Sony SLOG to Colour Space Transform and ACES

There's been a long running argument in the Sony Fs7 community, regarding which flavour of Slog is the 'best'. I'm ashamed to say I've been a part of these arguments on a few occassions, and for my part I've always championed the use of Slog3, S-Gamut3.Cine.

There are several reasons for this. When I first got the camera, there was talk that the new S-Gamut3.Cine colour space was superior. It didn't have that Sony 'look'. It was closer to an Alexa etc etc. One DOP I know bought the camera based entirely on this colour space!

When I'd had the camera a while, I realised that my main reason for shooting Slog3.Cine was the ease of passing over footage for post. Most Fs7 users were using it, so it became a standard - further compounded by the large amount of LUT's made for this specific Colour Space. So I was quite happy to stay there and never go into the menu to change over to one of these guys:

 Why bother???

Why bother???

Recently however I was put onto something interesting in Da Vinci Resolve. A DOP mate of mine Anthony Brown told me about Colour Space Transform (CST). I'm going to link to Anthony's video on how to do this at the bottom of the blog. With this technique you can essentially take any camera profile and convert it to something else. Slog2 to Slog3 for example. Or Slog3 to Arri CLog.

Note on the video: Everything exposed at base 2000EI ISO. Noise reduction OFF. Exposed using grey card and false colour, as well as light meter. Slog3 and Slog2 were actually at the exact same T-Stop, despite having different middle grey points. This is good to know if you use a light meter. They're the same! Also... To all those guys out there who keep telling everyone that you MUST overexpose Slog - or you get hideous noise. Where's the noise in these images? :)

I find this test interesting for several reasons. One is about bringing cameras to a standard in post. I recently shot a feature doc mainly on Fs7, but we do have a bit of footage shot on an Fs5 (Slog2) and some VLog stuff. The editor in this case is using ACES to standardise everything. ACES is great! But many find the workflow a little daunting. I'm not a grader, so I can totally understand the reservations of taking your project to ACES. For many of us, we love our LUTs! CST seems like a great, and easy, way to bring everything to that standard place.

There's also the potential advantage of using a much larger colour space on your Fs7. S-Gamut and S-Gamut3 are huge compared to S-Gamut3.Cine. Slog3.Cine was always sold to me as being 'user friendly'. A colour space that was easier to grade etc. When using CST or ACES, this just doesn't make sense. Why not use the larger colour spaces? Slog3.Cine will no doubt remain the 'standard', but I for one will be looking at shooting future projects that might require a heavier grade in S-Gamut3.

Lastly. I think this method just looks better. Like many of us, I've been using the Bert LUT on just about everything. But I've had issues with it. Sometimes it does weird things to skin, or it makes everything a bit green. I think it has a definite 'look', which I'm not always crazy about. It's still a great way to quickly wrangle your Fs7 footage into a much nicer place - slap it on, job done! But for me personally, I think CST to Arri or ACES gives a much more neutral image with better colours all round.

Here's all the stills, so you can compare for yourself. I did notice that Slog2 to Arri and ACES is ever so slightly different to Slog3. Look at the green in the plants on the left. Still a completely acceptable match though!

 

Anthony Brown's CST tutorial: