Proper preparation prevents piss poor performance!

[soulman]

...I would exopect that you'll see no difference at all apart from a significanly smaller file size when compressed...

From what I understand, most if not all RAW files are already compressed. I just zipped a 38.4MB RAW (Canon CR2) and the ZIP saved only 900K. Another test on a 41.4MB file saved 1.1MB, so we're looking at around 2-2.5% which could be useful but isn't a big deal. On the other hand, a 126MB uncompressed TIFF ends up as 41.5MB, so I think we can be pretty confident that the RAW files are compressed already. And yes, there is no degradation in image quality - ZIP and all the other archive formats are lossless.

[JM Tran]

From what I understand, most if not all RAW files are already compressed. I just zipped a 38.4MB RAW (Canon CR2) and the ZIP saved only 900K. Another test on a 41.4MB file saved 1.1MB, so we're looking at around 2-2.5% which could be useful but isn't a big deal. On the other hand, a 126MB uncompressed TIFF ends up as 41.5MB, so I think we can be pretty confident that the RAW files are compressed already. And yes, there is no degradation in image quality - ZIP and all the other archive formats are lossless.

good point mate

another way to make your files smaller is to convert the native raw file ie. Canon CR2 to Adobe's DNG raw format

[Dan Gamble]

From what I understand, most if not all RAW files are already compressed. I just zipped a 38.4MB RAW (Canon CR2) and the ZIP saved only 900K. Another test on a 41.4MB file saved 1.1MB, so we're looking at around 2-2.5% which could be useful but isn't a big deal. On the other hand, a 126MB uncompressed TIFF ends up as 41.5MB, so I think we can be pretty confident that the RAW files are compressed already. And yes, there is no degradation in image quality - ZIP and all the other archive formats are lossless.

Wasn't aware of that. I thought the nature of RAW was that is was a completely uncompressed and unprocessed format. Thanks for the info.

[soulman]

I thought the nature of RAW was that is was a completely uncompressed and unprocessed format.

Yeah, I thought so too until I started exporting files from Lightroom to Ps for processing - which means they have to get converted to TIFF or PSD - and found that they were all 3 times the size of the RAW. This is not all due to the compression, but it's the main reason for the difference in size.