Sony a7 III Internal vs External S-Log Recording Differences

The Sony a7III is a fantastic mirrorless camera with excellent internal recording options. Pair it with an external recorder like the Atomos Ninja V and it becomes even more powerful… but not only that.

During testing of the Sony a7III, Gerald Undone noticed some differences between internal and external recording beyond the 4:2:2 tests he was interested in. Have a look at the video to check out his intriguing findings and get more insights on the topic.

Indeed, there seem to be some interesting differences happening when shooting S-Log. The internal and external image have some significant anomalies. The internal recording appears to be flatter, this is confirmed by the scopes, and the internal recording appears to be squeezed into what may be a broadcast legal range.

Adding a plugin in Premiere to extend the footage beyond legal range and the internal and external recordings seem identical and conversely adding a broadcast legaliser to the external footage makes them identical too.

The colours also seem affected, the saturation and accuracy are different internal and external. This would certainly cause issues when matching footage.

SLOG External

S-Log External

There is a clever workaround to avoid the S-Log squeeze – start recording in Cine and then switch to S-Log. You will have to assign a custom button to achieve this as you can’t enter the menus while recording but that’s easy enough. Still a nuisance but a good trick.

Slog Internal

S-Log Internal

It seems that only the S-Log profile is affected and the other gamma settings are fine, so it must be the S-Log settings that are ‘wrong’.

Grading the squeezed image introduces some unwanted colour artifacts and it is challenging to achieve a match so shooting in S-Log internally might not be the best idea.

Slog Full Image

S-Log Full Image

Overall, Gerald’s testing seems to be quite comprehensive so I would tend to believe his results. It really is quite curious. Is the S-Log gamma squeezing to make the most of the cameras internal bit depth? Or is it just a bug? Let us know what are your thoughts in the comments below.

[source: Gerald Undone]

Order Links:

Sony Alpha a7 III Mirrorless Digital Camera (B&H, Amazon)

Atomos Ninja V 5″ 4K HDMI Recording Monitor (B&H, Amazon)

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