The Sony F3 is a lightweight professional HD camera with a sophisticated Super 35 mm CMOS sensor and PL mount. The image quality is quite impressive using the standard REC709 gamma curve at a said eight-stop dynamic range, though on a scope with a chart it produces a few more. The in-camera Picture Profile options allow for manipulation to RGB, contrast and saturation, as well as the Gamma selections CINE1 to CINE4. Although the camera does very well in low light, the sensor is actually capable of seeing more.
Wanting more dynamic range and colour depth out of the camera, I sought S-Log. I called John Deboer at Sim Video, and he had an upgraded F3 brought in from Vistek for some tinkering. The S-Log upgrade happens to the camera system’s firmware and costs over $3,500. Note: Some rental houses have yet to upgrade F3 bodies to do S-Log, so be sure to ask about S-Log capabilities and costs if this is a format you wish to shoot in.
This upgrade allows the camera to record in what is called a Log. As John Banovich csc talked about in an interview in the January issue of Canadian Cinematographer (see John Banovich csc tells The Honest Truth, January 2012), Log is short for Logarithmic, and allows for more information to be recorded. The expansion of image information from REC709 to S-Log is about eight times. S-Log, or Log, is not RAW, though it is an 800% increase of dynamic range, which allows for capture of everything the sensor can really see.
Let’s try to better understand Log and REC709 for a moment. The standard curve in most digital cameras is called REC709. It is a measure for consistency of picture from start to finish. It represents the contrast and colour that the eye generally sees. However, it doesn’t necessarily show everything the camera’s sensor is capable of. REC709 offers a suitable and nice-looking image for most broadcast shows, mostly in factual/reality using a fast-paced workflow for final output on web or TV. Though if looking to the big screen, where the image is stretched out, or to major networks who have higher broadcast standards, then it would make sense to seek more dynamic range, faster mb/s speed and greater colour depth out of the camera. Enter Log.
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Photo by Sarah Moffat
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S (Sony)-Log was specifically designed for the F3 sensor. The first major benefit to shooting S-Log is an increase in dynamic range, up to 13.5 stops, from what I could see. The camera no longer has to compress the image into an .MPG2 onto SxS cards at a maximum speed of 35mb. Now in 4:4:4, from the DUAL LINK stream, out to a 10-bit record deck of choice, usually best set to Apple ProRes, it can write to a speed of 100mb/s. The gamma curve becomes almost flat, in a way providing more dynamic range and allowing for much more control in post over the colour “look” desired. Also the jump from 8-bit to 10-bit may sound small, but it is four times more colour information. Hence S-Log truly does provide a lot more.
Here's a trick for those using a recording device with perhaps one HD SDI in, and willing to sacrifice a little image to save a few rental dollars, or time and money in post: you can pull a 422 S-Log image out of the “Monitor SDI Out” BNC on the back of the camera. That output was intended to be for a director/DP monitor, however you can cheat it! I did, and it worked well, out to a Mini-KiPro. But be aware: while in S-Log you have access to an LUT (lookup table) menu for that Monitor Out. There are many LUTs you can choose from in the menu, and if you hook up the camera to a monitor and flip through the LUTs, you can actually see the image colours change on screen, as each LUT has its own gamma curve. Though if you shoot with an LUT selection on, that is the look you will record. Yes you can still manipulate the image in post somewhat, though not as much with all LUTs off, and in S-Log only. When you turn the LUT off, the image on the monitor becomes sort of dull-looking, that is the “Log.” It is absorbing far more light information than most monitors can comprehend, as they are also standardized to REC709. To get around this look on the monitor, you can convince the director and others that it's going to look great by dialling up the colour and contrast knobs on the monitor. Sort of "faking it," and also so you don't hear, "Why does the picture look all washed out?” for the whole day!
I discovered this in my own test so far and also talked with Dylan Macloed csc, who has been shooting a ballet story with the National Ballet of Canada. He has been using two F3s and shooting in S-Log. “We did shoot S-Log. We monitored REC709. I had the editor apply a slight curve to our dailies. But by shooting S-Log we were able to capture as much information in camera as possible and preserve it for the final transfer," he says.
I have been testing the F3 in S-Log for an upcoming narrative and am looking forward to working with a greater dynamic range and more colour depth. Giving me more than what the camera has already provided, without the upgrade, is going to be so exciting to see in post!
Sarah Moffat’s camera experience includes motion picture and still photography. She has worked in drama, documentary and live broadcast.
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