over exposure issue

J

jay_broken_doll

New member
hi
I recently bought a dvx200 a couple of weeks ago and have been playing and experimenting with it. I am noticing a very worrying issue....
As an example of this, I shot some footage of my wife in the garden on a sunny day, scn 6, zebras set to 70%, using varying nd filter and iris settings.
I was very careful to just have zebras appear in only small areas.
The picture is a screenshot of what I see when footage is in my editor (sony vegas pro13).
The scopes are showing what I would expect to see baring in mind how I shot the footage. However, the highlights on the shoulder, neck and knee are completely clipped.
Any thoughts or suggestions would be welcomed. Thank you.
sian.jpg
 
I think this is a situation where you have to trust the monitor a little more than you might normally. With the DVX00 just because you don't see the zebras doesn't always mean that your highlights aren't going to be overexposed. The next time you are practicing, once you have cleared your zebras, using the monitor or EVF, look closely at your highlights. I have found that the monitor or EVF are pretty good at displaying any clipped levels in the skin tones even if the zebras aren't showing up. It seems like there is not very much room between properly exposed and over exposed skin tones.

I mainly have been using the GH4 still like scene which I believe does a very good job at displaying natural colors. For a while I had my zebras set for 70 percent and trusting the zebras exclusively gave me slightly underexposed results. A guy that I work with that's been in the business for over 40 years told me to set my zebras to 80%. When I did that my skin tones looked much much better but I was getting just what you are showing in your example. On a shoot the other day that I could re-shoot if necessary I opened up until the zebras just started showing and then I backed off until they went away. I then scanned over the skin tones and in most cases I had to stop down just a little more until some slight over exposure was reduced. The footage turned out great!

I think if you do a playback in camera of that sample above, chances are you will see the same hot skin tones during playback which means that you would have seen them during shooting. Never trust zebras or your waveform 100%. These are all tools that help us get the best image that we can but there is something to be said for trusting your eyes also. In nearly every case that I thought something didn't look right when trusting the waveform, zebra or even a manual white balance, the end results during playback appeared poorly also.

A few weeks ago I did a manual white balance three times because I just didn't like what I was seeing on the monitor. For whatever reason the camera just wasn't balancing like I was expecting to see. I went into variable white balance and adjusted the k setting to something that looked more like what I was expecting to see. The end results were perfect. Had I gone with what the manual white balance was showing me, I'm almost certain that I would not have been happy. This was one of the only times that manual white balance wasn't doing a good job for me.

If you look back at some of my previous posts I've said, "never trust your monitor". With the DVX200 I think I need to start saying "know when to trust your monitor".
 
I have found exactly the same thing. Seems that with zebras set to 70, the DVX exposes a bit hot on skin in SCN6. Generally I set zebras at 70 and as soon as they appear then back off the exposure just a tad until they disappear. Skin then seems to be exposed "just right". As an FYI this differs from the GH4 where setting the zebras at 70 seems to give good skin exposure (in CineD mode). The SCN6 on the DVX seems similar to CineD on the GH4 with better dynamic range than SCN4 ("GH4 still like scene" which seems closer to Natural on GH4). I prefer SCN6 to SCN4 (which everyone else seems to like!) as 4 crushes blacks a touch too much for my tastes...
 
I am curious to know what exactly is SCN6? Is it the same configuration as when the camera was first introduced? Surely this can't be correct. After all the firmware updates, it was my understanding that there is only one Scene file, SCN4, which is tuned properly with the latest firmware. The others are outdated, right or wrong?
 
greytail said:
I am curious to know what exactly is SCN6? Is it the same configuration as when the camera was first introduced? Surely this can't be correct. After all the firmware updates, it was my understanding that there is only one Scene file, SCN4, which is tuned properly with the latest firmware. The others are outdated, right or wrong?
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While I don't have the exact answer I have a feeling that firmware upgrade made the factory scenes "usable" but I think the only scene that was put under the microscope after the upgrade was the GH4 Sill Like scene.

If I use 70% zebras on the GH4 Still Like scene it's way under exposed when I bring up the zebras and then back off the iris until they go away. 80% is a little too hot. Being that has been the only scene that I have been using I may adjust the zerbras to 75% and see if my procedure works better.

From this thread it appears as though zebras aren't quite reliable from scene to scene and using one number for all scenes may not be the best method. It may be that we have to find the right zebra percentage for the scene that we are using.
 
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The zebras should have been all over those skin highlights. Back off the exposure until there are NO zebras anywhere on the skin. You don't want all the skin showing zebras, you want only the absolute hottest bits showing them.
 
Thank you all so much for taking time to reply and give advice.

Razz16mm I have been using dslr's for the last 10 years canon's and more recently a7s. I have always managed to push the highlights using the rgb parade without getting any blown-out highlights (to my eyes anyway) and was surprised to see the scope showing what it did considering the amount of visible clipping.

greytail I understood that with the new firmware updates that the current factory scenes were all useable and that the scene files created by Barry_Green were now obselete as they addressed the issues with the old scene files from previous firmware - is this correct Barry_Green?

I will have a look at the knee setting - I used the default scn6 settings, (I do remember reading something about the knee and skintones) Mike Harvey

I will definitely approach exposure a lot more cautiously mapper65, Barry_Green, UWNick.


Going to be putting many more hours in, looking forward to enjoying this camera!
thanks again all

jay


 
I thought I had replied to this but don't see my post. I'll try again. I set my Zebra to 100. I expose as hot as I can WITHOUT seeing any Zebra on skin. If I see Zebra elsewhere, then I make judgements about whether I want to iris down more. The 100 Zebra setting is the only way I know for sure if any skin is over exposed. The 70 setting tells me what is optimum for a given area of skin but does not warn me about possible overexposure of highlights.
 
David_ said:
I thought I had replied to this but don't see my post. I'll try again. I set my Zebra to 100. I expose as hot as I can WITHOUT seeing any Zebra on skin. If I see Zebra elsewhere, then I make judgements about whether I want to iris down more. The 100 Zebra setting is the only way I know for sure if any skin is over exposed. The 70 setting tells me what is optimum for a given area of skin but does not warn me about possible overexposure of highlights.
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I typically use 70%-80% zebra and then back off when I see the zebras until they go away. Then I'll press the zebra button again to set it at 100% and then look over the entire scene. You can do the same thing with skin tones. Kind of a quick double check. With skin tones if you don't see them at 80% your not going to see them at 100% but it helps you make that decision of closing down another stop if necessary should something else in the scene be blown out.
 
David_ said:
I thought I had replied to this but don't see my post. I'll try again. I set my Zebra to 100. I expose as hot as I can WITHOUT seeing any Zebra on skin. If I see Zebra elsewhere, then I make judgements about whether I want to iris down more. The 100 Zebra setting is the only way I know for sure if any skin is over exposed. The 70 setting tells me what is optimum for a given area of skin but does not warn me about possible overexposure of highlights.
Click to expand...

This method will guarantee nasty blown out skin highlights. Guaranteed. You cannot let skin go to 100 IRE; you really shouldn't let it go to even 85. Any higher than that and you will likely get clipping in the red channel.

Set your zebras on 70. 70 is not the average, 70 is the MAX. 75 at most. And then don't let any zebras show anywhere on the skin. You should only ever see the tiniest trickle of zebras showing up on the hottest, brightest skin highlights, at 75. You should try your best to never let them get any brighter. 100 is right out.

100 doesn't mean that nothing is clipping. It only means that the average brightness level isn't clipping, but individual color channels most certainly may be clipping at 100! The IRE level is made from basically 59% green, 30% red, and 11% blue. Skin is more red than green or blue, so it represents a disproportionate amount of brightness. If you filmed something that was pure red, with no green or blue at all, and you fully saturated the red channel so that your RGB channels were 255/0/0, you'd have an IRE level of only 30. You'd have 30% of 100% R, plus 59% of 0 G, plus 11% of 0 B. That adds up to just 30 IRE, even though the red channel is fully saturated to the point of clipping.

That's how IRE works. So when you go filming something that is disproportionately red, the odds are that the red channel will clip before the IRE level gets very high. On an AF100 in the normal gammas, the red channel in skin starts clipping at 82 IRE. You can't let any skin element get that bright or you risk getting ugly color-shifted highlights in the overexposed areas.

The newest firmwares for the DVX200 have really cleaned up the color shifts, but nothing changes the fundamental r/g/b situation. Keep your skin highlights below 85, ideally below 75, for best results.
100
 
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Barry_Green said:
This method will guarantee nasty blown out skin highlights. Guaranteed. You cannot let skin go to 100 IRE; you really shouldn't let it go to even 85. Any higher than that and you will likely get clipping in the red channel.

Set your zebras on 70. 70 is not the average, 70 is the MAX. 75 at most. And then don't let any zebras show anywhere on the skin. You should only ever see the tiniest trickle of zebras showing up on the hottest, brightest skin highlights, at 75. You should try your best to never let them get any brighter. 100 is right out.

100 doesn't mean that nothing is clipping. It only means that the average brightness level isn't clipping, but individual color channels most certainly may be clipping at 100! The IRE level is made from basically 59% green, 30% red, and 11% blue. Skin is more red than green or blue, so it represents a disproportionate amount of brightness. If you filmed something that was pure red, with no green or blue at all, and you fully saturated the red channel so that your RGB channels were 255/0/0, you'd have an IRE level of only 30. You'd have 30% of 100% R, plus 59% of 0 G, plus 11% of 0 B. That adds up to just 30 IRE, even though the red channel is fully saturated to the point of clipping.

That's how IRE works. So when you go filming something that is disproportionately red, the odds are that the red channel will clip before the IRE level gets very high. On an AF100 in the normal gammas, the red channel in skin starts clipping at 82 IRE. You can't let any skin element get that bright or you risk getting ugly color-shifted highlights in the overexposed areas.

The newest firmwares for the DVX200 have really cleaned up the color shifts, but nothing changes the fundamental r/g/b situation. Keep your skin highlights below 85, ideally below 75, for best results.
100
Click to expand...


This makes a lot of sense. I have to really watch for chroma clipping when I grade D16 footage. The camera's color gamut falls just shy of the REC2020 boundary, way beyond REC709. I have to desaturate 20-30% to get into normal REC709 range.
 
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