July 20, 2010

Learning, Travel Photography

Hey Gang,

As you know, Juan and I are here to help and listen. Well, recently, we received an email from one of our loyal podcast listeners, Gene McCullagh, who disagreed with both of us on the DNG format – the format to which I converted my RAW files while teaching a workshop a few years ago in Papua New Guinea (as illustrated by the above screen grab) .

We listened to Gene, and thought you’d like to hear what he had to say. Here goes.

• • •

Dear Rick & Juan,

Thanks for a great podcast!

I just finished listening to the most recent one where you answered a question about converting raw to DNG. I usually agree with you but you both got this one dead wrong.

“It’s a waste of space” – fact is that nearly ALL DNG files are smaller than the raw files they came from. There’s no need to keep both the raw and the DNG so in fact – NOT converting is a waste of space.

“It’s a waste of time” – sure, if you do it on import. But why not let your computer work while you are asleep? Lightroom will easily convert thousands of raw file while you sleep. Just set it off and go to bed. Now you are getting a lot done!

“You don’t get any benefit” – Aside from the space savings and the assurance that your files can be read in the future, you no longer need to keep track of XMP sidecar files. DNG allows all of that to be written into the file. This prevents a great many headaches.

“If you shoot Canon or Nikon or…” – you may not be worried about reading a Canon raw file in 30 years but who knows? Even Canon has changed its proprietary raw format several times. DNG is safer in this regard.

Keep up the great work guys! I get a lot from your show and really enjoy it.

I just couldn’t let this one go though! ;-)

Gene McCullagh

• • •

Gene, your email inspired me to dig out some of my PNG DNG files. Here are a few favorites.

Before moving to the next image, here’s a joke: Two cannibals in Papua New Guinea are sitting around a fire eating a clown. One cannibal stops eating, turns to his friend and says, “Does this taste funny?”

Here’s a shot of me (before I went back to the lodge to convert all my RAW files to the DNG format) and two Huli Wigmen clan member. These dudes are super friendly – even to clowns!

Explore the Light,


This post was written by:

- who has written 171 posts on The Digital Photo Experience.

Canon Explorer of Light Rick Sammon has published 36 books, including Exploring the Light and Digital Photography Secrets.

When asked about his photo specialty, Rick says, “My specialty is not specializing.”

You can follow Rick on twitter at http://twitter.com/RickSammon and visit his website at http://www.ricksammon.com

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5 Responses to “DNG on DPE & PNG”

  1. Milton Anglin Says:

    After I download from my CF card I convert to DNG. I keep the raw files on one HD and the DNG files on another. That is my “belt and suspenders” approach to backup.


  2. Jef ar Floc'h Says:

    I have the ever-so-slight advantage that I can save as DNG in camera.
    +1 for Pentax !


  3. Jon Westcott Says:

    Hi all,

    Came to write same as Gene! for me having lightroom info written right into the file is huge. Just remember to turn on write changes to XMP in Lightroom settings (if you are using DNG then this will write there and not XMP). Combined with the space saving of around 30% and for me it’s a no brainer!

    Thanks for the great podcasts guys!


  4. Matt Vanecek Says:

    Rick & Juan,
    Just listened to the DPE podcast on my way home, and came to froth and blather about the DNG answer (not really–I was genuinely confused why y’all would say something like that about the size).

    To be fair, if you embed the original RAW inside the DNG (which can be done), then yes, you’d get half again to 2/3 more space used. But just the DNG alone is 1/2 to 2/3 the size of the original RAW–mine are typically 11 to 12MB, vs 18 to 21MB for the CR2 files out of the 50D. You do lose the Dust Delete and Focus Point data, if you actually use those. I don’t…

    Now, if you’re doing forensic or legal photography, where the integrity of the original must be scientifically provable, I’m not sure how DNG holds up there–because the XMP data is actually written into the file itself (another HUGE HUGE benefit, in my opinion! but I don’t know how that affects the legal integrity of the file. But I don’t do legal photography, so don’t care).

    Personally, I convert everything to DNG on import. Get home, pop the card in, start the import, and go unload. Sure, it takes a little longer, but it’ll save my some $$ on disk space! And if you dump to a hard drive in the field, and then import & convert when you get back home or to the hotel, then convert is that much quicker, as you’re not bringing the data over the slow USB interface.

    Anyhow, whatever works for a person is what that person should do. However, last I heard, Scott Bourne does DNG (or probably, his assistant!!) :)

    It was a good podcast. I keep meaning to send in some questions that have been bugging me (and aren’t answered on Google…).



  5. Juan Pons Says:


    Thanks for the thoughtful and great comment. I’ll let Rick speak for himself, but I personally COULD NOT bring myself to deleting the original RAW files as they come out of the camera, so if I converted to DNG, that would be an additional file and hence the comment about using so much space.

    I suspect that this is also Ricks thinking…



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