Sony A7SIII vs A7III Video Image Quality
Sony A7SIII, which was released in 2020, quickly became one of the most beloved mirrorless video-centric cameras, but how it stack against the widely popular A7 III? Can you tell the difference just by looking at the images? Does it justify a 2x price tag? And can one be used as a B camera for another?
We decided to answer these questions by doing a series of tests that evaluate camera picture quality and show their strengths and weaknesses.
WHAT WE DIDN’T TEST
We didn’t test low light performance or rolling shutter. Both cameras have great low-light performance, and using ISO up to 6400 should not be a problem on both cameras.
In terms of rolling shutter performance, A7SIII’s fast readout times make the rolling shutter almost unnoticeable, and it’s on the same level as bigger cinema cameras. A7III on the other hand has below-average rolling shutter performance, which should be noted when filming fast-moving objects or handheld.
COLOR REPRODUCTION
A7III was a huge improvement for Sony in terms of color quality compared to previous models but when comparing it against A7SIII they look very similar. Skin tones look almost the same with the biggest difference being that A7S III's white balance is leaning toward green and A7III is more purple. You can see the difference between the background paper and between her sweater.
Next up, log images using the custom LUTs, we can see that the difference now is less obvious, with A7III being slightly more green. The difference can be easily corrected but we decided not to do that in order to show the difference between the color response using the same white balance values.
Moving to a more challenging scenario we used window light as our key and tungsten light for a fill. We set both cameras to daylight white balance preset and used Slog2 and Slog3 gammas. Judging by the result of normalized images we can see that A7SIII is definitely better in terms of color reproduction and color separation and A7III shows some magenta color in the shadow areas which makes the image look less pleasing to the eye.
DETAIL AND SHARPNESS
Here’s where A7III takes a slight edge over A7SIII. It uses a 6K sensor for downsampling the image with results in more detail and higher sharpness. You can easily see it when zooming in on the images.
Having said that, we wouldn’t call the image from A7SIII soft. We had A7SIII footage playing on a 65-inch OLED TV screen and it looked stunning.
Codecs
That’s the biggest issue with Sony cameras that we had in the past. While Sony has provided log profiles that are used in their professional cinema cameras, the high compression and low bitrate made using those profiles pretty much unusable. That’s why many people were using Cine or HLG profiles instead of Slog3, which has the best dynamic range and gives you a lot of control over your image during post-production. With the Sony A7SIII, the issue has been eliminated, and now we have access to the 10bit 4:2:2 high bitrate codec, which is capable of handling the most challenging shots in Slog3.
In our first test, we decided to compare the images using the default profile (No PP) on both cameras. The test card is lit by a daylight fixture on the left and a tungsten fixture on the right. When looking at the images straight out of cameras they look almost identical with a slight difference in white balance and sharpness.
But once we apply an extreme grade to both images, the differences become noticeble.
You can see that the image from A7SIII holds up fine while the footage from A7III suffers from banding and purple fringing on the left side of the card.
When we switch both cameras to log profiles the difference is even more stark.
We can now see the image breaking apart a bit on the Sony A7SIII while A7 III looks pretty bad.
Again, both examples are extreme to demonstrate a point, and in real life, you don’t need to push the images this far. When using a neutral image profile the cameras look almost identical, but when switching to Slog the codec limitations of A7 III become more apparent and might become an issue when normalizing the footage.
Conclusion
Based on our tests, A7III is still a good camera and can be easily used as a backup for A7SIII, FX3, or Sony cinema cameras. The biggest issue with this camera is the lack of a decent codec to work in log profiles, which should be remedied in the upcoming Sony A7IV.