Log color wheels

When it's best to use Log color wheels and when it is not?

in my experience, they should never be used for contrast adjustments

They're great for working on a very specific range. I use them to adjust a highlight without affecting the overall white balance of a shot, or to pull down just the really deep shadows without making the shot feel crushed. You just have to get used to adjusting the range highlight or shadow range, leaving it at default can give you pretty grim results.

As Tom says, I wouldn't use them for large contrast adjustments or overall image balancing.

Cool! Thank you guys!
So it's not about dealing with Log footage at all as I thought, correct?

No, not really. The manual goes into detail on how log-encoded footage should be "normalized" and then adjusted first with the offset wheel and then the log controls (as well as contrast and pivot), both of which should precede the normalization in node order.

Can't say I've had great success with it myself -- the primary controls seem to provide better results, preceding the normalization -- but maybe the professional graders here can go into more detail.

I've found it quite handy to control highlights on log footage pre-LUT. Very useful if someone's shot something a bit too hot and you need to reign it back in to avoid a LUT slicing it off.

I like using offset controls for log material, and I use the "log" controls to remove small unwanted peak white tints or when I need either to deep the blacks a touch or flatten them a touch.

It not specially for log footage no. Its like the lift gamma gain but you can choose a range and a pivot of applying this. Very useful!

I'm very new to grading but I have found the Log controls to be extremely useful. I like the way they only have an effect on a narrow region, like extreme highlights, and won't throw of the rest of the image. The fact that you can adjust the range that they effect is very handy as well. Overall, it's one of main reasons why I can't bear to use FCPX, even with Color Finale, to grade footage.

No, not really. The manual goes into detail on how log-encoded footage should be "normalized" and then adjusted first with the offset wheel and then the log controls (as well as contrast and pivot), both of which should precede the normalization in node order.

One of the powerful features of Resolve is that there's often a half-dozen different ways to accomplish the same thing. You could use a normalizing LUT; you could use curves; you could use contrast and pivot; you could use primaries; you could use the log controls. I'll try different methods for different projects, but there's many ways to get this to work. I go with whatever's fastest and gets the best results.

I personally think the Log controls are dangerous and can wreak havoc (particularly mids), and I prefer to use only the Shadows adjust blacks at the end of the node tree. On rare occasions, I'll tweak the whites with Highlight, but you can also do this with white clips or a luminance curve.

If the footage is Raw, then I would add you need to make the Camera adjustments first, because that is the very first level in the processing chain.

The Log Color Mode in Davinci Resolve has been designed to normalize encoding media, specially when dealing with high compressed ones.
The log mode can be taken as a fine tuning tool compared to the Primary Color mode. However, nothing stop us to use it as a creative tool in non log media.
The flip side of the same coin: it’s advisable to avoid starting to normalize a log encoded media with the Primary mode because the increment per steps in the controllers cover a larger range, which makes this mode subtable for non log encoding media, in other words, less compressed media.

Alexis van Hurkman in his Color Grading in Davinci Resolve 11 series has a video tutorial entitled “Log Color Grading,” where he has an illustrated example explaining the distinction of using both modes, when and how to combined them using log encoding media. Definitely, the Log mode shines best when used in log encoding media.

i use the log wheels on my base node typicaly

I do most of my work in exposure/contrast/pivot/saturation/high & low log wheels, i'm not likely to use lift/gamma/gain untill the last node, unlikely to touch hue offsets (the balls are set to responce=1 on my systems) atall

i work the same with log encoded footage in YRGB, and linear footage in ACES

I rarely touch 709 encoded footage, but if it does cross my bow, i'd guess LLG woud be the starting point then, and log wheels would be of less use, or as other have mentioned for a controlable tweak of shadows

i do work in log mostly, with a lut/lut+look at the end, and i approach like this:

1) normalize the color space (if needed)
2) main exposure/WB in offset
3) main contrast with the gain ring
4) tinting with the gain balls if needed

then i use the log control to clean black and white if needed, but is just about 10% of the time and a very small amount

In the spirit of trying to add knowledge to threads that exist, rather than starting a new thread...

I created a timeline with a grayscale ramp as my subject. I observed the behavior of the LOG wheels as I adjusted the Low and High ranges. What I found shocked me.

The Low and High ranges seem to round off their anchors to the nearest 0.05, which means that changing the range from .29 to .30 results in a discontinuous jump that can be easily observed. Along these same lines, the distance of the overlap ramp between shadows and mids and the ramp between mids and highs is 0.5 each, which means that when the two are separated by 0.1 or less, the midrange is effectively disabled. So much for using the midrange control to make precise adjustments to a narrow range of luminance values.

I will note that lots of the pros (who weighed in earlier on this thread) all kinda say the same thing: don't trust the mid controls for anything. Use only sparingly to adjust highlights and shadows. When used very sparingly, the jarring jumps of the 0.05 detents are not very visible. But if you want to make a 10 IRE adjustment to a range of values in your image, THIS IS NOT THE TOOL FOR THAT! Custom curves are better for that.

Unfortunately the Mini Panel doesn't offer an easy ability to set the start/end range for curve influence, only the gain/cut of fixed position points. There is some kind of way that it maintains correspondence to its initial default anchors (0-20-40-60-80-100) after you move the points around on the X axis, but it's not clear when it will lose the connection to those points and create another. I'm guessing that +/- 5 is the max safe range of movement. I also notice that if I create additional points between the default anchors, those extra points can be used to constrain the influence of those anchors, but again if the center I want to control is 30, I can move the 40 point to the 30 line, but if I then add a constraining point at 40, the panel gives up on my 30 point and starts controlling the 40 point. There's no good way to use the panel to control the range 20-40 centered at 30. (At least not that I can find.)

The Low and High ranges seem to round off their anchors to the nearest 0.05, which means that changing the range from .29 to .30 results in a discontinuous jump that can be easily observed. Along these same lines, the distance of the overlap ramp between shadows and mids and the ramp between mids and highs is 0.5 each, which means that when the two are separated by 0.1 or less, the midrange is effectively disabled. So much for using the midrange control to make precise adjustments to a narrow range of luminance values.

As I said 3 years ago, I never use the mid Log controls because of the dangers of distorting the signal. I am a fan of using the log Shadow control to carefully sculpt the blacks when necessary. I'll do the same thing with Highlights, particularly if the Highlights are skewed into a weird direction; I had a situation the other day with a very blue scene where I didn't want some car headlights to go blue, so the Log Highlight control worked perfectly to get them in a better-looking direction. I'll use the High Range control to fine tune the degree of what gets affected, which is exactly how it's intended. I couldn't give a crap about what the numbers are -- I only care about the pictures and the results.

I will say that the Log controls in Baselight work quite a bit differently from how they work in Resolve, and there's some validity to Filmlight's approach. You can do more with the Log controls in Baselight, but as always, I say that good colorists can work in any system and get good results.