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Old February 21st, 2008, 01:06 PM   #16
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Historically I've preferred to underexpose video a bit as I hate the look of clipping and feel that skin tones look more filmic when they are in the lower half of the scale. When I shot the test film with the EX1 and Redrock, I made a conscious decision to expose normally, which resulted in a few clipped or close-to clipped areas in the skin tones, leading to loss of saturation and detail there. Ultimately I feel that even if it had resulted in slightly more noise, I would been a bit happier if it had been underexposed a 1/3 to a 1/2 stop. Note that the final version has had a gamma filter applied to crunch the midtones a bit without pushing the highlights.

In a day exterior setting I would definitely underexpose slightly--again, it's a matter of choice but I just don't like the look of clipped highlights, it's a dead giveaway of the medium.
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Old February 21st, 2008, 02:20 PM   #17
 
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Charles...

Thanx for taking the time to provide input. Did you set the zebra to 70% to monitor the skintones? A agree that if ANY part of the image is blown out, it looks pretty bad, especially facial features. I understand that you're saying pushing the exposure to the left allows for more headroom in a run and gun situation, or a situation where time and ability to set up the shot isn't available. From a purely engineering point of view, pushing the exposure to the right, without clipping, puts more "bits" of data on the record media. Clearly, this means a carefully controlled shot, controlled lighting, etc., etc. When is everything that perfectly set up? Not much ;o)

Edit: I'm getting the sense that the engineering performance isn't as important as saving the shot from blown hi-lites.
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Old February 21st, 2008, 02:24 PM   #18
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I'm in the under expose camp. Clipped images look bad no matter what you do to them. Depending on the gamma and knee settings once your luminance gets above 90% it's getting compressed by the knee and the saturation also gets reduced. If you look at the majority of the EX1 gamma curves you will see that like most video cameras they are deigned to progressively roll off highlights, compressing the top end of the luma curve. So pushing your image too far up the curve will result in a loss of contrast. You should be aiming to put the majority of you picture information in the center of the luma curve with highlights rolling off at the top of the curve. If you need more range in the darks then bring up the black stretch.
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Old February 21st, 2008, 04:29 PM   #19
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Interesting.

In digital stills using CMOS and raw images underexposing is better than overexposing. Once its over exposed the data is lost whereas with underexposing the data is recoverable.
That's the same approach when I used to shoot transparency film. It was always safer to under expose slightly because blown highlights were gone forever. I take the same approach today shooting video.
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Old February 21st, 2008, 04:37 PM   #20
 
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Dean...

I would refer you to this article my Michael Reichmann at The Luminous Landscape

http://www.luminous-landscape.com/tu...se-right.shtml

Now, CMOS may be different than CCD, I don't really know. But digital is certainly not the same technique as celluloid.
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Old February 21st, 2008, 05:10 PM   #21
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Interesting thread..

I see both sides to this question.

It's really down to matching the best gamma curve for a given situation.
Having 3 to 4 picture profiles set with different gamma curves is a must.

I have found that exposing the EX1 a bit to hot does tend to wash the image out.
My JVC HD100 would of reacted different under those same conditions offering less range.

This additional latitude allows you to find the sweet spot between max exposure and blacks.

On thing for sure, the EX1 LCD really gives you a good idea on your overall image exposure. The EX1 LCD was quite the surprise.
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Old February 21st, 2008, 05:20 PM   #22
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Interesting thread..

I see both sides to this question.

It's really down to matching the best gamma curve for a given situation.
Having 3 to 4 picture profiles set with different gamma curves is a must.

I have found that exposing the EX1 a bit to hot does tend to wash the image out.
My JVC HD100 would of reacted different under those same conditions offering less range.

This additional latitude allows you to find the sweet spot between max exposure and blacks.

On thing for sure, the EX1 LCD really gives you a good idea on your overall image exposure. The EX1 LCD was quite the surprise.
Exactly. I believe I said I was judging most exposure by looking at the LCD and forgetting Zebras and Histogram, and that was giving me an exposure of about half a stop down. Maybe a good idea to set the Zebra to 95 as Doug Jensen recommends?
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Old February 21st, 2008, 05:38 PM   #23
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I hear you there.

Chances are if you like what you see on the LCD, it's probably close.

I believe Bill is on the correct path by working out what the EX1 luma values mean to "real" image quality and how he deals with them with his NLE.

I've been using Vegas for years. It will be hard to walk away, but I can't count the amount of times of stopped and thought "WTF is with this?...".

Glenn has definately helped set some of this madness straight.
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Old February 21st, 2008, 05:44 PM   #24
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Bill...

Thanks for the link. Valuable info.

The process Luminous Landscape is describing is a bit beyond what can be achieved with 8-bit digital video -- at least digital video that doesn't include Red One.

LL is making use of "raw" files which have more data in the highlights than might be shown in an 8-bit display conversion. Raw formats, in fact, are supposed to contain every last bit of data coming off the imager. So the image histogram can be pushed a bit more toward that direction without losing highlights. Makes a lot of sense.

But with conventional 8-bit digital video the option of recovering highlight info from a "raw" file isn't available because there's no brightness data beyond 255. I sure wish there were! And, if you look at a histogram in an EX1 it might tell you there's a lot more headroom to the right, but it's not really showing you what all the chroma channels are doing. One of the channels might actually be maxed out and clipping long before the EX1's histogram gets near the danger zone. The only way to tell is by looking at the image in the viewfinder and seeing if there's any telltale color shifts or bleaching in important quarter tones and highlights.

Maybe there's a way to set up the EX1's histogram to provide accurate display of all three chroma channels. That would be very helpful.

My underexposure is usually slight. Just enough to ensure skin tones don't burn out. As Charles Papert mentioned, it's one of the worst things that can be done to digital video. I usually make a very quick assessment of what are the most important elements in the viewfinder and adjust my aperature accordingly (I do mostly run-and-gun work on a fishing show).

And there's that age-old tradeoff of how far you can go to protect highlights. Some might try to protect bright skies but for me that's sometimes a battle that can't be won as it would certainly force the lower tones to be opened up excessively and increase the noise level horrendously.
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Old February 21st, 2008, 05:44 PM   #25
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Originally Posted by Steven Thomas View Post
I hear you there.

Chances are if you like what you see on the LCD, it's probably close.

I believe Bill is on the correct path by working out what the EX1 luma values mean to "real" image quality and how he deals with them with his NLE.

I've been using Vegas for years. It will be hard to walk away, but I can't count the amount of times of stopped and thought "WTF is with this?...".

Glenn has definately helped set some of this madness straight.
If to use 32-bit color one has to apply levels to everything to be able to use the histograms that's just plain stupid. These things need be aired on the Vegas forum however and not too much here as a lot is wasted. I will experiment tonight with exposure and see how close I can get to clipping and give the look I like. The problem I see with pushing it is that its make the footage look more like video and we just spent 7g on a camera to get away from that. Of course I suppose if you had magic bullet then the max info might be right.
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Old February 21st, 2008, 05:53 PM   #26
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Different meanings...

In my post I meant over exposing to mean blown hi-lights or 'clipping'. To me that is over exposing. I may or may not correct in my definitions but the fact remains that if a shot has blown hi-lights, clipping or whatever term you use: once its gone its gone.

Where one chooses to have the peaks on your histogram is up to you and the subject. Michael Reichmann is probably right - the guy seriously knows his stuff.

I shoot 99% the ocean and I like to see the shadows etc in broken waves hence the tendancy to slightly under expose.
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Old February 21st, 2008, 06:31 PM   #27
 
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Dean...

You make some very valid points, re RAW vs. 8-bit digital. You and Charles have me convinced. I need to back off my thoughts on pushing the histogram to the right.
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Old February 21st, 2008, 07:27 PM   #28
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Charles...

Thanx for taking the time to provide input. Did you set the zebra to 70% to monitor the skintones?
70% is way hot for my tastes on skintones. I like to see them top at 60 IRE, and generally hover closer to 50. I don't make it an exact science however, I use a waveform to keep myself honest but I rely primarily on a properly calibrated monitor.

If you were to look at this trailer, I was driving the exposures way down (preferably with some highlights somewhere in the frame to maintain a bit of contrast). A few times I managed to burn myself when we were working quickly and I couldn't get to the monitor (don't get me started on having to operate and DP on HD shows) but overall the stuff looks exactly like I wanted to.
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Old February 21st, 2008, 08:12 PM   #29
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70% is way hot for my tastes on skintones.
Charles, so are you saying the brightest highlights from carcasion skin to show zebras at 60?
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Old February 21st, 2008, 08:19 PM   #30
 
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Charles...

very nice. and throughout all variations of lighting. thanx Rather a "dark" film, speaking about the subject.
someone spent some time setting the lighting up on those scenes, and it was captured beautifully.
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