Sony a7IV Uncompressed vs. Lossless compression vs. Compressed RAW
For long time I used the uncompressed RAW format with my Sony a7IV to get the best possible quality out of my images. Earlier this year I started to get frustrated with the endless need to add storage space on my PC and NAS, so I decided to give the lossless compression RAW format a shot. After using it for some time now, I feel kind of stupid that I didn’t use it from the beginning.
Here’s a quick comparison between Sony Uncompressed RAW, Lossless compression (L) RAW and Compressed RAW.
I left the Lossless Compression (M) and Lossless Compression (S) RAW formats out of the comparison, because those files are also smaller in megapixels. All the other formats are full 33MP (7032x4688).
All the test images were shot with Sony a7IV @daylight white balance, Sony FE 100-400mm f/4.5-5.6 GM OSS @200mm, f/5.6
The scene was lit with Smallrig RC 30B COB LED Video Light @5500k, 100%
Color target in the scene is the Datacolor Spyder Checkr Photo
Test photos were processed in Darktable. No noise reduction or sharpening was used. The photos with 0EV exposure were only cropped and the photos with -3EV exposure were cropped and pushed +3EV to 0EV. Nothing else was adjusted.
File sizes:
Uncompressed RAW ~67 - 72MB
Lossless Compression RAW ~35 - 46MB
Comressed RAW ~35 - 39MB
There is some variation in file sizes that comes from the amount of details in the image. In general, high ISO images take more space, because of the noise.
Test images
Test scene, exposure set to 0EV with large spot metering
1/100, f/5.6, ISO100, WB daylight
Let’s take a closer look. These are 1500x1500px crops from the test images
Base ISO, correct exposure. (1/100, f/5.6, ISO100, 0EV)
High ISO, correct exposure. (1/3200, F/5.6, ISO3200, 0EV)
Base ISO, underexposed. (1/800, F/5.6, ISO100, -3EV, pushed to 0EV in post)
Second base ISO, underexposed. (1/3200, F/5.6, ISO400, -3EV, pushed to 0EV in post)
Very high ISO, underexposed, no light. (1/40, f/5.6, ISO12800, -3EV, pushed to 0EV in post)
Conclusion
Like Sony says; “Records images with a lossless compression method that causes no deterioration”, seems to be accurate statement of the Lossless compression RAW. I can’t find any differences between Uncompressed RAW and Lossless compression RAW. Even the Compressed RAW, which should have some deterioration of the image, because it’s compressed, seems to be very close, at least in these test images.
I’m not sure what situation in it would be reasonable to use Uncompressed RAW instead of Lossless compression RAW. Maybe some post-processing software can’t handle the Lossless compression RAW? And the same goes with the Compressed RAW, the file sizes are in best case just slightly smaller than the Lossless compression RAW, but we know for the fact, that the Compressed RAW is missing some data. Although the difference is very minor in my test images, (I see a very slight coarseness increase in the noise of the ISO12800 images, Compressed RAW), I see no reason to use anything else than the Lossless compression RAW.
I suggest that you at least give the Lossless compression RAW a try and if your post-processing software supports it, just use it. Uncompressed RAW seems like a waste of space to me.
