameras recently. I forget which one that was, perhaps someone else can help me. If a new version of a converter requires you to reprofile cameras, I guess they wonder how far back they really need to go.