The important thing to remember here is that you want to make your color correction on your log footage while it’s still in log and not after it has been converted into Rec709 (or any other color space). So often, the first thing you will do is convert your footage from log into Rec709, to be able to properly evaluate it, however your color correction should almost always take place before that log conversion, therfore making it effectively the first step you are making.įor example, if you’re grading in Davinci Resolve, log conversion would happen on a node which takes place after the node on which we will do our color correction. However, sometimes it’s hard to evaluate the log footage prior to converting it into a monitor referred space such as Rec709. Often, you will hear that color correcting is the very first step you should take. So we’re talking about relative neutral starting point.
We definitely don’t want to neutralise any creative decisions taken during the shooting process, so if, for example, we have a scene heavily lit by tungsten lights with white balance set to 4300K or even 5600K, that would usually mean this was the intended mood of the scene and a creative decision. Now bear in mind we’re not talking about making an absolutely neutral footage. Otherwise we can’t be consistent in our color decisions. This makes much sense as we always want to start from a neutral point.
This is the process of balancing the exposure, contrast and white balance of the footage so we’re starting from a neutral point. Usually the very first step we would want to do is balance our footage or color correct it as it’s often referred to. So how can we solve this issue? First let’s take a look at the process of color grading to better understand the steps we would typically do to color grade our footage. I’m not saying you can’t achieve great results, you definitely can, but it’s harder. A simple exposure adjustment in S-Log2 usually requires a separate treatment of shadows, midtones, highlights and often contrast as well. Specifically you’ll find out that the shadows in S-Log2 just as highlights are more compressed and that they need separate treatment. So what does this practically mean? It means that when you are working with S-Log2 footage, most of your color grading controls like lift, gamma, gain, offset, contrast and many others do not really work as they were intended to work. I would really recommend you read this excellent blog post by Alister Chapman which covers pretty much all of the differences between S-Log2 and S-Log3 formats. Arri’s Log-C for example, just as Sony’s S-Log3 are both based on the Cineon curve characteristics. However, most color grading tools are really designed to work optimally with Cineon log curve, developed long time ago to allow digitising of film in 10 bit data. In theory this was a smart move by Sony as it would make it easier to match S-Log2 footage to other Sony cameras. While S-Log2 is an excellent container, it was designed to work with 14 stops of dynamic range and was optimised to match the characteristics of video sensors. It was paired with Sony’s S-Gamut which was specifically designed to encompass all of the colors that can possibly be created by Sony F65 sensor. You see S-Log2 was actually developed to be used in Sony’s F65 camera. To understand why S-Log2 footage is harder to grade we need to go back a bit. “How can I make my S-Log2 footage easier to grade?” And it’s a good question indeed as it’s harder to grade S-Log2 footage than it is to grade S-Log3 or other log formats? But why? This is probably one of the more common questions we get asked.
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