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Sony HVR-Z1 / HDR-FX1
Pro and consumer versions of this Sony 3-CCD HDV camcorder.

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Old August 24th, 2006, 08:49 AM   #16
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You have a limited amount of contrast range to work with so if you expose for skin tones and other stuff blows out, you must re-frame or re-light the scene if possible to avoid that. You might be able to use a graduated ND on the front if it's a bright sky against horizon scenario. If you don't have skin tones, some say concrete should also be around 70%. Always best to under-expose a little cause you can recover some shadow detail in post, but blown highlights are gone and there's no getting them back.

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Old August 24th, 2006, 10:32 AM   #17
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What IRE is light spills from everywhere

Originally Posted by Tom Tanquary
Hi All, I'm new to this forum - having just bought a Z1 - and this thread caught my interest right off.

But many times the scene is wider than a single face and other exposure factors may take over. Wide shots of people directly lit by the sun may have their faces at more than 70% to acchieve an overall good exposure. A washed out face in this case is hardly noticeable and that screen area is too small for much detail anyway. It's at this point that the dynamic range of the camera comes into play. Which is more important: the shadows or the highlights?

Setting zebras at 100 has never made sense to me. 100 is pure white, no detail. So what? There are so many things in a scene that will be over-exposed long before you get to 100. The white paper is a good example. At 90% that paper is blooming big time, at 100 it's gone. Most all of your exposure decisions are made well under the 100% video level. Which is why professional videographers have always used 70 as a benchmark. Most all surfaces in the upper third of reflective quality (reflect the most light) will start to loose detail above 70%. Whether it's human skin, a white piece of paper, or a sun lit concrete wall, those zebras let you know how much detail you'll get at that iris.
I have a question as well...
I currently shoot with VX2100's and PD170's and had an issue while uding zebras at a wedding I shot 2 weeks ago.

The reception was midday to sunset and into the evening. The ballroom has glass pretty much going 3/4 of the way around it. So light is spilling in from everywhere.

I shot footage at 70 IRE for the entire day, and move around quite often handheld (mainly wide and medium shots, with some closeups), so sometimes I had light at my back (great scenerio), but most of the time I had light spilling in from all sides.

I made sure I was slightly seeing some small zebra, on faces I was shooting at 70IRE. However after I looked at much of the footage, most of the whites and any faces that had light shinning on their faces were blown out (not soft looking yellow gold like it should have).

My wife was manning a second camera on a stationary tripod, and mostly had light at her back, so her exposure was much better than mine with faces that had nice golden highlight for sun exposed faces.

So my question is this...
In my instance where I have no control over light spillage, ould it have been best for me to shoot at 100 IRE and adjust accordingly.
Or shoot at 70 IRE with ND filter on and make sure that that I don't have any zebra on faces.

I have a shoot this Saturday at the same venue, and would like to find a solution beforehand.

Last edited by Michael Liebergot; August 24th, 2006 at 11:42 AM.
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Old August 25th, 2006, 04:22 PM   #18
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There is no "magic bullet" to all this, Brendan, it takes time to learn and experience to add a bit of voodoo to the mix to hopefully come out with a proper exposure.

Many news shooters use 100% (and often 90% zebras to keep from overexposing highlight areas, because they have been threatened with excommunication by some engineer at their station. This will keep them from burning out the hot sky, but may leave the face in the foreground underexposed, and usually you want the face properly exposed rather than the sky. Why you are choosing to use 90% zebras on a face I have no idea; this should lead to consistently overexposed flesh tones. Are you familiar with what you are viewing on the waveform display? However, let me say, if you set your zebras to 90%, and are getting consistently good results, who am I to argue?

"I put the footage in fcp and the skin tones were fairly good, but the level for many shots was over 100"
What was over 100%? A light in the background? A window to the outside? Was it something of value, or do just not want anything over 100%? Ever watch live music shows on tv, like "The Grammy Awards," or "The American Music Awards"? When those bright lights hit the camera lens, do you think they go over 100%? You bet they do, but they get clipped in the transmission, so there is no harm done. (I'm simplifying here a bit) So if you have a window in the background that is over 100%, but you like the way the picture looks, go ahead and shoot it, because you camera will clip it to an acceptable level, but you will lose the detail in that area, just as you see in your monitor. A waveform monitor is great, but if you spend all your time fiddling with the waveform and an outboard video monitor, you are not going to be getting much shooting done. This may be OK if you are shooting your movie, and you want everything as close to perfect as possible, but if you are under time constraints, your will be in the deep muddy.

You need to identify contrast problems before you even turn on the camera. For instance, I am writing this in my studio on my Cinema display monitor, in a room I keep at low light levels for my post production work. (Not dark, but dim light) If I wanted to shoot my monitor on camera, as well as the background wall, I need to have a reasonable range of contrast between foreground and background. I can identify a potential problem by using my eyes and squinting at the scene. By squinting, I lower the range of contrast to something closer to what the camera sees, and what I discover by squinting, is that the monitor looks great, but my background wall is almost black, and there is very little detail. This indicates a problem. Now reverse the situation.

You are outside shooting a stand-up piece with an on-camera host. She wants to stand facing the camera with her back to the sun (good), but in a position where you will see hot sky behind her. You view her and the sky, and when you squint, the sky cools down nicely, but her face goes black. Problem. You either need to add fill to her face, or cool off the sky, or move to another location. Or, you say "to hell with the sky" and expose for her face. If you have your zebras set to 100%, you will pull down the exposure until you would have only a hint of zebras in the sky, but I promise you, now her face will be underexposed.

The point is, you can identify the problem areas by squinting; you don't need a camera or a waveform to tell you that you have a problem. Don't take my word for it, just give it a try. This is a combination of learning and experience. Takes time. And continue reading and researching all you can find. Good luck.

Wayne Orr, SOC
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Old August 26th, 2006, 01:28 AM   #19
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Originally Posted by Michael Liebergot
In my instance where I have no control over light spillage, ould it have been best for me to shoot at 100 IRE and adjust accordingly.
Or shoot at 70 IRE with ND filter on and make sure that that I don't have any zebra on faces.
Michael, the posts above this one talk about this quite well. IRE is just a measurement tool. Exposure is a tougher question. In the situation you describe, contrast can have a lot of play in how you exposed the shot. A normally exposed face up against a 100IRE+ background just won't look the same as it does against a 40IRE level background. Again, 100 IRE just means that is where the video looses all detail, 110 IRE looks exactly the same as 100 IRE, and the same area at 95% is pretty much the same - way over-exposed. If your faces don't have any detail when their skin tone levels are just under 70 IRE, you might be having another type of problem.

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