Shooting Log

[clyde villegas]

I hope this is the correct forum for my question. I'm using a Panasonic GH5 with V-log L.

 

I'm a bit confused on using V-log L. I was told that the reason for using log in general is to save the highlights (especially the sky in outdoor shoots). But in most forums, they are advising to over expose the shot to get rid of the noise in the shadows. But doing this blows out the skies.

Therefore, I think there is no sense in shooting with log. Just shoot with a standard profile and light the scene correctly as v-log can't save both highlights and and shadows at the same time. The problem is, it's not easy to do this when shooting outdoors run and gun in the morning when the sky is in the shot. Am I thinking correctly or am I missing something? Thanks! God bless!

[David Mullen ASC]

Then dont overexpose to the point that the sky is clipped. At some point, you do run up against the dynamic range and noise limitations but the point of log is to preserve more highlight detail but you negate that if you overexpose the image too much.

 

Depending on the camera, log records two or more stops over Rec.709 display gamma. But the higher contrast of Rec.709 does mask a certain amount of noise. At some point, your log image is color-corrected for Rec.709 display gamma but you have more flexibility in corrections with that extra highlight information (if you didnt overexpose too much.)

 

The point is that you monitor and light for Rec.709 but record log to have more information to work with in post (this requires a way to apply a Rec.709 LUT for your displays on set, or output Rec.709 but record log.)

[clyde villegas]

Thanks David!

 

Also, when I "normalize" the shot in post either by applying rec 709 LUT or by bringing back the contrast (or saturation?), it looks like it's shot with a normal profile. No more wide dynamic range (I'm not a professional colorist so I may be wrong). So is it safe to say that log provides wide dynamic range for the colorist to play with, not to the final image the audience is going to watch?

[Robin R Probyn]

Yes thats exactly it.. but you'd be surprised how many "producers" dont understand that.. and its become the "flat look" . I swear there are people putting straight log footage out to air.. you can see it all over the web.. scary times..

[David Mullen ASC]

Your display is showing around 10 stops (unless it is HDR) and your log recording has 12 stops, more if you are using a better camera. If you just slap a conversion LUT, you’re probably just going to lop off those extra stops, but if you apply some more advanced color-correction tools, then you can use that extra information like to hold detail in a hot lamp shade or window. But this requires you don’t overexpose log to the point where the headroom is the same as Rec.709 unless it is just more shadow detail are aiming for. To take advantage of log, you usually use things in color-correction like knee compression and power windows to bring detail into hot areas, and some of these tricks don’t lend themselves to just using a consistent LUT over all the footage.

 

A compromise between log and Rec.709 if you have a camera recording 8-bit or one that has noisy shadows is a form of HyperGamma, a flatter Rec.709.

[clyde villegas]

Thanks David! I understand. I should do some isolated color grading instead of grading the entire frame by slapping on a LUT.

 

I've seen people using the Leeming LUT or the GHAlex LUT. The creator of the GHAlex LUT promises to make GH5 V-Log L shots to look like Alexa shots. So my plan was to buy the GHAlex LUT, slap it on my V-Log footages as a starting point, and then grade them. However, looking at some samples, I don't like what the GHAlex LUT does with the highlights: they appear to glow and remove some of the details. Can I use this LUT, and then adjust the highlights to bring back the details (after the LUT destroys them)? Is this a good workflow?