Last year, I published a comprehensive guide to exposing and grading S-Log2 with the Sony a7S. In that video, I introduced the wolfcrow system. In over a year of use, thousands of video professionals have used the wolfcrow system to shoot and produce great images with S-Log2. In this article, I wanted to expand on the wolfcrow system with a practical example for the new cameras Sony has launched – the a7R II and a7S II.
Before we get into the new video, please watch the original video first. I introduce the concepts behind the wolfcrow system and I won’t be revisiting them again in the new video. The new video assumes you have watched the first video. Here’s the original guide to exposing S-Log2:
Link to detailed article with notes and explanations: How to expose and grade S-Log2 on the Sony a7S
The wolfcrow system in a nutshell
- Custom white balance your camera in Movie mode – luckily, the new a7S II won’t let you white balance in log modes, and it will result in errors if you try.
- Default settings for S-Log2, S-Gamut color space and detail level -7.
- Keep everything important (that will be noticeable later on a big screen) above 40 IRE. This is the most important bit.
- In order to do this, you might have to overexpose by 2 to 3 stops. The exact number is irrelevant, as long as you follow the above point.
- The important thing is to keep your exposure constant. For every scene, the amount of overexposure should be constant.
- For the a7R II, use Zebra 70 to figure out the exposure zone for skin tones. If this is too high, you can use the same zebra, but reduce exposure until the Zebra vanishes. This will give you the region between 55-60 IRE. Cool, right?
- For the a7S II, use custom Zebras for 40 IRE cut-off, 107 IRE highlight cut-off, and 50-70 for skin-tone (depending on everything else).
- It is easier to do this with an external monitor that has a waveform. A false color tool can also help to a certain extent. Even so, you can use just the Zebras on the camera to expose correctly.
Here’s a chart that will help you visualize it correctly (click to enlarge):
A practical demonstration of the wolfcrow system
I’ve put together the following video where I demonstrate the different exposure levels and study them in Adobe Premiere Pro. It will show you a common scenario where you have to light a face and have a key and fill side with a lighting ratio of 1.5:1 (I measure lighting ratio in stops because that is more practical for me).
- At one point I say lighting/contrast ratio is 2 stops, but it’s only 1.5 stops. However, that’s with a light meter. In the actual scopes, the difference is a full 2 stops because you can isolate the darkest and brightest portions. You can’t do that with a light meter.
- Ignore the color tint for this video. I shot with the a7S, though the newer cameras have gotten rid of the green color cast in S-Log2. I’ve tested each camera separately, and I have additional videos in my guide for each of them. There is no difference between them as far as exposure for S-Log2 is concerned.
- Shot at 3840×2160 Prores LT on an Atomos Shogun at 25 fps. White balanced to 2900K
If you’re not seeing any difference between 2 stops over and 3 stops over, here’s an image for you to study (red channel only, graded with raised levels in PS, click to enlarge):
- 3 stops over is definitely cleaner in the shadow side (look at the ear). It might seem like we’re splitting hairs, but –
- Study the background. The background upper portion is 1 stop under key, and the lower portion is 2 stops under key. The noise is clearly and visibly greater at 2 stops over. This is the problem – you get okay results on the main subject, but if you have anything darker it will suffer. That’s why 3 stops over is better.
Lastly, if you’re worried about highlight clipping when overexposing, you can go low, just be willing to live with the consequences. Guess what? I did not make these cameras. I can only help in getting the best out of them!