Size of a DNG RAW file

[SimonW]

I normally have my Pentax file type set to Pentax RAW, and the size of each file is around 8MB. The camera can be set to save RAW files in Adobe DNG format instead, and thinking this might be a better option I've just tried it out. Taking the same shot in both modes I found that the DNG files are twice the size - about 16MB. Does anyone know why this might be?

[Oly Paul]

Simon I think it might be that its Pentax's own version of the Adobe DNG format (it is after all a open format) , I have always converted to DNG what ever camera I have owned and I have always found that is has been a little smaller than the manafactures raw file.

For example my Olympus E-30 12mp camera has a orig ORF raw size of 11.2 mb but when converted to DNG it is 10.8 mb, but as I usally embed a fullsize jpeg image in the raw file (there are numurous adavantages to this)  this  usally takes it up to 11.7 mb.

I would suggest downloading Adobe's standalone DNG converter from here  http://www.adobe.com/support/downloads/detail.jsp?ftpID=4576   and try converting a few PEF files and see what the size of the resulting DNG files are.

[SimonW]

Thank you for that reply and the link Oly. I downloaded the converter and tried it and can confirm your findings - the DNG created by the Adobe converter is slightly smaller than the PEF original.

In my mind it raises more questions than it answers, and I found another oddity. Elements opens both the DNG file converted from PEF, and the DNG file direct from the camera, in ACR as it should. However, my Paint Shop Pro will open the PEF version correctly (though I don't normally use PSP for the RAW process), but when it opens the DNG file created by my camera, it shows a completely black image. And it will not open the DNG file created by the converter at all. So there must be some fairly major difference between the two DNG formats apart from file size.

I guess the real question is: Given that the Pentax DNG files are so large, is there any loss of data at all when using the Adobe converter software to go from PEF to (the much smaller) DNG?

[Oly Paul]

Thank you for that reply and the link Oly. I downloaded the converter and tried it and can confirm your findings - the DNG created by the Adobe converter is slightly smaller than the PEF original.

In my mind it raises more questions than it answers, and I found another oddity. Elements opens both the DNG file converted from PEF, and the DNG file direct from the camera, in ACR as it should. However, my Paint Shop Pro will open the PEF version correctly (though I don't normally use PSP for the RAW process), but when it opens the DNG file created by my camera, it shows a completely black image. And it will not open the DNG file created by the converter at all. So there must be some fairly major difference between the two DNG formats apart from file size.

I guess the real question is: Given that the Pentax DNG files are so large, is there any loss of data at all when using the Adobe converter software to go from PEF to (the much smaller) DNG?

Adobe Dng is a compressed lossless format just as the PEF format is, but the DNG format that Pentax uses is not compressed.  Olympus used to use a none compressed format and the 5mb E-1 used to give a raw ORF file of 10mb, now it has caught up with the times and the 12mp E-30 now give a 10.2 mp ORF file size...twice as big a image but still nearly the same file size.

The bottom line is that if it is lossless compression no data is lost and you have nothing to worry about except smaller file sizes. 

[spinner]

Thank you for that reply and the link Oly. I downloaded the converter and tried it and can confirm your findings - the DNG created by the Adobe converter is slightly smaller than the PEF original.

In my mind it raises more questions than it answers, and I found another oddity. Elements opens both the DNG file converted from PEF, and the DNG file direct from the camera, in ACR as it should. However, my Paint Shop Pro will open the PEF version correctly (though I don't normally use PSP for the RAW process), but when it opens the DNG file created by my camera, it shows a completely black image. And it will not open the DNG file created by the converter at all. So there must be some fairly major difference between the two DNG formats apart from file size.

I guess the real question is: Given that the Pentax DNG files are so large, is there any loss of data at all when using the Adobe converter software to go from PEF to (the much smaller) DNG?

Maybe I misread something somewhere, but I was under the impression that Adobe was pushing for a universal file format, something like JPG or GIF for converting RAWs because the arguement was maybe, 20 yrs. from now software writers might stop supporting say, my D50 NEFs because the camera had been out of production for decades. So DNG would stand in for your RAW and never be outdated. If that is not case why use it? If it is the case, then I'm surprised PSP wouldn't open them. Maybe there's an update out there for it.

[Oly Paul]

If it is the case, then I'm surprised PSP wouldn't open them. Maybe there's an update out there for it.

PSP is not exactly renowned for supporting or updating its support for Raw file formats!

Even the latest version X2 Ultimate does not support a lot of the latest cameras..but it does support Adobe DNG  .

[anglefire]

I'm not particularly concerned that RAW files will become unsupported in future years by say, Adobe, because you always have the Manufactures program that came with the Camera (Assuming that they do supply one!) - and if not, by the time it happens, just ask some 12 year old kids to knock a converter up for you!