C300: Where Do You Put 18% Gray in Wide DR Gamma?
- Thread starter Dino
- Start date
AndrewTaran
Active member
Where do you put grey card when shooting c-log? Thanx
Jazzy Moire
New member
What exactly do you mean Dino? Are you saying that you balance the camera before every shot with a 18% gray card? And I just looked up IRE on Wikipedia and wonder what you are talking about.
Wikipedia says that ' The sync pulse is normally 40 IRE below this 0 IRE Value, so that the total range covered from peak to trough of an all white signal would be 140 IRE'
But what all of this means baffles me and I've had a C300 for over 2 years. [FONT=Helvetica Neue, Helvetica, Arial, sans-serif]
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Dino
Veteran
IRE or percent on a 0-110 scale waveform are the same. I expose C-Log indoors at 38% and 32% outdoors with an 18% gray card. The card is a better reference than skin tones. In C-Log, reflected whites are typically at 70%.
Wide DR does not protect for highlights as much as C-Log. Whereas C-Log offers about 30 units of highlight protection, Wide DR looks to be more like 20 units. Haven't been using the latter very long, you C100 owners have more experience with it.
Wide DR does not protect for highlights as much as C-Log. Whereas C-Log offers about 30 units of highlight protection, Wide DR looks to be more like 20 units. Haven't been using the latter very long, you C100 owners have more experience with it.
AndrewTaran
Active member
Could I ask you what is the exact exposure difference between 32%-38%(as Canon suggests) and 50%? I usually don't have time to measure grey card(I shot doc style 90% of the time), but I do have a light meter. So, let's say my light meter reads f/4, ISO 850, 1/48th, what my f-stop should be to get close to 32%-38%? Thanx
Dino
Veteran
So differences in exposure are very dependent upon gamma, especially very nonlinear gammas like log, as well as resolution, shutter and frame rate. Here are examples of f-stop vs. IRE with three different gammas: (the values are only valid relative to each other)
C-Log
f4 = 50IRE
f5.6 = 38
f5.6 1/3 = 32
Norm 1
f5.6 = 50
f5.6-8 = 38
f8 = 32
Wide DR
4 2/3 = 50
5.6 = 38
5.6 2/3 = 32
it's also worth looking at reflected whites, C-Log is at 70IRE, Norm 1 is 90, Wide DR is 80, putting 18% gray at 40IRE. So that tells us that C-Log gives 30IRE of highlight protection, Wide DR 15, Norm 1 10. I find that flesh tones should not exceed 50IRE in C-Log.
C-Log
f4 = 50IRE
f5.6 = 38
f5.6 1/3 = 32
Norm 1
f5.6 = 50
f5.6-8 = 38
f8 = 32
Wide DR
4 2/3 = 50
5.6 = 38
5.6 2/3 = 32
it's also worth looking at reflected whites, C-Log is at 70IRE, Norm 1 is 90, Wide DR is 80, putting 18% gray at 40IRE. So that tells us that C-Log gives 30IRE of highlight protection, Wide DR 15, Norm 1 10. I find that flesh tones should not exceed 50IRE in C-Log.
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AndrewTaran
Active member
Thank you, Dino! So in this case Caucasian skin tone should be at 50%(f/4)?
Dino
Veteran
Yes, for C-Log. Haven't done a lot of shooting in Wide DR yet, but 55-60 IRE seems to be okay. Flesh tones vary a lot, so 18% gray card is the best reference.
I'd really like to hear from C100 owners who have a lot of experience shooting with Wide DR.
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Isn't an 18% grey card supposed to equal about a stop darker than Caucasian skin? I always understood that, on a normal video gamma, you'd expose the grey card to be at 50% on the waveform, and then "normal" Caucasian skin would be therefore peaking at about 70% IRE. Is that right?
Dino
Veteran
Interesting, skin highlights can be a lot higher than overall skin tone, of course. The moment cameras came out with any kind of Cine gamma, I stopped putting flesh at 70%, starting with our Panasonic HDX900, back in 2008. Depending on how aggressive the gamma curve or where knee and slope are set, I often see compression in the skin tone when set to 70%. Additionally, I think when we changed to flat panel displays, compared to properly setup CRT's, we lost contrast and tonality, so putting flesh lower than 70% can be useful even for REC709 gammas.
I haven't had enough time to get to know Wide DR gamma, but like any Cine gamma, if you put flesh at 70%, you're losing the highlight protection that Cine gammas offer, besides the possibility of skin tone compression that often comes with those gamma curves, if set too high. Maybe Knee Saturation is helping to mask the skin tone compression? I always turn Knee Saturation all the way down with every camera, as I don't think it looks natural.
I haven't had enough time to get to know Wide DR gamma, but like any Cine gamma, if you put flesh at 70%, you're losing the highlight protection that Cine gammas offer, besides the possibility of skin tone compression that often comes with those gamma curves, if set too high. Maybe Knee Saturation is helping to mask the skin tone compression? I always turn Knee Saturation all the way down with every camera, as I don't think it looks natural.
Dino, I'd be interested in hearing your thoughts on the quality of my footage. Here's a video I did for Make-A-Wish. This was all pretty run and gun with lots of very challenging, mixed lighting conditions. I used the zebras set at 70% as my guide. I was also using Paul Frederick's "Wide PF" profile, which I really enjoy: https://vimeo.com/77931546
Argh! That was the link to the video that introduced us to Paul Frederick's Wide PF profile, based on Wide DR. My images are not quite in that league: https://vimeo.com/89411085
Dino
Veteran
That was a very nice piece. I thought most of the flesh tones looked good. A few felt a bit hot and plasticky, but that could have been AVCHD or Vimeo compression. You might try just backing down 5 IRE on skin tones and see what you think.
I really wish Canon would have addressed zebras below 70 IRE by now, big omission, especially after two years on the market.
I really wish Canon would have addressed zebras below 70 IRE by now, big omission, especially after two years on the market.
nedcam
Well-known member
Nice work Drummondb! What lenses did you two use? That is my style of shooting 60% of the time, zebras at 70% but when it's a light skin Caucasian I back down so I am right before 70%. Like Dino said it's too bad we can't dial in zebra setting so we have a safety zone. On some of my cameras I am able to set it at 65-67%. African Americans I guesstimate. When handheld I can't afford to take my hands off the camera and hit the waveform.
What is really helping me now is I have done enough shooting with the combo of the C100 & DP4 that I can "eyeball" my exposure when doing run n gun and I am now right on the money. In situations like your example I care only about the faces since that's what the viewer (and clients) will be zeroing in on. For instance, when the girl is in the wheelchair outdoors her gloves are hot but you got the face perfect, and that's what matters.
I will try the Paul F scene file next gig but I did not feel your skin tones were warm like I prefer them. Did you do much CC in post?
What is really helping me now is I have done enough shooting with the combo of the C100 & DP4 that I can "eyeball" my exposure when doing run n gun and I am now right on the money. In situations like your example I care only about the faces since that's what the viewer (and clients) will be zeroing in on. For instance, when the girl is in the wheelchair outdoors her gloves are hot but you got the face perfect, and that's what matters.
I will try the Paul F scene file next gig but I did not feel your skin tones were warm like I prefer them. Did you do much CC in post?
Thanks! I believe the only 3 lenses used were the Canon EF-S 17-55mm f/2.8 IS, the Sigma 24-70mm f/2.8, and the nifty-fifty 50mm 1.8 for the talking head shots in the first half.
As for grading, the first half of the video (the restaurant scenes) didn't have much correction applied at all. Maybe some tweaking of levels. In the second half of the video, the homeless shelter had some horrible yellow lights of various temperatures in different ends of the large room. Even though we did a manual white balance with a few sheets of printer paper, the color still looked pretty awful. I used Colorista II to do some one-click white balance correction, and then played with the strength a little so as not to totally change the look of the actual location. I mean, hey, the place was bathed in a nasty yellow light, so I didn't want to totally ignore that reality.
I love the C100, but I REALLY struggle with getting color temperature right. And the LCD doesn't help. Colorista II has saved my bacon many times with white balance, but it takes ages to render.
As for grading, the first half of the video (the restaurant scenes) didn't have much correction applied at all. Maybe some tweaking of levels. In the second half of the video, the homeless shelter had some horrible yellow lights of various temperatures in different ends of the large room. Even though we did a manual white balance with a few sheets of printer paper, the color still looked pretty awful. I used Colorista II to do some one-click white balance correction, and then played with the strength a little so as not to totally change the look of the actual location. I mean, hey, the place was bathed in a nasty yellow light, so I didn't want to totally ignore that reality.
I love the C100, but I REALLY struggle with getting color temperature right. And the LCD doesn't help. Colorista II has saved my bacon many times with white balance, but it takes ages to render.
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Dino
Veteran
I've done more tests with Wide DR and find that exposing 18% gray at 40% can put skin tone at 70% and it looks fine, doesn't seem to have the compression issues of C-Log when skin tones go much above 50%. Wide DR seems to be different from other Cine gammas that I've used from Panasonic, Sony or Canon.
nedcam
Well-known member
Slightly off thread since this response is about C100 WB being less than desirable:
Drumondb,
I too hate the way the C100 misses getting the color temperature correct in mixed light, actually anything that isn't pure tungsten or daylight. I was thinking of buying a color temperature meter (haven't had one since my 16mm days) but when my research showed they are around $1200 I dropped that idea. I have warming cards from Vortex Media and they warm it up a little. But all in all, if you are a freelance shooter who will pass on the raw footage to an unknown post person, it is really a bad situation in terms of getting the temp right, similar to my last cam the AF100. Ergonomically the C100 is very good for doc shooting but in terms of grabbing WB correctly, I have been VERY disappointed. Really skews toward green in the default Wide DR settings.
I have tweaked my DP4 EVF to simulate what the final result will be exposure and color wise, but there is no way the built in LCD will give me any confidence if I got it right. I was going to start a thread on it but... it is what it is. This forum seems to be divided between those who have all the time in the world to set up and tweak, and the other half who have to pull the camera out of a bag and roll all day cinema verite. I'd say much of my work the last few years is in the latter category so I wish I could be more confident of my WB. I do fill the ENTIRE frame with a white card, or warm card, per the manual.
Fortunately, I am now so old I can look at a situation and "guesstimate" the kelvin so if what is reported in the VF is what I consider to be "way off", I slow down and try to figure it out. My DP6 is very untrustworthy, besides, I move so fast it stays in its case 90% of the time. It will be on Ebay soon.
When I watched your video I freeze framed when a cameraman was in the shot (drives my wife nuts) to study your set up, I realize you aren't a candidate for an EVF rig, but if you could set up a rig with an EVF you trust, and tweak exposure & kelvin to simulate what you see in your timeline (focus is another story), then you would be better off in terms of run n gun. At first I was pissed there were no zebras in the DP4 but now I am very good at "eyeballing" my exposure. I learned to do this by importing my footage every night after a shoot and learning when I was too hot or under. Color temp is another story though, so I cheat a bit.
When video was first invented I would pick out the crew member who had the most washed out blue jeans and balance on his thigh to warm things up. Then my friendly Boston competitor Doug Jenkins invented Warm Cards and made so much money he could quit the grind. I would strongly suggest buying:
http://www.vortexmedia.com/WC1.html
That will warm things up but if you're way off WB in the first place it won't help.
Drumondb,
I too hate the way the C100 misses getting the color temperature correct in mixed light, actually anything that isn't pure tungsten or daylight. I was thinking of buying a color temperature meter (haven't had one since my 16mm days) but when my research showed they are around $1200 I dropped that idea. I have warming cards from Vortex Media and they warm it up a little. But all in all, if you are a freelance shooter who will pass on the raw footage to an unknown post person, it is really a bad situation in terms of getting the temp right, similar to my last cam the AF100. Ergonomically the C100 is very good for doc shooting but in terms of grabbing WB correctly, I have been VERY disappointed. Really skews toward green in the default Wide DR settings.
I have tweaked my DP4 EVF to simulate what the final result will be exposure and color wise, but there is no way the built in LCD will give me any confidence if I got it right. I was going to start a thread on it but... it is what it is. This forum seems to be divided between those who have all the time in the world to set up and tweak, and the other half who have to pull the camera out of a bag and roll all day cinema verite. I'd say much of my work the last few years is in the latter category so I wish I could be more confident of my WB. I do fill the ENTIRE frame with a white card, or warm card, per the manual.
Fortunately, I am now so old I can look at a situation and "guesstimate" the kelvin so if what is reported in the VF is what I consider to be "way off", I slow down and try to figure it out. My DP6 is very untrustworthy, besides, I move so fast it stays in its case 90% of the time. It will be on Ebay soon.
When I watched your video I freeze framed when a cameraman was in the shot (drives my wife nuts) to study your set up, I realize you aren't a candidate for an EVF rig, but if you could set up a rig with an EVF you trust, and tweak exposure & kelvin to simulate what you see in your timeline (focus is another story), then you would be better off in terms of run n gun. At first I was pissed there were no zebras in the DP4 but now I am very good at "eyeballing" my exposure. I learned to do this by importing my footage every night after a shoot and learning when I was too hot or under. Color temp is another story though, so I cheat a bit.
When video was first invented I would pick out the crew member who had the most washed out blue jeans and balance on his thigh to warm things up. Then my friendly Boston competitor Doug Jenkins invented Warm Cards and made so much money he could quit the grind. I would strongly suggest buying:
http://www.vortexmedia.com/WC1.html
That will warm things up but if you're way off WB in the first place it won't help.