DNG conversion question

Just installed lightroom 5.7 on my system and I have a question about converting raw files into DNG. First is, will I lose some details on the photo after conversion? Second is, is it true that DNG files are smaller compared to raw?

I have tried one photo sample and I can't see any difference especially on the file size. Hope you can make some inputs here guys. Thanks.

DNGs are for all practical purposes raw. Leica M uses DNG as their raw format.

DNG has exactly the same RAW data as the original, with some metadata perhaps lost - but not the main stuff. It also describes the raw format so it should be able to be read for many years, unlike CR2 or NEF files.

DNG can be a little smaller. There are new options to resample the DNG down which can make them much smaller than the original - I use this a lot for 36MP files.

Which one is better, DNG or CR2 and how can I make DNG files smaller? Im really new to lightroom.

To dng or not to dng

I'm not sure there's any good reason for converting to DNG unless your camera isn't supported by LR or ACR.

For archival purposes, you'll want to keep the original RAW files. As someone else mentioned already, there is some loss of metadata when converting to DNG -- not a lot, but why sacrifice any at all? If you come back to these files in 10 years and find that the current software doesn't support CR2, you can always perform the DNG conversion at that time. But if you create DNGs now and delete your CR2s, you're never getting the CR2s back. Conversion only works one way: CR2 -> DNG.

Also, Canon software will not support DNG files, if you ever want to use it.

Ok, sorry for the confusion. Let's say I'll import my cr2 files from my memory card to lightroom via converting them into a dng file. What I want is to make the dng file smaller in size (but retaining them as dng). If it's possible, will the images be as detailed as the cr2?

You can embed the CR2 into a DNG, but then you have very large files. I like DNG, and convert all the camera formats I use into DNG to have a common format.

brettjrob, I see. So getting another hard drive would be my best option isn't it? I currently have 1TB for my storage and it's way down to 200gb of free space. I'm running out of space.

brettjrob wrote in post #17319752
I'm not sure there's any good reason for converting to DNG unless your camera isn't supported by LR or ACR.

For archival purposes, you'll want to keep the original RAW files. As someone else mentioned already, there is some loss of metadata when converting to DNG -- not a lot, but why sacrifice any at all? If you come back to these files in 10 years and find that the current software doesn't support CR2, you can always perform the DNG conversion at that time. But if you create DNGs now and delete your CR2s, you're never getting the CR2s back. Conversion only works one way: CR2 -> DNG.

It's possible the DNG converter will drop old camera profiles eventually - you have to download them every time you update the DNG converter. To me having a copy in DNG is insurance. My backup system is something like:
- I keep a random collection on my PC, plus of course working files.
- I keep the original RAW on a disk in my home office, plus a jpeg copy
- I keep DNG on a disk at my friends house, plus a jpeg copy. Updated after every significant event.
- I keep another DNG copy at another friends house. Updated every 6 months.
- I have another disk at a neighbours which backs up my internal disks which I can run as often as I like
- I have cloud backups for small files, and if I really want to I can upload RAW files to either a cloud backup provider or a private area of my website.

tim wrote in post #17319813
It's possible the DNG converter will drop old camera profiles eventually - you have to download them every time you update the DNG converter. To me having a copy in DNG is insurance. My backup system is something like:
- I keep a random collection on my PC, plus of course working files.
- I keep the original RAW on a disk in my home office, plus a jpeg copy
- I keep DNG on a disk at my friends house, plus a jpeg copy. Updated after every significant event.
- I keep another DNG copy at another friends house. Updated every 6 months.
- I have another disk at a neighbours which backs up my internal disks which I can run as often as I like
- I have cloud backups for small files, and if I really want to I can upload RAW files to either a cloud backup provider or a private area of my website.

That's quite a load of work for backing up files.

Jiggo0109 wrote in post #17319815
That's quite a load of work for backing up files.

I have backup scripts, and it's a good excuse to visit friends. Other than the 2 minute drive and a visit with my friends it takes me maybe 2 minutes to connect the drive and start each backup. I'd say in wedding season I do spend about 30 minutes a week on backups, but that's fine with me as they're irreplaceable. Outside wedding season it's about 30 minutes per month.

tim wrote in post #17319819
I have backup scripts, and it's a good excuse to visit friends.

My wife will definitely favor in just buying a couple of hard drives than me getting out of her sight... hahaha
Yes, I love my wife.

Raw files (like CR2) use lossless compression. How much compression depends on the camera make and model. Raw files also have an embedded jpeg. That jpeg might be a small version on older cameras, but most newer cameras embed a full sized jpeg.

When you convert to DNG, the compression might be more, might be less, but is usually not significant (less than 1-2 mb). When you convert to DNG you have the option to embedd NO jpeg. That will save 2 to 5 mb. So a 25mb raw might become a 21mb DNG just by losing the jpeg.

You also have the option of using "lossy" DNG conversion. That will save a lot of space. A lossy DNG can be 40% to 70% smaller than a normal DNG or Raw file. I don't recommned lossy DNG because disk is cheap, so it's better to buy disk. But if you are really tight on disk space and don't want to expand, lossy DNG is a good alternative.

You probably won't be able to see any visual difference between a smaller lossy DNG and a full sized lossless DNG. But the difference is there and can be measured. It's about the same as the difference between a lossless DNG and a jpeg saved at Photoshop quality 10. Lossless and Lossy DNGs are both still "raw" data, so the full detail is still available for re-processing.

Redcrown wrote in post #17319877
Raw files (like CR2) use lossless compression. How much compression depends on the camera make and model. Raw files also have an embedded jpeg. That jpeg might be a small version on older cameras, but most newer cameras embed a full sized jpeg.

When you convert to DNG, the compression might be more, might be less, but is usually not significant (less than 1-2 mb). When you convert to DNG you have the option to embedd NO jpeg. That will save 2 to 5 mb. So a 25mb raw might become a 21mb DNG just by losing the jpeg.

You also have the option of using "lossy" DNG conversion. That will save a lot of space. A lossy DNG can be 40% to 70% smaller than a normal DNG or Raw file. I don't recommned lossy DNG because disk is cheap, so it's better to buy disk. But if you are really tight on disk space and don't want to expand, lossy DNG is a good alternative.

You probably won't be able to see any visual difference between a smaller lossy DNG and a full sized lossless DNG. But the difference is there and can be measured. It's about the same as the difference between a lossless DNG and a jpeg saved at Photoshop quality 10. Lossless and Lossy DNGs are both still "raw" data, so the full detail is still available for re-processing.

Ok, I think you guys just answered my questions. Definitely will purchase another hard drive for my files. I still have another question about shooting in raw but I think I just have to make another thread for that or perhaps link me to a thread about it. It's about camera's settings in shooting raw (Picture styles' sharpness and contrast). If it affects PP if I set sharpness to 6 or 7?