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Data loss using DNG converter by Adobe


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Currently, my LR5.7 does not support Sony A7II and A7RII RAW files. When I used the DNG converter to convert such files into .DNG, it was successful, but I noted the file size had been reduced by half. Does any Member have such experience and is data of the RAW lost in this process?

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IIRC the a7R-ii has a user choice between compressed or

uncompressed Sony Raw. Which are you using ? I'm only

speculating, but maybe if you're shooting compressed, but

then opening those in Sony's software they "unpack" and

so appear as "full size", but the Adobe does NOT unpack

them so in Adobe they appear as only half the size you'd

see using Sony software ? 

 

Just guessing .... A little knowledge CAN be a dangerous

thing [but it can also help with "thinking ouside the box"].

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Not all compression is created equal... digital cameras use simple versions of compression algorithms due to the low power and high throughput constraints the operate under. That's true of both lossless and lossy compression techniques.

 

DNG's lossless compression is based on the ZIP algorithm, which does better than most cameras can do internally. I suspect the difference you're seeing is the incremental improvement ZIP can make compared to Sony's internal quick and dirty approach.

 

Note the DNG also supports lossy compression, do check to make sure you don't have that option selected in whatever you're using to convert.

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  • 4 weeks later...

As I understand, DNG uses lossless zip compression by default, and the Sony files are completely uncompressed. As a test, try compressing one of the Sony RAW files into a .zip and see how the size of that file compares to the DNG, if they're within a small margin of each other that would probably explain it.

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