No ... flat, log, and RAW are very different things.
Starting with the least of the three ... "flat" ... that means setting the camera's user controls for typically lower than "standard" amounts of contrast and saturation so that you can be sure that all the data the camera's processor can record to disc is recorded. It prevents losing a few bits especially in the highlights and heavily saturated areas, but ... it will get maybe at most a half a stop of wider dynamic range (total difference between black & white points) than at "standard" settings. Given most "economy" cameras need all the dynamic range they can get, it's often worth doing, but still ... just gets a wee bit more. And needs to be done carefully or you lose data from doing it.
What you are doing to a certain extent is recording less data per pixel (relatively) to get a slightly wider range of pixels light-to-dark recorded. This is especially why dropping saturation past a certain point ... just means you no longer have the chroma data to work with. Some cameras (like my GH5) can easily go over-legal on Red saturation. Setting the overall saturation down to a point that doesn't happen helps my post-processing. BUT ... the next step down in the user-settings for saturation control just loses color data that can of course never be re-created in post, because ... the data isn't recorded.
Log ... the cameras that work in full Log mode record in specialized processing-to-chip. And to make a log format really work, it needs to be shot in 10-bit color mode, not the 8-bit that is all the bit-depth nearly all drones and DSLRs can create. The log-capable cameras also typically record a greater dynamic range than 'standard' while in Log mode, maybe 2-4 full stops worth of data off the sensor, and pass the entire range to card but in a special way. Although it appears on-screen in a very narrow or "flat" image from medium grey to light grey and with very low saturation, the actual full data for all the contrast range & saturation is still encoded to disc. Not the same as "flat" 8-bit at all.
The starting point in the difference between flat & log is that Log has often several times the data actually recorded to file!
RAW ... here, the full unprocessed input data to the sensor is recorded to disc without processing in the camera. A lot more data to work in post-processing even than log media.
As to different log forms ... yes, the various camera makers tweak the log format for their camera's sensor/processor capabilities and needs. They then create LUTs (Look Up Tables) that are designed very specifically to apply major curves work to alter the luma & chroma data to essentially reverse-engineer the log encoding into a "normal" looking say Rec709 color space. Many camera makers for those rigs make several LUTs per camera, to use for different color spaces in post.
Realistically, for most of the log media I've worked with, I can create a LUT to "normalize" the media that I may well prefer to the camera maker's LUT in fairly short time. So ... I've just made my own from scratch. I learn about that particular media along the way, which is useful.
A typical log workflow is to apply a corrective or "normalization" LUT to a clip, then do the neutralizing of that media in front of the LUT. In other words, put the normalization LUT in place, then do the neutralizing of color & tonality through the LUT.
In PrPro, that would mean using the Lumetri panel's Creative tab "Look" slot to apply the normalization LUT, and ... because the order of processing through Lumetri is strictly top to bottom, go back to the top of the Basic tab and use the temp, tint, and tonal controls to get them most natural/neutral looking image possible.
Then you go to the controls in the Creative tab, Curves, Color Wheels, and HSL to "complete" the grading work.
...............
The media you were given from that GoPro is highly compressed H.264 8-bit, and ... is what I think of as "thin" media, in that it's not got enough data to take much of a change of values without macro-blocking.
Notice in the hills to the left-center background, if you do much to push tones up or down, and start playback, you start seeing big blocky chunks with no data ... just flat groups of squares? That's macro-blocking. It was the biggest problem to try & do something with this ... if I did much of anything, I'd get m-b.
Think of your tones light to dark as being a rubber stretchable band. If you grab in the middle, and pull towards one end, that 'near' end band gets a bit thicker as you're pushing material towards that end. But look at the end you're pulling away from ... it gets thinner ... there's less material there. If you start with a very thin and hard-stretched rubber band, only a little pull from the middle to one end can cause the band to break.
That's your media. A very thin rubber band, essentially.
And as far as curves versus the other tools of the User Interface ... most of the "tools" in color correction actually work the same with the media as a curves tool would ... it's just the interface control uses a different "look", and feels a bit different while using it.
Neil
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