CCC Forum

Sony produces some amazing digital sensors, but when it implements them in its own cameras it uses lossy compression when writing Raw* files. In others words, some of the information captured by the sensor is discarded when the Raw file is written to the memory card. This is in contrast to most other manufacturers who record all the data from the sensor in their Raw files. Does Sony's use of lossy compression matter? According to this article on DPReview, the algorithm which Sony uses to decide what to ignore is inelegant and can adversely affect the image in certain circumstances, although for many people it might rarely be an issue. It does seem odd, though, that Sony has decided to limit its cameras' capabilities in this way.

http://www.dpreview.com/articles/283406 ... ompression

* JPEGs are unaffected for the simple reason that the original purpose of the format was to create smaller file sizes which it achieves by employing lossy compression.

This isn't something new, they've been doing it for a while now and it was really noticeable when I used the A7II. Annoyingly, shot-ruiningly so in many cases. Weirdly they don't do it for Nikon?

For me it reeks of compromise, a technical trade-off so they could achieve something else. What that is (or even if true) I don't know, nor even if it's still needed. My suspicion is they will do away with it in the third generation of A7 cameras.

Even despite this, they are still by far the most exciting mirrorless player in the market

davidc wrote:Weirdly they don't do it for Nikon?

Sony only supplies the sensor and Nikon is responsible for determining how the data is processed. The question is more why does Sony need to implement compression when Nikon doesn't? Although the manufacturers all give their processing engines different names, the reality is that there are only a small number of firms which produce the chips, making Sony's decision all the more mystifying. It certainly detracts from what is otherwise an innovative range of cameras. Perhaps they do not want to give themselves too much of an advantage over the rest of the market?

davidc wrote:...... it was really noticeable when I used the A7II.

My suspicion is they will do away with it in the third generation of A7 cameras.

I took a quick look at what Michael Reichmann had to say about it in his review of the A7RII - the relevant bit is under the heading "The 12 / 14 Bit Discussion". He says that it was apparent when pixel peeping, but did not affect the final image. From what the Sony execs he talked to had to say about it, it seems probable that this is a "feature" that will not be present in future cameras.

https://luminous-landscape.com/sony-a7r ... on-report/