Dear Sony

The mirrorless camera market has matured quite a bit over the last couple of years. And at such a fast pace that today's mirrorless cameras are a valid alternative to the DSLR for certain types of photography. The A7 cameras are one of the greatest mirrorless cameras on the market today. These cameras have a lovely fullframe Sony EXMOR sensor inside of them.

One of the greatest advantages of the latest Sony EXMOR sensors is the dynamic range they offer. Thanks to this photographers can decide to expose for the highlights (so they won't get blown out) and recover the shadows afterwards (while post-processing the images) or underexpose the whole picture by a couple of stops at base/low ISO (e.g. to keep noise levels low) and lift the exposure afterwards.

On paper this all sounds as good as it gets, however there is one (big) problem. Due to the fact that lossy compression (which basically means that data is thrown away from the RAW file in order to keep the file size down) is applied to the RAW files in all of the A7 cameras (and possibly other Sony cameras too), artifacts start to show up. These artifacts are visible in certain parts of the image when lifting the exposure/shadows by a couple of stops, but sometimes even show up when hardly any image processing was done.

1) A quote from an article on the RawDigger website:

"All that is necessary for the artifacts to threaten the quality of the final image is a combination of high local contrast and a flat featureless background."

2) A quote from a forum post by Fred Miranda on the Fred Miranda forums:

"I was able to replicate a situation where the compression is visible. When shooting a high contrast subject where the shadows are very close to pure black. When trying to recover the shadows, artifacts become very apparent."

One might ask if this issue is caused by the lossy compression that is applied to the Sony RAW files. Let's compare an ISO100 Sony A7 II RAW file to an ISO100 Nikon D750 RAW file (which both use a very similar Sony EXMOR 24.3MP fullframe sensor). This can easily be done by downloading the RAW files from the "New studio scene comparison tool" on the DPReview website.

You can find a quick comparison I've made, right here:

Sony A7 II RAW vs Nikon D750 RAW

As you can see, the artifacts are not there in the Nikon D750 RAW file which is merely 6,5 MB bigger in file size (24 MB for the Sony A7 II RAW file vs 30,5 MB for the Nikon D750 RAW file). Because of this, it's (very) sad to see that Sony is crippling the performance of their sensors in the A7 cameras by applying lossy compression to the RAW files.

We, photographers, would like to ask that current (e.g. the A7 series, via a firmware upgrade) and future camera models have an option to store uncompressed/lossless compression RAW files in addition to the currently available lossy compression RAW and JPG storage options – in much the same way as earlier generations of Sony Alpha cameras offered RAW and cRAW options. Preferably lossless compression since it takes up less space than uncompressed while maintaining the same image quality.

Best regards

A disappointed Sony enthusiast