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film rec vs vid rec? mystery solved
What does Film Rec do exactly in the varicam?
Well, thanks to Lew Comenetz’s suggestion, I did some playing with the camera and a waveform and came up with the answer.
Lew, a very experienced video engineer, had said to me that the Film Rec seemed like just a knee function, especially because one needs to have the manual knee turned on in the menu to activate the Film Rec mode.
I tested this out today using the camera’s Test Saw (it’s a camera generated gray ramp) and the waveform monitor. What I found is that Film Rec mode simply sets the Knee Point setting to 10% video. That’s it.
It should be noted that the lowest Knee Point setting in Video Rec is 30% and that is the difference between Film Rec and Video Rec. In Film Rec the Dynamic Level setting is the same as the Knee Slope setting in Video Rec.
The only other difference is that there is an additional control in Film Rec called “Black Stretch Level”. Black Stretch Level is a gamma control that works with more emphasis in the darker half of the image. It can only be used to decrease gamma (make the image lighter with less contrast). It is a very different control than “Black Stretch” which only effects the very darkest part of the image, and works in both directions.
That’s it. At least for me, mystery solved. There seemed to me so much confusion about the Film Rec vs. Video Rec modes that I thought some of the technical minded here would be interested.
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13 Replies
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Bruce,
You are correct in conceiving of the Film Rec settings as takeing over control of the knee function; it basically replaces the variable knee point and slope settings with four presrts, namely 200,300,400 and 500% Dynamic Level. The more highlight compression (or the flatter the negative you desire) the higher you go with the setting. Three other things also happen as you go higher; the crossover of the gamma raises, the color desaturates and the speed or sensativity of the camera decreases. So now you have four things happening!
When you intend to use your footage in a “what you see is what you get” environment, that is, without extensive (meaning Da Vinci-type) color correction in post, or without an intended film-out (which increases the contrast again) you should consider “crushing” the gamma (raising the number from nominal .45 to .50 and .55) as you invoke more dynamic level. This restores the mid and lower blacks and adds some color saturation back in also. You still have the “black stretch” control of -1,-2,-3 in addition to keep the picture “crunchy” and less washed-out, or the plus control in dark scenes.
The problem inherent in all this is that each shot, depending on how much highlight correction is necessary might require an adjustment of the gamma and black stretch as well. which can be confusing to keep up with in a typical production environment. That’s why it’s so important to have a VC or DIT with proper test gear, monitor and CCU to keep track of all this stuff, once you’ve all decided on a protocal and “look”.
What you’ve done is precisely what is required to learn, understand and ultimately gain the requisite confidance to use these controls creatively. It takes careful observation (aka testing) with a chart and a waveform/vectorscope and remote CCU in a calm (non-production) environment, where you can take as much time as necessary to calmly make your observations. This would be a perfect environment too to observe how your favorite filters behave as well! You can use what you’ve learned directly in making your own settings or to “speak the same language” with A VC/DIT.
As regards the Test Saw, what’s really happening is that at the 500% DL setting, the manual knee is lowered to 50% video, which means that the white chip on the chart, which normally would rest at 100% video is now one stop under the hottest level, leaving room for real world exposure twice as bright to retain detain in the video. With the DL at less agressive settings that limit is raised slightly to as high as 70% video at 200% Dynamic Level.
One other thing about the Film Rec is that face exposure need not be as high as we’re used to with “video” where faces were normally put at 60-70ire. For the “film” look with Film Rec, we now can safely put the faces at 45-55 ire and even lower in a “low key” scene. This makes the use of Zebras as we’ve used them in the past almost moot and I prefer to conceive of them as a “clip meter” showing me where I’m loosing the detail in the highlights, and setting the face exposure more subjectively or with the wavewform where ever possible to provide scene-to-scene consistancy.
There is no doubt that the Film Rec menu with the four Dynamic Level presets is very powerful once understood and used correctly. Its use like this is not necessarily the origional intention of the Panasonic designers, but is an added feature for those who have no intention of going to film out. It’s usefulness and elegance is so great the Sony has added a similar set of gamma presets to their revised F900R, calling it “Hyper-Gamma” just to further confuse the issue. In that camera they provide four presets, two for WYSIWUG video work and two for filmout, all of which control the highlights and extend the range of the camera to rival what you’d expect with film.
JS
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Does the HDX-900 offer dynamic level adjustments like the Varicam?
Chris Bell
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If I may add some info regarding this.
Varicam as you all know got 3 kinds of fundamental Gamma settings.
1: Video Gamma available in Camera Menu
2: Cine Gamma 1 or AKA – Video REC.
3: Cine Gamma 2 or AKA – Film REC.Some people think Video Gamma is less in Dynamic range but that’s not true and here’s why and I’ll try to explain much simple as I can.
CAM / FILM setting in varicam uses same dynamic range.
what makes different is Video Gamma (in CAM menu) uses conventional video gamma curves. Highlight is compressed by Pre-Knee circuit.In Cine Gamma (FILM Menu)Pre-knee circuit is not being used, instead it is producing much linear luminance responce as possible.
Video Rec as I mentioned in other thread is for what u see what u get application. same as after Telecine process. U can use any HD monitor.
FILM REC is to transfer for film for best result.(Yes u can still use this for video too if you want, more challenge though)
You need Gamma corrector or monitor with built in fuction.
Oh ya your Waveform will be inaccurate too.
you need to go in to HD monitor with Gamma corrector first then waveform.
It’ll be nice if there is WFM with gamma correction.
You’ll need Light meter for proper exposure.
you’ll need to measure exopsure same way you’ve been doing with Film.Herez whats happening.
Lets say u set Dymanic level of 600%.
In Video Gamma – CAM MENU, any highlight signal over 110% to 600% is
compressed to narrow area of 100%~110% VTR D-range signal.In Video Rec – Film Menu, All luminace of 600% signal is compressed evenly and linear to 110% VTR D-Range. And you’ll be able to see compressed 600% signal from VTR as 110% signal.
In Film Rec – Film Menu, pretty much same to VTR D-Range, But different linear compression to make utilization of full 500% to 600% D-range of FILM stocks. This is why Varicam can achieve 11 to 12 stop EV latitude.
This is gonna go circle but IF you shoot in Film Rec, transfer to Film and tarnsfer back to HD, you’ll have same image as Video Rec.(or really close, I guess it depends on Lab).
I hope this helps.
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Chris,
It’s my understanding that the HDX900 has three “Cine Gamma” presets, none as agressive as the Varicams’. I’m still waiting to accomplish a side-by-side comparison.
JS
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Chris,
No it does not have the film rec dynamic range version just cine gamma 1-3 similar to what is found on the SDX-900 except a new one #3 has been added.
The fact of the matter is if you need variable speed, film rec dynamic range, then buy a Varicam such features are why the HDX-900 is not a baby Varicam and a Varicam is not a HDX-900.
Tony Salgado
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Well done,
Bruce now if you want to go even futher try shooting a DSC cam align chart and then some real world subjects where over and under exposure come into play and you will really start to appreciate what film rec versus video rec have to offer.
Test shoots such as these will go along way to help anyone understand when and where either mode would have an major advantage over the other.
The mystery of film rec versus video rec has never actually been a major mystery as Panasonic documented long ago an explanation of film rec in one of their instructional varicam F DVD’s which they gave out.
You just needed to know who to ask for the DVD to receive one.
Tony Salgado
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I actually did do more testing than I mentioned in the original post as I was creating a set up for a shoot tomorrow.
My goal was to create a “look” that will be used for wysiwyg, for tv, not for filmout. My aim was to create a set up that would have slightly more latitude than standard video (without an obvious knee point) but still have the punch (contrast and color saturation) for a finished product. Another consideration was that I wanted to reduce the noise of the camera by giving the CCDs more exposure.
Here’s what I came up with for tomorrow:
Film Rec – dynamic level = 300%
Gain = +3db
Gamma = .62
Black Stretch = -1
ped = 0
black strech level = 9%
color matrix and correction per my taste via DSC chart and real lifeThe result is an image that has a normal gamma for most of the image with a little extra room at the top for additional highlights and an Exposure Index of 400 which makes the image less noisey than Vid Rec at -3Db (which has an exposure index of 640).
And re: the HDX900, if one can set the knee point to 10% in that camera you essentially have Film Rec provided that you can set the knee slope to 500% for maximum lattitude.
In a way the whole “Film Rec” idea is rather confusing as Panasonic, it seems, could just have enabled the knee point to go as low as 10% and accomplished the exact same capability in the camera. As it is Vid Rec with the knee point set at 30% is almost film rec, but with a more obvious “kink” in the density curve at the knee point.
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“And re: the HDX900, if one can set the knee point to 10% in that camera you essentially have Film Rec provided that you can set the knee slope to 500% for maximum lattitude.
Huh? wrong.
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Name: leaknoil
Date: Oct 9, 2006 at 1:21:57 am
Subject: Re: film rec vs vid rec? mystery solved“And re: the HDX900, if one can set the knee point to 10% in that camera you essentially have Film Rec provided that you can set the knee slope to 500% for maximum lattitude.
Huh? wrong.
This was the entire point of the original post in this thread. Hard to believe, but true. Film Rec mode on the varicam is the same as setting the knee point to 10%, and that’s all it does. Period. If you can set the knee point on the HDX900 to 10%, then you have put it in “Film Rec” if you will.
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Thats wrong. Sorry.
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