Piotr...

Your image41 is not the same one that I saw that was very overexposed. Image41 definitely looks very strange...actually, it looks like the white balance settings are off.


Bill,

The image41 comes from the very same few seconds of shooting; it's actually a couple of frames away from those previously posted. I made the reservation about WB not being right in my original post.

The only difference between image41 and the previous four is that this one has been grabbed from an 8bit Vegas project, while the previous ones - from a one with 32bit video setting.

Do you agree now that it's not the question of overexposing, but of how being on the verge of overexposing is being handled by the EX1? I guess it'd be very important for all of us users if all the interested parties came to a conclusion, as it could be passed on to Sony as an important issue for the future firmware release.

Piotr...

when you switched to 32-bit processing, did you check the Vegas WFM for clipping? Ordinarily, when I switch between 8-bit and 32-bit, I need to apply a correction, depending on the codec type. One can't arbitrarily turn on 32 bit without adjusting levels.

For example, .mxf files, I can drop a native .mxf file on the timeline in 8-bit and the levels look right, black is at IRE16 and white is at IRE235. If I switch to 32 bit, suddenly black is at 0(-8% IRE) and white is at 255 (108% IRE) These values are techncally blown out if you're looking at a studio RGB monitor. A Level correction converting computer RGB to studio RGB is needed to correct the images.

Bill,

Yes I am aware of how mfx decodes in 8bit vs 32bit Vegas projects, and belive me this is not the source of the problem. With 32bit, applying the Computer RGB to Studio RGB convertion is barely visible; in 8bit the difference is more apparent (right half of the grab below is converted to Studio RGB; while the superwhites are remapped, the blue "shadow" behind the trees is still there).

But believe me, Vegas is not the factor; in fact I only use it take grabs from timeline. The problem is clearly visible by just playing the file with WMP.

Guess I'm with Steve Thomas. Other than my initial foray into STD curves, which I abandoned very quickly, I don't use them much. I'll look at this some more to see if I can make my cam malfunction like this. In CINE mode, all the manual knee adjustments are disabled. In STD mode, auto knee is turned on. I'm not sure how this functions. Could it be that the camera processor pushed the knee out to an irrational setting to cause what you're seeing?

I must say that I just finished shooting a 240 sec short ...lots of gray skies, snow everywhere, a few patches of blue here and there. Difficult exposure situation for the camera meter with all that snow. Footage turned out stunningly. Lots of detail....no mosquito noise...none. I'm so happy with this camera.

http://www.dvinfo.net/gallery/showimage.php?i=848&c=2
http://www.dvinfo.net/gallery/showimage.php?i=849&c=2
http://www.dvinfo.net/gallery/showimage.php?i=850&c=2

So, after all, even Bill has agreed that the camera is malfunctioning.

I'd appreciate it very much indeed if anyone recreated this with his own unit, and put the result in this thread. Only then will I know for sure if it's only my camera that needs servicing, or a general firmware flaw that can hopefully be ironed out by a firmware update.

Yes, I 'll get around to it.
Bill, that last shot looks great man!
http://www.dvinfo.net/gallery/showimage.php?i=850&c=2

Thanx, Steve.
I used to live in Tempe. I ventured south to CG on many occasions.
Spring training is coming up soon, isn't it?

If the white areas in the sky are a result of being blown out and would have been blue. If the iris was closed a bit more. If the areas around the tree branches twigs etc was blocking light then those areas could possibly have a blue aura? It sounds logical to me.

The colour temperature is set wrong and is too blue, adding to this. I wonder how the image would look taken in camera at the correct temp? I corrected the colour temperature in AE and still there is a blue cast around the trees but also some areas of white. The problem is not uniform. I dont think the camera is at fault at this point. Its going to be interesting to follow this.

As we all know, you either expose for the sky and the foreground is underexposed, or expose for the foreground and blow out the sky. As to why this is happening in the camera, I do not own one so cannot say. But if you want your cake and to eat it too, you can always use a grad filter and you would be golden.

It is severly overexposed. The sky is clipped. One of the somewhat more expensive cameras that I use used to clip to purple. Wasn't really seen as a big issue although it got fixed. The Redone clips to pink if pushed.

The EX1 is more of a digital cinema camera than a video camera. As has been said by many, if you don't know what you're doing with it you can very easily get yourself into an ocean of grief. If you really want to tweak things then you're either going to have to learn a lot or have a monitor hooked up off the HD-SDI port. Perferably one with scopes built in as well. From what I've seen so far the composite SD port does not give you the true picture of what the camera is recording.

And yes, I know a few people who've been using all manner of video cameras for decades. They're having a hard time understanding how cameras such as the EX1 work and how to wrestle the best possible image out of them. This camera does go to 11, use it with caution.

Have a look at the histogram for the blue channel, look pretty badly clipped to me.

Just to jump in to the conversation...

Here's a grab of a test shoot I did yesterday.

I'm a little dark inside (the mantle) and totally blown out...especially in the window picture right.

I could have sworn the stuff I've shot with my XL-2 (my old cam) wouldn't have been so drastic...but this is a totally different camera. There are a lot more examples where there are these drastic brightness conditions, but also a lot of stuff that just blew me away with how stunning it was...and this was shooting 720p.

I love the camera so far, just think it will take some time for us to get to know each other!

I'm chalking this up to operator error since it was my first day out with the camera in a practical situation and wasn't equipped with filters.

After having read Bob's post, Piotr, I know you were using Bill's original TC setting which uses a standard gamma. Did you happen to try turning off the profiles and use the camera's default standard video settings?

That would of been interesting. Bill, I know you took great care in setting up the color channels. Maybe its possible that things are a bit hot with these setting which may drive the colors to clipping a bit early, which may be causing what Piotr has been concentrating on. But on the otherhand, it sounds like you did a decent job setting these up.

Bob, which image did you grab the blue channel histo from? I know he had a couple examples of intentionally over exposed to show what he is seeing.

Jamie,
As you said it was over exposed. Also, I'm not sure what you were focusing on?

To add to Bob's post, Adam Wilt's latest EX1 review he mentioned the following quote regarding EX1 highlights:

"I’ve found that the EX1’s knee does a fine job except when highlights are strongly colored. Saturated highlights show more hue shift and harsh clipping than I’d like. I’m exploring this further out of curiosity, but even if the knees were perfect I would still shoot with cine gammas, because I prefer the progressive compression to the look of a traditional knee."

After having read Bob's post, Piotr, I know you were using Bill's original TC setting which uses a standard gamma. Did you happen to try turning off the profiles and use the camera's default standard video settings?

That would of been interesting. Bill, I know you took great care in setting up the color channels. Maybe its possible that things are a bit hot with these setting which may drive the colors to clipping a bit early, which may be causing what Piotr has been concentrating on. But on the otherhand, it sounds like you did a decent job setting these up.

Bob, which image did you grab the blue channel histo from? I know he had a couple examples of intentionally over exposed to show what he is seeing.


The one from here http://www.dvinfo.net/conf/showpost.php?p=820805&postcount=53

I incorrectly named my screen grab Image41, it's actually from image42!

The green channel looks pretty much the same, the red channel isn't clipped.
This is always the problem with cameras that go to 11, if you have anything other than a specular highlight then having any channel go into clipping wierd things will happen if you're not very careful. Even WB setting can affect the color shift as you go into clipping. Trying to fix these problems in post varies from extremely difficult to impossible. Shooting it right is the answer. If that scene was being shot on film there'd be serious lighting in use and the DP running around with a light meter. Sony gave us a cheap camera that gets us one notch closer to film. We need to learn what DPs have been doing for nearly a century.

Probably what the EX1 should have is false color metering but that could be difficult to implement and again you need to know what it's telling you.

What do you mean by the camera goes to 11?

Some funky skies have also been seen in footage comparing the EX1 to the HVX. If I recall, default STD curve used. I can not find the link, so I frame grabbed a problem shot.
http://www.siliconcine.net/temp/Blew_Skies.jpg
White balance also looks too blue, a point Bill raised earlier for consideration. My gut feeling is the STD curve and perhaps the knee is the cause, coupled with exposure.

I posted this before in another thread:
From the XDCam HD brochure (the 350 series), we can see how different the Standard curve compares to the Cine curves, and a lot more of your highlights would have shown a burnt out look with "Standard" curve.
http://www.siliconcine.net/temp/XDCAM_Gamna_Curves.jpg

The Cine Gamma Curves for the EX1, from the brochure and manual.
http://www.siliconcine.net/temp/EX1_Gamma_Curves.jpg

Yes I saw this comparison too and also remember this being brought up.

There's no doubt that the image is way cool. It should of been white balanced. I believe the standard gamma was used. I also agree that the image is over exposed.
This may be just how the standard gamma blows out its highlights when over exposed. I have never seen this since I live on the cine curves.

We'll have to perform some experiments.

BTW, I have this same comparison, but it is 1080P version (Not the 720P version). The EX1 in the same shot does not show this problem. I'm not sure if they just did a better job with exposure, or they switched on a cine curve.

What do you mean by the camera goes to 11?

It can record right upto hard digital clipping at 110%. Some NLEs will clip that at 100% unless told otherwise.

Very interesting, Chris. When I looked at the b&w step wedges with the WFM, I compared STD with Cine gamma curves; and, initially chose STD for TC1 because it exhibited a more (vertically) symetrical wfm pattern, as I would expect with the STD curve you show in the F350 series curves. Overexposure indicated a definite cutoff at 100%. I, subsequently, changed to the CINE gamma curve for TC2 because of the more gentle rolloff characteristics at the right end. Furthermore, Adam Wilt writes the following about the CINE2 preset:
"• CINE2 – “broadcast safe cine”. CINE1 rescaled with whites limited to 100%."

If I get a chance, tomorrow, I'll post a screen capture of the WFM displays for the STD vs Cine Gamma curves.

Steven, I also observed the 1080p footage did not have the same funky sky as the 720p. Information from that comparison was perhaps not clearly documented and published.

I hope the following info is not too OT from Piotr's initial post and request for answers to this issue, however, it may have some general relevance and may assist those interested in comparing STD and CINE gamma curves:

It has been documented that even the F900's Standard gamma curve suffers in shots requiring a wide dynamic range. Have a look at this Standard curve image and the Digital Praxis custom gamma curve graphs applied to the camera/scene thereafter. Steve Shaw has been generous to provide a lot of information on the Digital Praxis site.
http://www.digitalpraxis.net/sonycurves.htm

You can see that the Digital Praxis custom gamma curves for the F900 blast the F900's Standard curve, compressing the range, lifting the blacks, preserving the highlights, and very nicely done by DoP, Geoff Boyle. Some curves are good for record, edit and finish with no grading (REC709 preset), others require post grading, however, there is more detail in the image and the right S shaped curves filter applied in post will extract the most out of the image (Bill Raven's "art"). The caveat I would add is that the EX1 codec, even in HQ mode, may have limitations to exploit such extreme PP settings that one may try to dial into the EX1 menus, such as trying to emulating the Cineon Log curve, due to the codec's 8-bit depth and compression likely not being robust enough to correct such extreme grading in post. In that case, recording via HD-SDI to an uncompressed 10-bit 4:2:2 device may be the next step for some. Thanks to Bob Grant for putting some of this into perspective for me, with his experience with the SI-2K camera and edit suite based on the CineForm codec.

Bill, your Wfm screen captures and explanation would be much appreciated, in this quest for knowledge and exploiting the EX1's goodness, to find it's limit!

After having read Bob's post, Piotr, I know you were using Bill's original TC setting which uses a standard gamma. Did you happen to try turning off the profiles and use the camera's default standard video settings?

Steven, thanks for joining the discussion. Let me address a couple of things:

1. Some of my grabs were intentionally overexposed to show conditions where ALL sky goes white. Yes I was checking with Vegas Histogram, Waveform and RGB Parade scopes and confirm that even the image41 shows levels upd to 110% (for Green and Blue). And yet it's the image41' exposure that one would use to "balance" between slightly overexposing the sky and showing details in the foreground - the camera' histogram looked normal to me, and nothing else spelled the disaster, either (all looked OK apart from the WB, but that has already been said).

2. To address Steven's question above: yes, I did try the same scenery with STD3 but Bill's PP off (i.e.default factory setting); the camera behaved in the very same way (auto-exposure, zebra and histogram - wise), BUT the image I got was fine in that I could properly expose the foreground (the sky went all white then), or keep the sky colour (with the foregroud a bit dark, but watchable).

3. As I mentioned many times before, it is the combination of Bill PP's modified Hisat matrix with the standard STD3 gamma that is a no-no. Why? Well, suppose one is already aware of what may happen to partially blow-out sky; he may either expose for the sky (to keep it safe and show the clouds etc), or for the darker foregorund (e.g. to show the face of a person standing there). Unfortunately, with this PP/STD3 combination, one must go way down with the exposure (much lower than the histogram/zebra would suggest) to avoid the patchy sky like I showed - so much so that the foregrund becomes already way too dark, and - due to the PP high colour saturation levels - oversaturated and noisy (see image38).

So, that the sky is clipping doesn't surprize me, as I wanted to avoid underexposed and noisy foreground. If the way it doesn't clip behind the trees is normal for a camera of this (high) class, as Bob is suggesting - is fine with me, as well. However - and I have said it before, as well - using high-saturation PP with STD3 curve is dangerous in that the zebra/histofram and autoexposure of the camera offer no help in getting the right balance (if it possible at all).

Thanks everyone for their participation.

I'm a little dark inside (the mantle) and totally blown out...especially in the window picture right.

I could have sworn the stuff I've shot with my XL-2 (my old cam) wouldn't have been so drastic...but this is a totally different camera.

Jamie,

I guess what you're showing with your picture is normal, though can see some traces of the strange abrupt blow-out beginning. I don't know your setting used with the picture you posted, it would be good if you remembered!

For comparison's sake, here go couple more examples of mine (sorry for the WB and focus being off; I took them while walking):

The first two are also through-the-window looks like yours; all factory settings used (i.e. STD3, but no PP at all). I don't think the outside is too much overblown.

The bottom two is the "horror continued" - the first pictures recorded while walking outside through the door (with Auto-Iris on), right after having dialed in Bill's TrueColour PP (SDT3 with Hisat matrix); note that even though I changed the WB quickly (to another bad value, but that proves to be of no importance), those trees against the sky look almost as if there was hoar frost on them!

Go figure...

EDIT: An idea occured to me and I went outside to check immediately - and yes, one can actually see the artefacts behind the trees in the camera's LCD! It's enough to switch peaking off (when I recorded these tests, I had it on with high intensity; since I was on autofocus the trees were all red with peaking, which obscured what was happening with the clipping around them...Now at least I know it's possible to observe and avoid this while shooting.

If I get a chance, tomorrow, I'll post a screen capture of the WFM displays for the STD vs Cine Gamma curves.

Please do, Bill! I've been searching for some graphical comparison of the STD curves with Cine gammas (the latter are depicted in the EX1 pdf brochure), but couldn't find anything.

Have some bad news for you guys - even without Bill's TrueColour PP, with the standard gamma curve (STD3, all factory setting) the ugly phenomenon when at the verge of sky clipping is still there :(

And, which is even stranger, it's bluish NOT because of the blue sky in the background; today I got it again with the sky totally overcast (light gray).

Evidently malfunctioning Knee/highlight processing, or at least totally not idiot-proof - even with the out-of-the-box settings!

Again, please try to reproduce it with your units, cause - after being somewhat reassured with the discussion in this thread - I'm again suspecting my camera IS malfunctioning, after all.

PS: Bill, I'm taking back my statements that your TC PP is a "no-no" with STD3 - if anything, it can only make the phenomenon even uglier by making the artefacts more saturated...

Well, if this is an issue with the standard gamma auto knee, Sony will address it.
Having said that, I use cine gamma curves and they are not showing this issue.

Well, if this is an issue with the standard gamma auto knee, Sony will address it.

I certainly hope so; nevertheless would appreciate somebody confirming it is not JUST my unit...

Anyway, here is the link to the short clip from which my last two grabs were taken (no PP, STD3 gamma, out-of-the-box settings); it shows how the artefact changes with iris opening/closing (original m2t, even with my Polsih comments in it; the format is SP 1080/50i as I was testing my DR60 drive - BTW, works fine with the EX1's i.LINK):

http://rapidshare.com/files/89637385/hilite_artefacts_SP_108050i.m2t

As most of you don't understand my Polish commentary: at the clip end the iris is at F8, and only then the effect vanishes (but the rest of image is severely underexposed). Also, I deliberately put the trees slightly off focus, as it seems to magnify the artefacting.

Again, please somebody confirm it's not just my unit! TIA.

Piotr,

Please post a similar scene where you:

-Use one of the Cine Gammas
-Center your Histogram
-White balance
-Focus

Then shoot it again in the Std 3 (as you have been) and push it as you see fit to prompt the potential defect that you are seeing from the camera.

I think that should be very helpful in letting others help you determine the likelihood of a camera problem.

Best,
Randy

Well, if this is an issue with the standard gamma auto knee, Sony will address it.


You want to put money on that guess? I'd like to beleive it but I wouldn't be sure. Not unless we make alot of noise.

Here's some links to the results of the 8 EX1 gamma preset readings I observed on an HDRack Waveform Monitor. In all cases, I used the factory presets with only the GAMMA preset changed. Everything else was at the factory setting.

Here are the caveats...PLEASE be sure you understand them before you make judgements about the results!!

1-Factory settings except for Gamma preset selection. Auto knee ON in STD mode, disabled in Cine mode.
2-Homemade 11-step gray chart--NO guarantees that the super black and super white are at 0 and 100 IRE
3-Scene illuminated by single 600w halogen lamp, minor skews in WFM due to uneven illumination.
4-White balance set to 2700K
5-Exposure normalized for each plot such that the white point always falls on 100 IRE (except for CINE2, see note 6)
6-CINE2 plot intentionally (over-exposed) clipped. Cine2 gamma clips, by Sony design, at 92IRE. This also accounts for the similarities in the middle gray point amongst the STD gammas.
7-I include a jpeg of the step chart for reference. Don't EVEN begin to think you can make some reasonable judgements from this jpeg. There are so many errors due to color profiles, that you'll send yourself down the proverbial garden path. Suffice it to say that the steps are evenly divided and symmetrical.

I see absolutely no evidence of premature clipping, weird effects, with the exception of Cine2, which is specialized, by design. I am putting some faith in whatever algorithm Sony uses to control the auto knee in the std modes. It's conceivable that this circuit can be fooled under some lighting conditions.

Non-normalized Cine Curves http://www.dvinfo.net/gallery/showimage.php?i=851&c=2
Non-normalized STD Curves http://www.dvinfo.net/gallery/showimage.php?i=853&c=2

Bill,
I'm confused about by your results because the cross over point is so high. Maybe its the "homemade grey chart"

Just looking at how your chart reproduces on my monitor it looks like there is nothing like a 90% white like you would see on a piece of white paper.
Is that true. Without it its a little hard for em to evaluate because I'm used to looking at a standard chart.
I've added 2 - 90% chips on the old standard chart I own anyway. It really helps understand where the crossover (gamma point) is and what your knees are doing relative to the rest of the scale.
Maybe its just the way I'm seeing your chart on my monitor though, or maybe you intentionally overexposed all the charts to show the knee and clipping?

I certainly hope so; nevertheless would appreciate somebody confirming it is not JUST my unit...

.

We cannot answer that until you post an example that is correctly exposed. How do we know by what amount your exposure is out to be able to exactly duplicate? YOU MUST DO THIS TEST AGAIN USING THE CAMERA PROPERLY AND THEN POST THE PICTURES IMO.

We cannot answer that until you post an example that is correctly exposed. How do we know by what amount your exposure is out to be able to exactly duplicate? YOU MUST DO THIS TEST AGAIN USING THE CAMERA PROPERLY AND THEN POST THE PICTURES IMO.

C'mon Michael - what do you mean "properly"? I've posted here the grabs of my camera malfunctioning, even though handled as usual (the WB and focus not being perfect didn't influence the issue I'm trying to show, the various exposure leveles HAVE been shown).

And yes of course when I use Cine1 gamma and there is no backlight clipping, my camera IS able to produce "proper" images, like one of those here:

http://www.dvinfo.net/conf/showpost.php?p=817542&postcount=103

Gotta agree with Piotr there was nothing wrong with his exposures. Yes the sky was overexposed but it often is on a daylight shot depending on your main subject matter.

If the sky was under 100% we wouldn't be having this conversation.

Piotr,

Please post a similar scene where you:

-Use one of the Cine Gammas
-Center your Histogram
-White balance
-Focus

Then shoot it again in the Std 3 (as you have been) and push it as you see fit to prompt the potential defect that you are seeing from the camera.

I think that should be very helpful in letting others help you determine the likelihood of a camera problem.

Best,
Randy

Randy, thanks for your input. To address your points:

- if I use a cine gamma, the prroblem is non-existent
- my histogram WAS centered. One thing that has been noticed by many is that - unlike with Vegas, where the whites are shown well over 100 IRE - in the EX1 LCD, it tends to be narrower
- white balance WAS wrong, but that didn't even change the colour of the artefact in question, not to mention its intensity
- focus. Yes, I need to recreate everything more systematically, this time observing not only those factors directly involved with the nature of the artefacting, but the focus, as well.

Cheers. Will keep you posted.

C'mon Michael - what do you mean "properly"? I've posted here the grabs of my camera malfunctioning, even though handled as usual (the WB and focus not being perfect didn't influence the issue I'm trying to show, the various exposure leveles HAVE been shown).

And yes of course when I use Cine1 gamma and there is no backlight clipping, my camera IS able to produce "proper" images, like one of those here:

http://www.dvinfo.net/conf/showpost.php?p=817542&postcount=103

The camera is NOT malfunctioning, the functionality of the user is rather questionable though.
Let's get real here. No one takes a camera like the EX1 and expects to not have problems without testing what they are shooting. Relying on a camera's histogram to guide you without testing and calibrating your metering and yourself is simply bad practice. I'm no great shakes as a cameraman but if there's one thing a few decades of enginering have taught me it's to test and calibrate anything before relying on it. Given that video uses variable non linear transforms, encodes into a system with severe quantization limits and uses metering systems that don't reveal the whole story, exhaustive testing of any planned shot is mandatory, even more so when adjusting things like gamma and saturation.

This would be the equivalent of a DP deciding to shoot on a stock that he's never used before without exhaustively testing it first. The ones that want to keep working still test stocks that they've used many times, they shoot the sames scenes, same lighting, use the same lab and the same print stock well before there's real talent in front of the camera. In other words the whole process, end to end. With cameras like the EX1, that whole process is pretty much under your control in the camera. Change any parameter and you need to test again if you haven't already tested what you're changing. If you get a funky result, maybe go talk to an engineer/technician or as most DPs would do, adjust their exposure and/or lighting or put the knob back where it was. In the digital realm it's for good reason that apart from the DP we now have a Digital Image Technician on the shoot. If you're wondering how relevant this is to using an EX1, change gamma or saturation or any of the other adjustments and it's the same as using a different stock.

I'll own up and admit that I've blown a whole days shoot and wasted the time of a lot of talent by trying to creatively use some of the tweaks in a lowly A1. Sure it looked fine on the histograms, it even looked OK on my CRT monitor. But what the camera had actually recorded was nothing like what the histogram showed or how the image looked on the CRT. The only thing posting screen shots would have proved was how daft I was, not what was wrong with the camera. I learned my lesson, apologised to the client and the talent and put my tail between my legs. Putting my engineering hat on I could understand what had happened and it was my fault it had happened. I'd changed a setup I knew would work without testing the outcome through the entire process. In a different lighting setup, with different things in front of the camera it would have been just fine.

In this situation the answer is very, very simple. You've found a lighting setup and camera setting combination that could produce a bad outcome. Just make a note of it, "need to protect highlights, underexpose 2 stops in high contrast scenes with sky". Now move on, I'll wager good money there's plenty more ways to get the EX1 to produce uglies.

To look at this another way. By your own admission, change the camera setup and your problem goes away. Well, isn't there a very basic lesson there, don't use those camera settings for that lighting condition or if you really must underexpose and accept the outcome. Even the pros shooting film do use different stocks for different conditions.

Thanks, Bob.
Patient: "But it only hurts when I laugh".

Well, Bob - I understand the only thing I'm supposed to do after your verdict is "put my tail between my legs", as you put it. I will, as most of what you're saying is true. However, let me just cite what has been said in this thread before, and not by myself, but an experienced videographer (bolds are mine, hope Leonard doesn't mind):

I have only looked at this shot in the stills on the web, but it looks like to me like something is wrong with a camera setting. It should not be neccessary for the operator to have to work around problems where the camera is treating the sky behind the trees differently than in the rest of the picture. I don't know what it is, but telling the operator to underexpose slightly may be a fix in this particular shot, but its important to figure out what is going wrong because a professional camera should not do that in my opinion.

Well, I have nothing to add at this point. Thank you all, and sorry fro bothering you.

Piotr:

Maybe we could see just how you exposed if you posted a frame grab of the vector-scope in your NLE. Then we can see what's illegal and what clipped. Please do this as this thread is getting you nowhere. Many experienced camera men here have contrary opinions mainly due to the lack of information you are giving us. We need more real information from you - we need see your scopes. IMO.

Piotr:

Maybe we could see just how you exposed if you posted a frame grab of the vector-scope in your NLE. Then we can see what's illegal and what clipped. Please do this as this thread is getting you nowhere. Many experienced camera men here have contrary opinions mainly due to the lack of information you are giving us. We need more real information from you - we need see your scopes. IMO.

Here you go Michael; the upper two is an EX1 grab along with its scopes; the bottom - similar scene with the V1E (standard gamma curve, as well). None of the images are perfect (fa from it), but the point is the "shadow" behind the trees only visible with the EX1 and not with the V1E.

I just tried a simple test with the EX1, hasn't been out of it's box today :)

Lamp with a diffused shade again a dark wall. Camera in manual, lamp filling around half the frame. EX1 histogram shows a nice lump in the middle, nothing anywhere near clipping.
Zoom in so the light is now full frame, the lump moves to the right of the histogram, looks like I'm getting pretty close to clipping. Zoom all the way into the slightly hotter middle of the lamp and on comes the Too Bright warning. Note I have not changed exposure while zooming in.

This is very different to how the scopes in Vegas work. The waveform display is the sum of all lines. If I'd recorded what I shot above and checked it with the Vegas scopes I'd see a lump in the middle of the waveform that was clipped. As I zoomed in the lump would get broader.

I just simulated the same kind of shot using Vegas generated media. Using Vegas's Histogram metering I get much the same thing. It's almost impossible to detect clipping with a histogram. In fact from what I'm seeing with histograms the more clipping there is in the shot the less noticeable it is in the histogram. With a whole frame clipped you just see a tiny line on the RH side of the display.

This article here:
http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml
gives a detailed explaination of what a histogram shows. About half way down the page there's an example of a scene very similar to the one causing all this grief.

I started a thread on this in the Vegas forum. An EX1 histogram that looks like it goes from 10 to 90 put into Vegas clips like it wants to go to 120. By this I mean extrapolate the shape of the histogram into the clip area that Vegas scope cut of. AND the Vegas scopes clip at the BOTTOM END TO! Like the blacks want to go to -20!

Also Piort I DID give my opinion as to what is causing this much earlier in this thread and no one commented on it so maybe everyone thinks I am wrong, but here is my take again. The EX1 gammas are not straight line or even a partial exponential of a log of a straight line, I think it is programmed to have the Gamma changes with luminosity. The area behind the trees has a lower luminosity (because the trees block the light) and the gamma drops in that area which brings the blown white back into the blue. I think this how the camera gets its enormous exposure latitude and why the Vegas scopes get stretched. JMO as they say.

The area behind the trees has a lower luminosity (because the trees block the light) and the gamma drops in that area which brings the blown white back into the blue. I think this how the camera gets its enormous exposure latitude and why the Vegas scopes get stretched. JMO as they say.

This explanation is the only one that can be thought of, Michael - and probably this is the reason nobody commented on it when you first suggested it. Assuming now that this is a byproduct of the "enormous EX1 latitude", one should simply be aware of it and, in backlit situations, either use cine gammas, or modify the Knee point/curvature of a standard gamma. I'd like this to be true, as the solution is so easy.

However, even on the scopes I posted here, the V1 also went well over 100 in Vegas, yet they sky is consistently blown to white, including the parts behind tree twiggies. This looks much more natural.

On top of that, please take another look at the picture Christopher linked to earlier in this thread:

http://www.siliconcine.net/temp/Blew_Skies.jpg

Judging from the overall look, I'd say a cine gamma curve was used - and yet do you see what's happening to the trees at the right upper horizon part?

So, I will be completely reassured only after considerable time of trouble-free shooting with the above recipe in mind, i.e. when I'm 100% sure that with cine gammas (or standard curves with modified knee), nothing like this can happen to my picture.

Piotr, factory default settings used on the EX1/HVX comparision, however, I can not be certain.
http://www.siliconcine.net/temp/Blew_Skies.jpg

Looking at the standard curve for XDCAM cam, IMO, why would you bother?
http://www.siliconcine.net/temp/XDCAM_Gamna_Curves.jpg

I understand your quest to solve this. Myself, I do not foreshadow dialing out of the four cine gamma options.

Piotr, factory default settings used on the EX1/HVX comparision, however, I can not be certain.
http://www.siliconcine.net/temp/Blew_Skies.jpg

Looking at the standard curve for XDCAM cam, IMO, why would you bother?
http://www.siliconcine.net/temp/XDCAM_Gamna_Curves.jpg

I understand your quest to solve this. Myself, I do not foreshadow dialing out of the four cine gamma options.

Christopher, if this was indeed shot with the same, standard curve, it'd mean it's not just my camera - and the solution being cine gammas, or standard ones but with modified knee. Thanks.

You're right in seeing this thread as a quest to solve/explain/understand an issue, and not another EX1 bashing. The fact is I only use standard curves for indoor, lowlight shooting when I usually crush blacks with their noise and try to catch as much mids and highs as possible. For outdoor shooting, the cine curves are so much better...

After filming a few shots I think Cine2 looks best.
I tried to get the same dynamic range with the STD3 Gamma, but I used too much knee as you can see.

The STD3-Picture looks much softer und muddy (maybe because I used too much Knee? 70)

http://img163.imageshack.us/img163/3095/vlcsnap64099cine2kf6.jpg
http://img352.imageshack.us/img352/4599/vlcsnap72289std3knee70ex9.jpg

regards Dennis

The trees are acting as nets or scrims in the "problem" images. They are dropping the exposure of the sky... and hence your results.

As you zoom in, or even better walk closer, to the branches this should "magically" go away. This is because eventually the branches are too far apart to operate effectively as a scrim/net.

You will observe the same effect on diffuse lights, and especially lights with nets or scrims on them.

You will observe this with any camera. The exact circumstances will vary a bit based mostly on the sensor resolution, lens resolution and to some degree on the exposure. The main point is that regardless of what camera you are using you will find some combination of fine elements that will trigger this perception- that includes your eyes.

That is just the way light works.

All the talk of gamma levels and matrices is off the mark. No really - all of it. Go shoot that same scene with an HVX200, RED, a Viper or 35mm and you'll get similar results. (Again accounting for the sensor and lens resolution.) That isn't to say anyone's been wrong- just wrong that it has anything to do with the "problem."

The one note is that the issue is made more prominent by the XDCAM codec. Capture that as ProRes and while you'll still see the problem, but it will be less objectionable.

The case presented here (http://www.dvinfo.net/conf/showpost.php?p=820095&postcount=1) can be "solved" in one of two ways:

1) drop exposure so that the entire sky has a valid exposure level. The differences in exposure in the sky will thus be less objectionable.

2) increase exposure levels so the sky well and truly blows out, then do a sky replacement in post.

3) use a filter or grip kit to bring levels down in the sky. I'd try a graduated ND filter first.

A circular polarizer might help a great deal. It would bring exposures down a bit and may have some effect on the fringing.

If it was a film set with a still camera I'd drop a net very close to the lens (and out of focus) to bring the level down in the sky. The net will also give that portion of the image a little softening. The problem with nets is that the edges are sometimes too thick.

For a lot of ENG/EFP video work I'd just live with it during acquisition and maybe throw a vignette and a soft blur on the image to drop the levels and sharpness there a bit. That would soften the effect a bit. There is no post solution that will really fix that sort of thing though once you shoot it.

OK guys - you got me convinced that this is not actually a flaw, but a feature. I did some backlit shooting today with all the factory setting, but the Knee point of the STD3 curve dialed down from 90 to 75.

The result is that I can no expose the darker foreground much better before they sky even starts to overblow (which was expected). However, once it does, the trees act exactly the same i.e. before the exposure is too high (and whole sky is simply white), it goes though the same stage where the sky areas right behind the trees become blue-gray (ugly and unnatural, as the rest of the sky is already white).

Now, my question is this: apart from changing the knee point, should I also change the slope and/or sauration in order to minimize this effect? Please give me some theory background to this; let me stress that I'm no longer looking for "flaws", but investigating "features" :)

The steeper the top slope of the curve the less risk of banding in gradient highlights e.g. sky. If you look at the curve you'll see that a quite large change in light (the X axis) produces a very small change in the output (the Y axis).Unfortunately the sky can as you've seen fall right along that slope. Part of it ends up clipped to white, the next darkest region has some color in it but two channels are clipped still so the color shifts.
Drop the exposure and the sky slides down the shallow slope and out of clipping. Increase the exposure and it all clips to white. Except you are maybe overloading the sensor. Look at the curve and see just how much light you're pushing into the camera to hit clipping. With that amount of light the sensor itself starts to do and see wierd things, like lens artifacts, light bouncing around between lens elements and inside the prism.
My suggestion would be not to use that curve in that shooting scenario. If you want to shoot that scene with natural looking blue sky and still preserve detail in the shadows you either need to add light to the shadows or reduce the brightness of the sky. I think someone previously had mentioned how to knock the sky down with a net, this is standard fare, either that or else adding fill lighting to bring the dark parts of the scene up.
Or even simpler, shoot with the sun in a different position or at a different time of day.

One thing that doesn't help is Sony haven't published any real gamma curves. The ones they have have no scales, they give a hint as to what's happening but clearly for example the std curve cannot go to 200% or if it does then the cine curves only go to 50%. Maybe what they mean is the top of the std curve is 100% for that curve and the top end of the cine curves ins 100% for that curve. Putting them all on the one chart like that might be graphically appealing but very confusing.

If you look at the black wedge WFM pictures I posted, you'll see that the top end of the gamma curves in CINE mode are a fraction of the top end point for the STD curves, reinforcing the XDCAM HD curves you showed, Christopher.
This surprised me when I first saw them, which is why I, initially, normalized them to 100 IRE.