Sony NEX-7 and the use of legacy ultra wide lenses

In a previous article I wrote about the possibility of attaching nearly every interchangable lens to the NEX camera system via an appropriate adapter. And I already told you how you can configure your NEX so that it’s easier to work with your legacy lenses.

But there is still a problem when you use ultra wide lenses originally designed for the Leica-M camera system. Depending on the lens you get a strong coloured cast in the corners of your image. Meanwhile this problem is well described throughout the web. For example in an article of Luminous Landscape, the blog of Steve Huff or the blog of Jim Kasson.

My own experiences confirm these observations. Depending on the lens (and of course your subject) you get a strong coloured cast which you can’t ignore. The following example shows an image which was taken with the NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6. At the stage of post-processing I didn’t apply any correction for any of the known lens defects (like chromatic aberration or distortion) nor did I correct for coloured corners or vignetting.

Uncorrected example image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.
Uncorrected example image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.

But at the cost of additional post-processing there is a solution available which is based on the free software cornerfix (which is available for Mac and PC). At the stage of post-processing I didn’t apply any correction for any of the known lens defects (like chromatic aberration or distortion) but I did correct the coloured corners and vignetting with cornerfix.

With cornerfix corrected example image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.
With cornerfix corrected example image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.

Before I corrected the corners I generated my own lens-correction-profiles. Therefore I followed these instructions. For the flat field reference file I took a picture through a matted glass panel.

Flat field reference image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.
Flat field reference image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.

After that I followed the instructions for correcting images with cornerfix. I’m very pleased with the results and at the cost of some additional post-processing I get perfectly usable files from my legacy ultra wide lenses on my NEX-7. In the following example I corrected the coloured corners and vignetting with cornerfix and I corrected the lens defects (chromatic aberration, distortion) within Adobe camera raw. Some digital shifting, a crop to 3:4 and adding again some vignette completed the modifications of this image.

Image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.
Image taken with NEX-7 and the Voigtländer Ultra Wide Heliar 12mm/5.6.

For the additional post-processing with cornerfix you need files in the DNG format. And to convert the Sony ARW files from the NEX-7 to DNG you will need at minimum the version 6.6 of the Adobe DNG converter. As my workflow was already based on the DNG format the additional post-processing is not much of an issue 🙂

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