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?

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....&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.

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.

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):

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.

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/tu...stograms.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.

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.

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/img163/3...99cine2kf6.jpg
http://img352.imageshack.us/img352/4...3knee70ex9.jpg

regards Dennis

You have all over thought this one
 

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 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.

Bob and Bill, the F900 Standard REC709 setting is up at around 150 IRE, likely the same in the XDCAM graph.
http://www.siliconcine.net/temp/XDCAM_Gamna_Curves.jpg

Alfonso Parra, DoP, has performed F900 tests on the Digital Praxis custom curves. If you look at this image/graph, at 400%, the F900 Standard curve runs up to 150 IRE. The other curves are the Digital Praxis customs, somewhat similar to the EX1's cine gamma, except closer to Cineon log and some ideal for intense post grading and film out. This provides some perspective of what the STD curve values may be, and IMO, can be applied to the EX1 STD curve, as approximations of the X and Y values. The EX1 is after all part of the CineAlta family.
http://www2.alfonsoparra.com/php/ima...nt/167/049.jpg

This might be a stupid question, but, isn't the implication that the cam is more light sensitive in STD mode?
Furthermore, highlights will appear to clip in any NLE that can't handle IRE values over 100-110%?
Or conversely, crush the blacks if the highlights are exposed properly?

Bill, I looked at your WFM wedges, thanks. When looking at Alfonso's wedges, they appear exposed 18% grey wedge to 50 IRE on the WFM, and then observe how the different curves responded to shadow and highlight detail.
http://www2.alfonsoparra.com/php/ver...&id=134&ln=eng

The image recorded is not always appealing, however, in post there should be the most amount of detail preserved to extract, however, an F900 and the EX1 have different codecs and data rates, and one will be limited by how robust the EX1, in HQ mode, holds up, and how far your can exploit it in post, if one makes extreme presets, similar to Cineon log curve.

My EX1 arrives next week, so lots of testing to follow, in due course.

Exactly!! ;o)

This is becoming funny... I know you guys don't regard me high as a camea operator, but I have just finished my next couple of tests, and have a couple more surprizes for you:

1. Even with cine curves, at the moment EX1 starts clipping (and you cannot totally avoid it), the resulting colour patches are awful to watch (see the left grab: as if the blue colour resosution was insufficient). In the right grab, I was those tiny fractions of a stop on the safe side, and the sky exposed better.

2. I'm not sure, but I guess I have found the vignetting problem source; do you recognize the upper right corner thingy in the right grab? - well, it is the ND filter not quite snapped in...What a silly construction, and why no knob to rotate it quick and precisely?

Anyway, even though I really appreciate your experience and knowledge, I can now state it with 100% certainty: the highs compression algorhitm on the EX1 is faulty. You're simply wrong saying that all cameras do that; my V1E doesn't do that - period.

Piotr, I don't judge you on camera ability. I too have my EX1 learning to come.

I loaded those frames in PS and reduced the saturation value to -50, then the trees and sky don't stand out so much. Perhaps the funk is a combination of these particular settings, coupled with exposure? Hisat on, perhaps try another?

Piotr, I believe what their saying is that the EX1 has more latitude; therefore, how it rolls into over exposure and how it's perceived is going to be different, than say your V1E.

I'm not knocking your opinion, it's just that you seem to be the only one concerned with this.

I've taken great day light shots with plenty of sky holding decent latitude allowing good exposure for the bottom half of the image.

Sure, the problem is that you have no real benefit of this latitude: here is the grab perhaps some half-a-stop less exposed that image54 in my previous post; this is how the sky really looked (well, almost: there still is a single, unnatural patch of light blue there). Why no gradation between the blue tones, but the abrupt change in colour? This simply shouldn't happen - nobody will tell me one of these two grabs is poorly exposed (if anything, perhaps slightly off-focus, as it was a walking shot). And when you watch those changes in the actual video, it looks even worse because the patches appear and disappear constantly all over the sky.

Saturation, over.....

Yes, it's all with Hisat matrix. But the Standard one looks muddy - and again: on the V1E, when I choose Cine1 gamma and Cinecolour on, I have everything at least as saturated as with the Hisat on the EX1, but still no patches when slightly overexposed.

I'm going to give the Cine matrix with one of Cine gammas the last try tomorrow.

Piotr,
Are you believing that the closely paced branches in the sky view do not reduce some of the sensor illumination at those given points?

I believe Alexander and a couple others have mentioned this. I'm not sure why you think it should not. Also, since I'm away from the office, I did not bring the image in and analyze it, but the sky sure looks over exposed in some locations. I know you doing the over exposure on purpose, but I'm not sure where this is going....

Piotr, if you think there's a problem with your camera you may want to return it for exchange. If you feel it's across all EX1 cameras, I suggest asking for a refund if they will still honor it.

Exactly Thomas - I am over and under exposing on purpose, to learn the new camera limitations and discover its strengths. Where is it going? Well, I thought I said many times: I'm trying to find a way to avoid abrupt colour changes (nasty patches) where the camera is just on the verge of, or slightly crossing, the clipping boundary. So far I haven't succeeded; I agree that tree foliages are enough to limit the amount of light just like some sort of ND filtering, but the resulting patches are washed out of any colour gradation, as if the colour resolution was insufficient (I'd call it near-clipping banding). The V1 doesn't exhibit this, so please don't tell me it's normal.

Too late - I've just sold my V1E:)

Seriously though, I still hope I'll find a solution. BTW I am trying to be as neutral in this topic as possible, even though have been attacked a couple of times myself as a "unfuctional" operator, so let's just forget it for a while.

Nobody even commented on the vignetting caused by the ND filter - could it be something quite separate from the infamous vignetting problem?

Piort:

To get you out of this rut, let the past go and start afresh like this, then see if you have same problem:

1. DO NOT USE STD curves. They are not made for the likes of us. There are just there for comparison or to add some bells et. Also with the CINE curves knee is automatic so that goes out of the equation.

2. Try CINE4 it gives most detail in the blacks.

3. Choose HiSAT but leave all other settings flat.

4. DONT EXPOSE BY THE HISTOGRAM UNLESS YOU HAVE CALBRATED IT. On my camera it grossly over exposes even when the LCD look reasonable. YOU MUST USE ZEBRAS.

4. DO NOT USE ZEBRA 2, it is set at 100% which is way too high for this camera when in good light. Set your Zebra1 to 95 and expose so you see no zebras, yes NO ZEBRAS, in the sky.

Then tell us what you see in your NLE.

Bad advice, Stevens. I disagree with practically everything you've said.
I believe the STD curves may not look too nice on the VF, but, they capture the most detail; and, it's up to the editor to bring that out in post.
On the contrary, I've found that exposing to 100% zebra still shows detail in the white. I've never seen another camera work like this....100% zebra blows the hilights completely out on other cameras, but not the ex1. In fact, I've begun to shoot with my TLCS levels set to +0.5.
The histogram is calibrated for the capabilities of the camera CMOS, not necessarily the 0-100IRE range of an NLE. CINE3 shows the most detail in the blacks, but, at the expense of the middle grays and hi's. CINE4 is the best compromise for a high dynamic range scene. Cine 3 works for scenes without as much hi-lite, But CINE1 works very well for low dyanmic range.
The factory matrix, even in hisat, is off in the greens, cyan and blues. TC2 color matrix resets for more realistic colors in all modes.

Ravens:
As for you liking STD to give your more detail in post you forget that the sort of processing the CINE gammas do is much better than doing the same adjustments in post. The closer you can get to the look you want in the camera is always best.

As for 100% Zebras, all I can say is on my camera, using the CINE gammas, 100% Zebra blows a lot out. Now I know the camera claims to record to 108% and I do see that in my NLE, but my camera gets no detail in this range and is fully white blown, at anything over 95.

Michael,
i have to agree with Bill. In the real world of video production it is impossible to choose to shoot with nothing over 100% especially exteriors.
Thjat's just a fact of life in my world.

It may be that the cine gammas on this camera are the only viable option, but they shouldn't be and if theym are its a significant flaw that should be corrected. Cine gammas do a lot of compression which may or may not work for your shooting style and the subject but the camera should not be artifacting under normal gammas.
I'm going to look into this this afternoon and if I learn anything I'll post.
Lenny levy

I'm going to have to ask the obvious question. If 110% is the point of digital clipping how does the camera record 150%?
I think I can understand how this in fact works but if so aren't we way outside Rec709?
If that's the case then NLE's such as Vegas are going to get the conversion to RGB wrong. Even more worrying is how that holds up in an 8 bit pipeline and recording system.
Might be interesting to hookup a 10bit scope to the HD SDI port.
Would I be way off the mark in suggesting that some of these gamma curves could be optimised purely for the 10bit HD SDI output and not used when recording with the 8bit XDCAM codec at all. I know trying to get something from Cineon into 8 bit can be difficult with banding problems pretty easy to come across.

When I first got my hands on the camera I commented that the ND filter control was not good. That you've managed to only partially engage a filter comes as no surprise to me at all. The ND filter control and the power switch need a lot of care and attention in use. Yes I agree, not well done at all.