GH4 V-Log L questions

F

funkytwig

Active member
Hi. I've read quite a lot about the V-Log L profile but still not totally clear about how to set exposure. From what I can gather I need to over expose by between 1.5 and 2.5 stops. When I shoot with normal profiles I find the exposure meter at the bottom of the viewfinder works well. I tend to combine this with zebras and histogram.

So do I simply set the exposure compensation between 1.5 and 2.5 stops depending on the scene. If this is the case not realy sure how to decide where to set it in the 1.5 to 2.5 range?

I am also getting the feeling ugine V-Log L in low light is a little tricky as with a 2.8 lens i am generally at 25fps and ofter 1600 ISO so over exposing anyt really an option (I tend to do a lot of run and gun documentery and ofter I cant change the lighting).

Lastly do I need to expose diferently for 4K and 1080P. The stuff I have read about 4K seems to indicate it needs more light, or does the exposure meter cater for this?
 
DLD said:
http://www.thehurlblog.com/panasonic-lumix-dmc-gh4-vlog-l-latitude-test-cinematography-education/
Click to expand...

Interesting, so it seem for skin tone underexposing 2/3-1 stop is the sweet spot. This is the opposite of what everyone else seems to be saying in terms of exposing with v-log. It is also good because it is generaly for me overesposed skins tones which are the bigest problem and under exposing can help this a bit. Crushing blacks is a personal preference but for me I would rather have slightly crushed blacks (unless they were on the skin/heir), than blown whites.

Now this is a very specific test concentrating on skin tone only. It is ignoring everything else. This means that in documentary terms it is mainly useful for interviews and actuality people, whitch nost it;). I am wondering if it is still apropreat for landscape or even filmimg theatre/caberet.

It also does not answer my question in terms of how to expose in run and gun. My feeling is using exposure conpensation of -1 or 2/3 is also the way to go.
 
I'm running my GH4 in:

ISO 800 (so it closes the aperture down a bit)
Shutter Priority Mode
180d Shutter
+2 Ex Comp
Zebras at 75%
 
http://pro-av.panasonic.net/en/dvx4k/pdf/ag-dvx200_tech_brief_vol6_en.pdf

More great information. Basically you could get by with the tools in the GH4 to expose v-log in a run&gun situation. Not the easiest thing to do but it is possible. Due to a luma range bug on most monitors/recorders out there when a camera uses 0-255 range I actually prefer exposing with the GH4 LCD vs an external monitor.

Zebras at 75% (to protect color channels clipping) is a pretty safe way to shoot and make sure you are not clipping anything. The second zebra at 55% helps with lighter skin tones. Using the spot meter is pretty "spot" on as well. Use it in spot mode on a gray card to nail exposure. A spot meter of 0 on a gray card is about the same as False color at 42 IRE on my external Blade monitor. Even with the luma bug since the curve adjustment doesn't change much in the middle. The overall exposure meter that judges the full scene is pretty accurate as well. It may be a bit off depending on the contrast of your scene and the ratio of light to dark portions of the screen but it is a good ballpark tool to use. Nail exposure at 0 (white) and you should be within 1 stop below or above which is more or less safe. I use a combo of the exposure meter, histogram and zebras to tell me if a shot is at least in the ballpark of where it needs to be. Exposure meter tells me if I'm about where I need to be. The zebras tell me if I have too much clipping and either need to rethink the lighting or stop down to under expose a bit. The histogram gives me a crude picture of how the values line up in the shot so I know if they are way off. none of these are super accurate tools but they get the job done.

I find using the exposure meter in spot mode is pretty darn accurate if you have a gray card. Not exactly something you will use all the time in a quick setup or run&gun situation. If you are shooting an interview however it takes seconds to have the subject hold a gray card and check the exposure with a spot meter.

As to the subject of under or over that is up for debate. It really comes down to what do you prefer less noise or more accurate color. It is tradeoff that only you can decide which way you want to go. By going over by 2 stops I have managed to get ISO 3200 to look clean with V-log once you grade it down. The color suffered a bit however so it becomes a subject of what is more important to you. To be honest I have not noticed the massive color loss to the extent Shane has shown on his website. I do agree with Barry however that you are not giving yourself much room in the highs if you ETTR or over expose. It is kind of dangerous to shoot that way and you have to be very careful. ETTR does have some very significant advantages however especially when it comes to noise. The GH4 loves light and a healthy bright exposure really helps reduce noise on the GH4. Like I mentioned earlier I get very clean results with ISO 3200 when shooting 2 stops over. There is clipping however. If we has a 14 or 15 stop sensor like the Varicam we would have more room at the top but alas we do not.
 
OK, thanks for that, very encouraging. One thing that made me chuckle was "By going over by 2 stops I have managed to get ISO 3200 to look clean with V-log once you grade it down". One thing about run&gun is you cant light stuff. So going 2 over at 3200 seems to mean you need glass that can shoot at 800 (that being the exposure you do 3200-2 stops). I tend to use 2.8 glass and a lot of the time I struggle not to go to 1600 and the meter still puts me a couple of stops under. I could get a voylander but for run and gun the zoom is almost essential. I shoot most of my inside stuff on a 12-35 2.8 panny lens. Yes I have to live with some noise but the reality is unless you are shooting raw its better to use higher ISO than push in post (because this pushes the uncompressed date, if you push after you are pushing compressed date).

What is ETTR?

I can definitely see how over exposing helps noise but as I have said its a difficult thing to do in some of the situations I shoot.

I am also interested in the NR and Sharpness settings with V-log (and other profiles). I can certainly see going -5 for sharpness is a good thing as the GH4 is a sharp camera and sharpening reduces the reality of an image by sharping up some of the subtle texture. NR is another thing. If i am shooting 800 or 3200 and going 2 stops over I can see NR of -5 makes sense but if I am shooting in low light and having to push ISO some NR may be good as it is always best to do this in the camera rather than post as in camera NR is working on uncompressed date.

Basically it is always best to do NR/sharpening in camera than post so if you know you are going to need to do it in post do it in camera.

as always its horses for courses and I immediately distrust people giving settings without saying the type of thing they e shooting (although if it is for drama when you have full control of lighting it is possible). I tend to think in a couple of general types of situations.

* Bright sunshine with shadows requiring the greatest dynamic range but having a lot of light (maybe for this overexposing by 1.5 stops with -5 sharpening and NR at -5).
* Dark situations where you need to push ISO and crushing some of the blacks in not a problem, personally I don't mind losing a bit of details in the shadows at night, in very dark rooms as this is kind of what the eye does (maybe underexposing by a stop, sharpness -5 and NR 0). Not sure what ISO I can get away with but 1600 may be OK. I will do some 3200 tests but don't hold mutch hope.
* Daytime without direct hard/bright sunlight or lit interviews/scenes (again underexposing by a stop but -5 NR and sharpness).

Just guidelines but a lot better then one size fits all IMHO.

Lastly, it is a real shame you cant put a LUT on the screen/viewfinder. Its not as easy to see things in a flat image and also having a realistic image in the viewfinder helps spot if White Balance is wrong (verry usefull for hectic run&gun where you are shooting inside and outside, hell there are a cople of times I wished I had used automatic white balance!).
 
Last edited:
funkytwig said:
OK, thanks for that, very encouraging. One thing that made me chuckle was "By going over by 2 stops I have managed to get ISO 3200 to look clean with V-log once you grade it down". One thing about run&gun is you cant light stuff. So going 2 over at 3200 seems to mean you need glass that can shoot at 800 (that being the exposure you do 3200-2 stops). I tend to use 2.8 glass and a lot of the time I struggle not to go to 1600 and the meter still puts me a couple of stops under. I could get a voylander but for run and gun the zoom is almost essential. I shoot most of my inside stuff on a 12-35 2.8 panny lens. Yes I have to live with some noise but the reality is unless you are shooting raw its better to use higher ISO than push in post (because this pushes the uncompressed date, if you push after you are pushing compressed date).

What is ETTR?

I can definitely see how over exposing helps noise but as I have said its a difficult thing to do in some of the situations I shoot.

I am also interested in the NR and Sharpness settings with V-log (and other profiles). I can certainly see going -5 for sharpness is a good thing as the GH4 is a sharp camera and sharpening reduces the reality of an image by sharping up some of the subtle texture. NR is another thing. If i am shooting 800 or 3200 and going 2 stops over I can see NR of -5 makes sense but if I am shooting in low light and having to push ISO some NR may be good as it is always best to do this in the camera rather than post as in camera NR is working on uncompressed date.

Basically it is always best to do NR/sharpening in camera than post so if you know you are going to need to do it in post do it in camera.

as always its horses for courses and I immediately distrust people giving settings without saying the type of thing they e shooting (although if it is for drama when you have full control of lighting it is possible). I tend to think in a couple of general types of situations.

* Bright sunshine with shadows requiring the greatest dynamic range but having a lot of light (maybe for this overexposing by 1.5 stops with -5 sharpening and NR at -5).
* Dark situations where you need to push ISO and crushing some of the blacks in not a problem, personally I don't mind losing a bit of details in the shadows at night, in very dark rooms as this is kind of what the eye does (maybe underexposing by a stop, sharpness -5 and NR 0). Not sure what ISO I can get away with but 1600 may be OK. I will do some 3200 tests but don't hold mutch hope.
* Daytime without direct hard/bright sunlight or lit interviews/scenes (again underexposing by a stop but -5 NR and sharpness).

Just guidelines but a lot better then one size fits all IMHO.

Lastly, it is a real shame you cant put a LUT on the screen/viewfinder. Its not as easy to see things in a flat image and also having a realistic image in the viewfinder helps spot if White Balance is wrong (verry usefull for hectic run&gun where you are shooting inside and outside, hell there are a cople of times I wished I had used automatic white balance!).
Click to expand...

ETTR = Exposure to the Right. Means exposing the image brighter so the histogram sits more on the right side.

Noise reduction in camera = bad, ugly, poopoo
Noise reduction is a very complex process and good software applications like NeatVideo can't even perform in realtime on a top of the line quad core computer with a beefy graphics card. How can you expect the CPU in a DSLR to do better with 4k frames 30 times per second without dropping frames or over heating? Even with all that processing power NeatVideo still isn't 100% perfect. The poor little GH4 is already using a lot of processing power to make a good looking video image. Not much left for high quality NR. I believe one of the key reasons why newer m43 cameras seem to handle low light better doesn't have as much to do with a brighter sensor but the cameras doing much better noise reduction.

The GH4 loves light and anytime you underexpose the shot you will have ugly noise. If you need to use ISO to see then make sure you use enough to see properly. If you increase the ISO but it still isn't enough for a good even exposure you will see a lot more noise than you should.
 
The reason I bought a Atomos Ninja 2 is to use the false color feature to nail exposure every time. I know it's not ideal for run and gun, but it certainly solves exposure worries.
 
You must log in or register to reply here.
Back
Top