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Old October 7th, 2006, 06:30 PM   #1
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Better to expose for low lights or highlights?

In terms of aquiring the best possible visual data for manipulation later in post, is it better to lean towards nailing the highlights (underexposing) or getting the most detail in the lowlights (overexposing)?

In other words-- which is more easily "rescued" in post (without introducing too much noise, artifacts, or other garbage): underexposed dark areas or overexposed light areas? I have a HD100 so I'm asking specifically about that camera.

I've had people (not on this board) advise me both ways ("Shoot for the WHITES!" "No, no, NO!!! Make sure your BLACKS are perfectly exposed and the whites can be brought in later in post!" etc. etc.) Any help for this HD100 newbie would be much appreciated.

My philosophy on video acquisition is similar to what I've understood Paolo to say: just try to get the truest image with the most data and leave the fancy/crazy effects for post.

On this same subject-- I'm experimenting with a camera set-up that I call Xtreme Latitude. Basically I use Paolos TC3 but then I go to black stretch 3 and set the knee to 80%. Is that really the way to get the most out of your blacks and your whites at the same time? If it is, why wouldn't everyone use that? What is the trade off? What am I losing?

Thanks, you guys, for your help yet again.

I've been hard at work learning my new FCP and HD100 setup--right now I need a lot of help but I'm learning fairly fast and I really want to pay back the knowlege that I'm borrowing now by helping out the newbies down the line in a year or so once I've really learned this stuff.

This board is simply invaluable-- no other word for it.
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Old October 7th, 2006, 06:33 PM   #2
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Clipped highlights can never be brought back.

Blacks that are too low can be brought back a little, with consequences in noise level.

I always play close attention to highlights when shooting video. Look at my reel to see you where that gets you.
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Old October 7th, 2006, 07:29 PM   #3
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Blown out highlights are far more objectionable (and harder to fix) than crushed blacks. That said, I tend to expose to get midtones, especially faces, where they should be. I tend to use gamma a bit to fudge the midtones into the zone I want them if some highlights or blacks are killing me, rather than using knee or black stretch. Knee and black stretch tend to look a bit unnatural to me, while gamma looks a bit smoother.
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Old October 7th, 2006, 07:36 PM   #4
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you will want to slightly underexpose...not much though.
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Old October 7th, 2006, 09:11 PM   #5
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Here's a method I like to use that's been very good to my footage.

Set your Zebra menu for 60-70% and then expose your shot so the zebra just creeps onto faces. Everything else will fall into place. Try it...
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Old October 8th, 2006, 02:01 AM   #6
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I agree, underexpose, but just a little; you can't get detail back in blown highlights, and with HDV you can't get much back out of blacks. If you are shooting one of the more robust HD formats, like HDCam, or DVCProHD, you can get away with as much as 2 stops under (to protect detail in the highlights), and still retrieve the detail in the blacks in post. But not HDV.

Also, black stretch can introduce noise into the blacks, and a low knee setting, while giving you a stop or so more dynamic range, can cause you to loose detail, and in some cases cause color changes, in the highlights.

I like Stephen's 60-70 zebra suggestion; it will give you a good mid-range exposure. Remember it's all about creative decisions, especially when you can't use lighting to correct for the limited dynamic range of these cameras. (I'ts true of most all of them).

Good Luck,

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Old October 8th, 2006, 03:28 AM   #7
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Quote:
Originally Posted by Stephen L. Noe
Here's a method I like to use that's been very good to my footage.

Set your Zebra menu for 60-70% and then expose your shot so the zebra just creeps onto faces. Everything else will fall into place. Try it...
... Depending on the skin tone. This works for normal caucasion faces (but not albinos), though can be tricky with Kidman/Blanchett faces.

Dark skin tones and mixed skin tone ranges call for different approaches.

So here's a question, suppose we have three faces filling the screen. One is caucasion, one is dark african, one is a skin tone have way between the other two. In a correctly exposed frame (with neutral background in the midranged), where on the waveform monitor should each of the three skin tones fall? (What number, e.g. is caucasion 70?, etc.)

In some situations the issue can be helped with lighting techniques, but what about in the documentary. How do you keep detail, life, expression and character in the dark faces while doing the same for the light faces?
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Old October 8th, 2006, 12:46 PM   #8
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We're just looking for rules of thumb here, not a contingency for every possible situation. Obviously every shot requires slightly different "rules" for exposure, but that doesn't keep you from using some basic guidelines to get you in the ballpark.

For an unusual shot with difficult exposure requirements I just throw the rules out the window and concentrate on making it look good. That's just a judgement call, finding the best possible balance. That's why I tend to focus more on the midtones when setting exposure, if I get the midtones right the highlights and shadows usually just fall into place. Even if it's too contrasty for that to work completely I've achieved a good balance between blown whites and crushed blacks that works anyway, and favoring one would kill the other too much.

If you've got an albino standing next to a black person, nothing in the world is going to make it look perfect, but if you work it right you can achieve a balance that's acceptable for both subjects.
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Old October 8th, 2006, 12:58 PM   #9
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I agree with everyone here that it's better to underexpose (slightly) rather than overexpose.

Here's a different approach I use for setting zebras. I put them at 100% and open the iris until the widest, brightest areas begin to show stripes, then I back it off a little so the wide areas are zebra-free and only the tiniest highlights (like reflections, light bulbs, etc.) are striped. This essentially means you are right below the point of overexposure, regardless of the subject.
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Old October 8th, 2006, 01:02 PM   #10
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Quote:
Originally Posted by Earl Thurston
I agree with everyone here that it's better to underexpose (slightly) rather than overexpose.

Here's a different approach I use for setting zebras. I put them at 100% and open the iris until the widest, brightest areas begin to show stripes, then I back it off a little so the wide areas are zebra-free and only the tiniest highlights (like reflections, light bulbs, etc.) are striped. This essentially means you are right below the point of overexposure, regardless of the subject.
With this method, make sure you bring up the light levels on your subjects and in your shadows. A light meter would be helpful for this method, it will tend to underexpose heavily and you will crush your black beyond recovery.
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Old October 8th, 2006, 01:22 PM   #11
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Originally Posted by Cole McDonald
...it will tend to underexpose heavily and you will crush your black beyond recovery.
I haven't had any problems like that so far. Fortunately the HD100 picks up the shadows quite well.

The only times I've underexposed too far was when it was directly my fault -- either I wasn't paying attention or didn't follow my own technique. (Rushing, winging-it, etc.)

To clarify, you only want to back off very slightly, so the zebras in only the widest areas just disappear. (Even small patches, like clouds, etc. are okay to show zebra.)

We should also add, there is no one technique that works all the time. Mine is not the right one to use if your subject is in front of a bright window, for example. In that case, the 70%-faces technique is probably better.
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Old October 8th, 2006, 01:56 PM   #12
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Of course we're talking about shooting documentary style. I first tried Earl's style of shooting which is the way I shot with Panasonic. Setting the highest highlight on the 100% zebra. Then I found my skin tones were way off so I decided to use the skin tones as my reference with 60-70% zebra and suddenly everything came in without me worrying about them.

Try it, Zebra 60-70% on the skin.

About skin color, use your best judgement. If I have a variety of skin tones, I select a person as the reference that represents the median tone.
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Old October 8th, 2006, 02:54 PM   #13
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Quote:
Originally Posted by Earl Thurston
I haven't had any problems like that so far. Fortunately the HD100 picks up the shadows quite well.

The only times I've underexposed too far was when it was directly my fault -- either I wasn't paying attention or didn't follow my own technique. (Rushing, winging-it, etc.)

To clarify, you only want to back off very slightly, so the zebras in only the widest areas just disappear. (Even small patches, like clouds, etc. are okay to show zebra.)

We should also add, there is no one technique that works all the time. Mine is not the right one to use if your subject is in front of a bright window, for example. In that case, the 70%-faces technique is probably better.
I do expose this way (at 90%), but I make sure to bring the brightness of the subjects up so they don't fall into shadowand the shadows so they don't fall black...with a short latitude (dv/hdv) we have to make sure that we aren't pushing our blacks too dark or the highlights too bright :) If we work within the limitations of the format, we can make pictures that look like they aren't as videoey (is that a word?).
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Old October 8th, 2006, 04:03 PM   #14
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The only times I've underexposed too far was when it was directly my fault -- either I wasn't paying attention or didn't follow my own technique. (Rushing, winging-it, etc.)
You've made mistakes (winging it etc)? Glad somebody else has when first starting out (and you quickly learn from these!).

As a rule of thumb, would it be best to leave at 70% or ignore completely? I'm reading some who do not use zebra at all and others who swear by 70% or 100%?
BTW - I was reading about zebra on this forum (not the JVC section) and some people are using -3db outdoors - I can't seem to be able to do this with the HD100 - possible?
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Old October 8th, 2006, 05:34 PM   #15
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Thanks for all your answers. If I could narrow it down just a bit, I guess what I was specifically asking was not so much about exposure reading techniques in the field (although there were some great suggestions), but rather-- which is easier to "rescue" in post (in an HD100 HDV 24 or 30P to FCP workflow); underexposed black, or overexposed white? In other words-- if you have to goof up, which way should you goof?

Some of you said it's better to slightly underexpose. I would tend to agree. But how does the equation change once you start using extreme settings? (suppose you set your black stretch at 3 and your knee at 80%)

Am I really getting more information in BOTH the lowlights AND the highlights with black stretch 3 and 80% knee? (seems like getting something for nothing--a "free lunch") Or am I losing something (like the mids, maybe?), and I should pull either or both settings in a little? And when using such an extreme setting should I still underexpose a bit?
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