How to properly deal with lens distortion in Sony NEX RAW files?

Question

I have a Sony NEX6 camera and when using the 16-50 kit lens the photos shot in RAW has a lot of distortions. You either have to let the camera correct it using jpeg or you are expected to use Sony's desktop software (called IDC) to correct it. Lightroom also corrects it, but unfortunately aperture does not which is the program I use.

So two separate related problems.

1) If I try to use IDC's correction and then export it back as RAW format. For some odd reason Aperture imports the raw image fine but the image gets a green cast. I can't figure out a way to fix this in Aperture (tried regenerating previews etc)

2) If I use Lightroom's correction and export it back as DNG file, Aperture fails to import the DNG file at all. It's reporting file not supported.

So I'm left with using IDC/Lightroom to correct the distortion and then exporting it as TIFF. But I'm not sure I want to do this because I want to ensure I'm not losing data (the whole point of shooting RAW).

Any help? I'm stuck with images I can't use :(

Answer 1

The big point of raw files is that it is the original unprocessed and unmodified data from the sensor - the minute you do any processing what so ever on the file (for example, distortion correction) it's no longer the unmodified sensor data - even if you export it into a "raw file".

So, exporting to an high bit depth TIFF is just fine, the data loss is minimal (there is some data loss - but that happens because you modified the original data not because you saved to TIFF) - but you have to turn off noise reduction, sharpening, set a flat color curve and in general turn off everything raw processors do to make the image look good.

Or, maybe, if you already have Lightroom anyway (that I guess you have because you plan to use it for distortion corrections) and your camera/lens combination is better supported by Lightroom you should consider switching software.

Answer 2

An exported RAW is not RAW. I have no idea what it is but even if it were encoded exactly the same way, it has lost a ton of information due to the resampling needed to perform distortion correction.

Exporting as TIFF (16 bits or more per-channel) you get the same bit-depth as your original RAW file except that that you have full color information. Depending on how it is done, you may not have lost any information at all except for - again - the resampling needed for distortion correction.

The point is that they lose and keep pretty much the same info. So, go ahead and do the correction in whichever program gives you the best results. If you cannot overcome the green cast, then that leaves just Lightroom.