By Matt Allard
Like me you probably hadn’t heard of Sony S-log or even had the faintest idea about what it is or what it does.
S-log was originally only available on super high end Cine cameras like the Sony F35. Now that it’s available for theI 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 from a technical perspective. I’m just going to explain what it does to an image in the real world. I have researched by reading various articles and I’ve tried to not make this article too technical. I am also happy to be corrected on anything I have gotten wrong.
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 recorded on 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. I’ve shot comparisons between S-log/non S-log, graded S-log/ungraded S-log and graded non S-log/graded S-log. There are also comparisons between a Canonusing the Technicolor Cinestyle profile and the F3 with and without S-log.
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. This usually means losing all the detail in the shadows. S-log helps you to keep some of that information you would normally lose.
The human eye can see around a 14 stop range of light but it works in the reverse way of a camera 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 – it can’t easily recognize the gradual steps in bright scenes like your eye can.
Straight from a camera’s 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 16 bit 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 10 bit 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.
The conventional way to combat the bright skies would be with a ND grad filter in front of the lens, but I found when usingthese filters dont tend to look as good as on say my Sony PMW-350 XDCAM. With the F3 you can see a noticeable graininess where my filters are graduated and I imagine that unless you are using the highest possible quality filters you will still be able to see the change in quality. S-log benefits you greatly by allowing you to do without filters in some cases because it handles the highlights so much better.
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. It can be recorded straight to SxS cards but this not the best way to use it as S-log benefits in the color correction process from recording to a much higher bitrate codec and broader color space. When shooting S-log you can only choose either 5600k or 3200k and you can only shoot in progressive and not interlaced (I couldn’t find an explanation as to why).
Are there any negatives to S-log? From my experiences so far you don’t need to use it for everything and it’s not a quick fix miracle that will magically make all your material look wonderful. It does add increased noise to the image so you have to be careful when using it.
The positives? It is fantastic when you have to shoot scenes that has a high level of contrast. I have been able to shoot a lot of high contrast scenes I would never even 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 with a fast lens.
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 as it really does take your F3 and put it on steroids.
About Matthew Allard, Aljazeera Senior Field Cameraman, Kuala Lumpur:
Matt has been a Camera/Editor in TV news for more 20 years, previously working for both Channel 9 and Channel 10 in Australia. Twice Network Ten Australia’s cameraman of the year as well as being a Walkley Finalist for outstanding camerawork in 2006 (for coverage of the Cronulla Race Riots) and a Logie Finalist for outstanding news coverage 2006 (Bali 9). He is a multiple ACS (Australian Cinematographers Society) award winner. His Sword Maker story that was shot on a won the prestigious Neil Davis International News Golden Tripod at the 2011 ACS Awards. He has covered news events in more than 35 countries, from major sporting events to terrorist bombings. Based out of the Kuala Lumpur broadcast centre in Malaysia he is an avid user and follower of new technology, shooting stories on HD broadcast cameras, the Sony F3 as well as new Canon DSLRs.
You can follow him on Twitter @mattaljazeera