In this lesson we’ll quickly compare S-Log2 between the a7R II and a7S II.
Notes on test:
- All shots were custom white balanced. 3000K on the a7R II and 2900K on the a7S II (Measured under Standard Creative Style).
- The middle grey patch on the chart was exposed to 0.0, +1.0 and -1.0 for these tests.
- Footage was shot at 4K 100 Mbps XAVC-S in full frame mode.
- A one-stop (0.3) ND filter was used with the a7S II to even out exposures. The native ISO for the a7R II is 800 and a7S II is 1600.
- The ND filter will cause a slight shift in color balance, but this is something to be expected in the real world as well. The ideal method is to white balance after you put on the ND filter.
- Shutter speed was constant at 1/50. Aperture was at f/4.5 and sometimes f/6.3 for underexposure. Focus on the chart.
- Lens used: 28-70mm OSS at 50mm.
What are we looking for? Three things:
- Dynamic Range
- Noise
- Artifacts due to compression, posterization, etc.
S-Log2 at normal exposure
Sony a7R II (click to enlarge):
Sony a7S II (click to enlarge):
S-Log2 one stop over
Sony a7R II (click to enlarge):
Sony a7S II (click to enlarge):
S-Log2 one stop under
Sony a7R II (click to enlarge):
Sony a7S II (click to enlarge):
Which camera does S-Log2 better?
Here are things I’ve noticed:
- At normal exposure, the a7S II does better in the shadows (noise-wise), but has slightly more compression artifacts.
- At one stop over, the a7S II does better overall.
- At one stop under, the a7S II is clearly better. The artifacts are bad on both, but we already knew that.
- As far as dynamic range is concerned, they are too close to call. Neither has an advantage.
So which is better? As far as dynamic range, artifacts and noise is concerned, the a7S II is better.
Can we match the two cameras with S-Log2?
Yes, but as in the test, either the a7S II needs a one stop ND filter, or you need to bump up the ISO on the a7R II to 1600.
Which is a better strategy? Bump up the ISO to 1600. As we have seen earlier, this is fine. Adding an ND filter will change the color characteristics somewhat, and we don’t want that.
Once the two cameras are at ISO 1600, then they will be as close as they will ever be. Any minor corrections can be easily applied in the grade.
