Like me you probably hadn't heard of S-log or even had the faintest idea about what it was or what it does.
S-log was originally only available on super high end cameras like the Sony F35. Now that it's available for the F3 I thought I'd do some research and try and explain it in as simple language as possible. Now before I do I'm not some super tekkie guy or an engineer so i'm not even going to try and explain why it does what it does. I'm just going to explain what it does. I'm also happy to be corrected on anything I have gotten wrong. I have researched by reading various articles and i've tried to not make this article too technical.
In a nutshell, S-log is supposed to offer you exceptional tonal reproduction in both the high-lights and low-lights. In other words it can help expose the brightest part of your scene while still keeping the detail in the shadows. We have all shot something when to expose for the brightest part of a scene we have had to stop the camera down which ultimately means losing all the detail in the shadows. S-log helps you to keep some of that information you would normally lose, while also giving you greater range in the highlights.
The human eye can see around 14 stops of light but it works in the reverse way of a cameras sensor. We see only small changes in dark conditions but very big changes in bright ones. With a cameras sensor it sees big changes in dark conditions but only small changes in bright ones. What this means is our eyes see most things that are dark as being dark, but when it comes to things that are bright like say the sky, we can make out very gradual changes in brightness. Thats why a camera struggles when you try and shoot a bright sky while trying to expose the foreground correctly as it cant easily recognize the gradual steps in bright scenes like your eye can.
Straight from a cameras sensor an image appears very dark if it doesn't have a gamma curve added to it. Almost all HD video cameras process video (with a gamma curve) so when it is viewed on your TV it looks correct . This viewing method is referred to as REC709. What REC709 can't do though is display the entire range of what your cameras sensor can capture. The F3 has a 16bit sensor but without S-log you can't capture all that information into a 10 bit signal. Here's where S-log earns its money. It bends the range of the sensor to fit all the information into the allowable 10bit space. It loses some information in this process but it now allows the camera to mimick the changes in brightness that are visable to our eyes. So remember earlier when I talked about why a camera struggles with replicating bright scenes well this is what S-log is helping correct.
S-log does have to be color corrected in post though. A non color corrected S-log image looks washed out, lacks color and contrast. You don't have to record S-log to a 4.4.4 external recorder like a Convergent Designs Gemini or even to a 4.2.2 recorder like a AJA Ki Pro Mini. It can be recorded straight to SxS cards. This is definitely not the best way to do it as S-log benefits in the color correction process from recording to a much higher codec and color space. When shooting S-log you can only choose either 5600k or 3200k and you can only shoot in progressive and not interlaced (could't find an explanation as to why).
The negatives of S-log. From my experiences so far you don't need to use it for everything. It's not a quick fix miracle that will magically make all your material look wonderful. It does ad increased noise to the image so you still have to be careful when using it.
The positives. It is however fantastic when you have to shoot scenes that have a high level of contrast. I have been able to shoot a lot of scenes I would normally never even try to attempt without S-log. It is also quite remarkable in low light. Turning on S-log is like turning on extra lights in a room. It also provides an amazing reproduction of detail that you normally never see. At 18db with the S-log enabled, the F3 can literally see in the dark. My eyes can't see what this camera can.
My over all impression of S-log is "wow!" It is however a $3800US upgrade and is not for everyone. I do however thoroughly recommend it. It really does take your F3 and put it on steroids.
The short video I have made is just some test shots to try and show you what S-log does and looks like. It's not a scientific test, it's just me using the camera. It hasn't been outputted to an external recorder its all been recorded straight onto the internal SxS cards. All comparison shots were done using the exact same lenses and settings unless otherwise noted. There are comparisons between S-log and non S-log, graded S-log and ungraded S-log, graded non S-log and graded S-log as well as comparisons between a 7D using the Cinestyles profile and the F3 with and without S-log.
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