jaysdesk: At first I found it curious that the size of the raw file for the SLT-A77 remains absolutely constant across the ISO range. Then I reasoned that this should be the expected result for unprocessed raw files.
This is not what we observe with other cameras( including SLT-A55, and DSLR-A900, which display some slight variation in the raw file size for different ISO settings).This suggests to me that this time around, Adobe truly, leaves the noise alone, at null settings, in the ACR 6.5(something that I understand was not the case in earlier versions).
The ballooning size of the JPG files at higher ISOs seems to indicate that a lot of noise is passed on to the JPG pipeline.
If there is any validity to any of this, then a meaningful comparison can be made,only if all the raw files for all the cameras, are processed through ACR 6.5.
That interesting.Because actually, canons cr2 uses lossless jpeg compression. So file size vary by several MB depending on scene, iso, bokeh.So I wonder if or what kind of compression sony uses.