abrupt highlights clipping

[Piotr Wozniacki]

No comments? ;)

Well, here is a go:

upper: TC2 with CINE1
lower: TC2 with STD1, and both Knee point & Slope UP (and I mean waaay up, too!)

I also tried STD1 with Knee and Slope down from default, but the compression starts much too early, effectively neutralizing the extra headroom for highlights that the STD1 offers. So - as could be expected - rising the Knee allows for an even brighter picture. It's easier now to blow highlights past the "abrupt clipping" zone; however I am still unsure whether the Slope should be up as well, or lowered, or unchanged - in order to narrow the offending (abrupt partial clipping) zone...

Any theory behind that?

PS Sorry - I was so busy tweaking in haste that I didn't notice at once how crappy my tripod was positioned :)

[Alexander Ibrahim]

Originally Posted by Piotr Wozniacki

With the EX1, a third factor is involved: how to avoid the clipped colour patches I can't even see in the LCD while shooting? I certainly consider the way it handles it as being flawed; it's not just the question of inevitable clipping!

Welcome to the world of extended dynamic range.

For the first time your foreground subjects and background fit within the camera's ability to render images. Just barely as it turns out, but they are there.

These colored areas are REAL. They are there if you turn your eye to that portion of your scene.

The V1 would need to be set to a useless exposure to create this effect. The foreground would be far too dark and the sky still hopelessly over exposed

I haven't been able to do a latitude test on the EX1, but I've read that the camera gives 10 stops. Seems about right.

If the camera had a latitude of 11 or 12 stops you'd see the "problem" blossom into complete detailed skies on a lot of these shots.

For instance, can you tell me why are those patches always bluish - regardles whether it's clipping the blue sky, or a gray cloud?

Because its SUNLIGHT that's causing the effect in both cases. Your looking at either hard sunlight in clear skies or diffuse sunlight in cloudy skies.

If you create an analogous situation using a tungsten light source then the effect will appear to be that characteristic yellow orange tungsten color.

So frankly I really DO consider these to be flaws in practical use outside a controlled environment like a studio.

I see you never did understand me.

Everywhere the photographer works is a controlled photographic environment because the photographer is imposing control on the environment.

That gentlemen is the the nutshell description of our job.

A photojournalist (i.e. a news photographer) has a different task- they are to capture the scene as it was without altering or modifying it. In that regard any number of picture problems is acceptable provided that the image represents the reality of the event. This means that the photojournalist must exert only unobtrusive photographic control.

Even so in news videography cameramen place lights, use reflectors/bounce, hang nets or silks and do all sorts of modification whenever they can.

I certainly didn't put those lights and grip gear in the truck, I didn't even know what it was back then! I'm guessing ABC put it there... and I'm further guessing that they meant for me to use it when they stuck it in there.

So... why aren't you controlling your scene?

Without tweaking, the picture from my EX1 is much worse than that from the V1E I had

<sigh>That statement is enlightening, and I disagree with you vehemently.

This camera can do a TON more than the consumer cams you say you've used... but it also won't do any of it for you.

Think about this for a minute- either I am right and something basic about photography is hurting how you take images or Sony is selling a worthless piece of junk for way more than its worth.

Let me put it differently... if you are runnin and gunnin all fast and furious and some new situation rears its ugly head, you won't have time to sit down work through the menus and create a picture profile for the occasion.

If you did have the time, it would be far quicker to throw a little net on a french arm off your tripod's neck and go. If you have the right stuff it would be even faster to throw some graduated ND in the filter box and adjust it.

If you are geared for film, you could light the subject to raise their exposure to something you like... a 1K HMI will work wonders... but now you ain't running- which is why I didn't suggest it before.

There is only one possible explanation, or if you like: excuse, for the above "peculiarities": if the EX1 is treated as a stationary camera for shooting under carefully controlled light, and with enough time to set-up each take - the flaws (including sticking ND switch) become irrelevant. With ENG use, however, they are really serious

A stationary camera? That's the worst mischaracterization I've ever heard. Come on!

All this because I suggested using a graduated ND filter in a rotating matte box? Or a net ? Oh dear.

I will say this... everything I suggested is something you can do at or near the camera, and yes even with a run'n'gun field rig while hanging loose out the back of a truck in the jungle on assignment for Nat Geo. For the record that would be a moving camera.

My advice is only predicated on the notion that you want to take time and care with your image.

Frankly right now your worst "abrupt clipping" results are perfectly fine for ENG use. The compression for sat trans will do far worse to your image. I seriously doubt you are really complaining that much about this camera for ENG use though. Putting on my "ENG shooter hat" I can think of a hundred things to complain about the EX1 before I mention the image.

I am guessing that you are doing EFP and low budget indie film. That's fine... that's how I've been using it, and I expect to do plenty of guerilla film making when I own my own. The main point is that if you are doing indie film or working industrial videos say so... don't pretend your working news.

If your real complaint is that you can't get feature film results out of the camera while using ENG or combat camera techniques then ... well I can't help you.

(is there anything you could call "a take" in run'n'gun shooting?).

A take is anytime the camera is recording.

Since you are a run'n'gun video guy you may consider the phrase "during a take" to be exactly equivalent to "while recording."

With its handycam form factor, has the EX1 been designed as a stationary-only (or -mainly) camera? From what you are advising, Alexander, I take it that you're advocating to use it that way...

I suppose I advise using any camera "that way" whenever you can.

I'll repeat that your calling my suggestions suitable for "stationary-only" cameras is a mischaracterization at best.

That said I think the EX1's ergonomics make it less than desirable as the run'n'gun ENG camera you seem to be searching for.

If my job was to shoot with the camera handheld and on the move all day I'd look for a shoulder mounted unit, and I'd probably turn my eye towards the HPX500 or maybe the XDCAM HD F330. I love solid state though, so I'd probably go to the HPX.

PS. Oh, and Alexander - even if you never switch auto iris on during shots, could you just check it for me, please?

Yes I'll check it next time I have an EX1. FWIW I get that on the camera I have with me. As Bob suggested it seems to be a servo driven thing not an EX1 thing.

[Alexander Ibrahim]

Originally Posted by Piotr Wozniacki

No comments? ;)

Piotr, could you please post your metered readings for the foreground subjects and the sky as well as all the camera settings for your images.

When posting comparisons please don't change ANYTHING but what it is you want us to examine between shots.

For example in these shots it looks like a cloud has moved from behind your camera placing more hard light on the foreground scene. Also you panned left and tilted down and... the list goes on.

It would be better if the two shots were absolutely identical, with the ONLY difference being the change in picture profile. Same iris, zoom, focus distance, lighting... same everything please.

A spot meter would be ideal for this issue- if you don't have one please buy, beg, borrow or steal one.

[Steven Thomas]

I'm not sure where all the fuss is coming from... I've been taking jaw-dropping footage with the EX1.

If you're not happy with the EX1, sell it quick. Since it's only been out for three months, I'm willing to bet you will get top dollar for it.

[Benjamin Eckstein]

Originally Posted by Steven Thomas

I'm not sure where all the fuss is coming from... I've been taking jaw-dropping footage with the EX1.

If you're not happy with the EX1, sell it quick. Since it's only been out for three months, I'm willing to bet you will get top dollar for it.

Amen! Definitely. Either return it if its defective or sell it if its not what you want. If I was as unhappy with it as you seem to be I'd try to recoup my costs as quickly as possible. I think this thread has gone on long enough with no conclusion to indicate that nobody has a real "solution" to the "problem".

[Piotr Wozniacki]

Alexander,

Thanks for your elaborated and enlightening post - I really appreciate the effort you put into answering me. However, as others seem to be getting impatient, I am giving up further delving into this subject.

I would like to say though, that if I was understood to be totally critical about the EX1, than I was misunderstood. Perhaps this is a matter of my English. For instance:

- I didn't say it's a "stationary" camera; I said that your advice about nets and alike would be better suited for a stationary camera / environment

- I didn't say it gives worse picture than the V1E; I said it does when straight of the box, and compared to a properly tweaked V1 - etc, etc.

Anyway, I guess that those impatient with me would do a better job by providing their own examples of the "abrupt clipping" and how they control it, instead of their catty remarks. It'd help users like me come to terms with it, as we'd have to accept it as 100% normal for all EX1 units. The thread has lasted for 3 week, yet the only examples were mine - all the other kept saying it's perfectly normal, but no picture was posted! And, when I ask for general suggestions about the Knee settings to alleviate the phenomenon, nobody answers... Oh, and regarding the above comparison: of course the clouds moved; I couldn't stop it - don't have two EX'1 to shot simulatenously, either.

Thanks again, Alexander:)

[Steven Thomas]

Users are posting samples of their footage all the time...
I'm not sure what you're talking about.

My guess is there are quite a few users now on this forum.
I don't really hear anyone complaining but yourself. Why would we
post something that's not bothering us?

I'm happy with the exposure coming from the EX1. In fact, it has a LOT more control of getting the right exposure and the headroom than my other cameras could offer.

[Piotr Wozniacki]

Steven,

Just to make myself clear, as you obviously didn't get me: people ARE indeed posting their best pieces (I have shot some nice stuff, too), and I enjoy and admire their work. But this is not the point; I'd like to see somebody post the exactly same effect of "abrupt clipping" as I did, along with some technical hints to avoid it (other than controlling how the scene is lit, and preferrably in the form of the camera tweaking with gamma, its Knee settings etc.).

[Steven Thomas]

You're right, I'm not following.

What are you trying to acheieve from this further discussion?

If you don't like the "abrupt clipping" I say stay away rom clipping. If you find that you can not achieve what you believe should not show your issue, I'd suggest either living with it, or sell it.

I'm having ABSOLUTELY no issues with mine. In fact, I'm seeing more latitude than my previous 1/3" cameras. You need to pay attention to not just luma, but your color channels.

[Piotr Wozniacki]

Originally Posted by Steven Thomas

If you don't like the "abrupt clipping" I say stay away rom clipping.

Very true. I guess this thread could be summarized as follows:

Abrubt clipping results from the combination of the greater dynamic range and some peculiarities of highlight compression handling around the knee point.

Once we're aware of it, we can avoid it - but with the current firmware, only in manual iris. For run'gun'style this is not always practical. With Cine gammas, engaging auto iris - while helping to stay on the safe side and avoid the abrupt clipping - tends to waste a lot of bandwidth in the highlights; with STD ones - auto iris sets the exposure right into the abrupt clipping area.

I guess we would be just fine if Sony included in the future firmware what I mention here:

http://www.dvinfo.net/conf/showpost....5&postcount=61

[Leonard Levy]

Piotr,
I tried to emulate the shot you took with the trees at the beginning of this thread and wasn't able to do it but I will try again when the sky is different if it still seems to be a problem.

I was quite concerned about it and do agree that the effect you showed was unacceptable, not normal in a professional video camera.

I confess I got lost in this thread and stopped following it as most of the responses that got into discussing histograms ( a complete waste of time IMHO) post processing, and correcting with lighting or exposure have seemed pretty irrelevant . Also I'm confused by the frame grabs you posted just above of the house and trees. Both of those looked fine to me though maybe I didn't look hard enough. Are those supposed to display the effect you're describing ?

At any rate, you might try just setting a manual knee at around 93 - 95 and see if that helps. I'll check where I put my slope as that might be relevant but i think the default was probably OK.

The auto knee on this camera is overly aggressive and when activated above 100% will suddenly start compressing things that are below 100%. This is not good. Most good video techs will tell you they hate auto knees in general and I know I have seen auto knees out of the shop from Sony on expensive professional cameras that are set way way off.

Adam Wilt told me the other day that he has detected a flaw in the knee (not just the auto knee) on the EX. If I heard him correctly, he said that when an image has high saturation the knee acts strangely and begins working on the highlights then as they get brighter it abruptly stops working and the level jumps up. I don't know if this might be connected to what you observed, but who knows.

For my own part can you simply repeat when this occurs - i.e what gammas, knees, what zebra points, etc. and also confirm for me that you haven't done any post processing at all to the original images. I'm sorry if this is already stated in this thread but it is very long and I seem to remember that maybe you retested a few times.

Lenny Levy

[Piotr Wozniacki]

Thanks Lenny for re-joining in.

You're right that the discussion has drifted away from the main subject; and no - my last two grabs are NOT showing the abrupt clipping (they've been posted to show how - with Auto Iris ON - the bandwidth may be wasted in the highlights when Cine gamma is used, and how much more punchy the STD1 gamma is).

It's a pity you stopped participating in the discussion, as - at some point - I felt a bit isolated in my opinion about the abrupt clipping (as shown at this thread beginning) being unacceptable. Some users kept telling me it's absolutely normal, yet nobody posted his own example of it! Now you're telling me you can't reproduce it - strange...

Your idea of asking Adam Wilt to express his opinion crossed my mind earlier, but I have no idea how to contact him - can you share a contact you have (you can e-mail me if you prefer). Cheers

Piotr

PS. Lenny, with my camera it's absolutely simple and easy to reproduce the problem; in fact it's enough to leave the camera with auto iris on - sooner or later, with some trees against the sky, it will appear (more often with STD gamma, and Knee auto; I can "stretch" highlights past it into complete blown-up area by deliberately overexposing, or underexpose a little to be at the safe side. With Cine gammas, I'm on the safe side most of the time - but it can happen as well).

[Leonard Levy]

Originally Posted by Piotr Wozniacki

it's absolutely simple and easy to reproduce the problem; in fact it's enough to leave the camera with auto iris on - sooner or later, with some trees against the sky, it will appear

If you can be a bit more specific it would help me try to reproduce it.
Is this against blue sky only? against blue mixed with clouds , completely cloudy as well, etc.?

Does the zoom length matter? Where on the IRE or zebra settings does this occur?
Does the gamma or knee setting matter once you are up into the zebra areas?
I don't care what happens on auto exposurethat just muddies up understanding it for me. Just want to know if the knee or cine gammas make a difference when you are in the slightly overexposed areas where this occurs.

Lenny

[Piotr Wozniacki]

Originally Posted by Leonard Levy

If you can be a bit more specific it would help me try to reproduce it.
Is this against blue sky only? against blue mixed with clouds , completely cloudy as well, etc.?

Doesn't matter whether the sky is half-clear or cloudy - it is always bluish cast around the tree branches. In fact, it DOES NOT happen when the sky is deep blue, as this is safely below 100 IRE.

Originally Posted by Leonard Levy

Does the zoom length matter?

Usually happens at full wide, but I can't see direct relation to zoom position - apart from the fact that when I'm zoomed in, I'm more likely to notice it in the LCD and adjust exposure to avoid it

Originally Posted by Leonard Levy

Where on the IRE or zebra settings does this occur?

Just below 100%

Originally Posted by Leonard Levy

Does the gamma or knee setting matter once you are up into the zebra areas?

No. Whatever gamma, knee, slope, matrix etc. it CAN happen; but obviously as I said earlier it's easier to be avoided with "safe" gammas like the Cine2, or with Knee set lower than default on STD gammas, etc.

Leonard, I have e-mailed Adam Wilt with a kind request for his opinion; I attached an example grab and the link to this thread. However, if you are in touch with Adam, please ask him to take a look at it.

[Piotr Wozniacki]

OK - so I've just got a response from Adam Wilt. While I don't feel authorized to quote it here (seems like Adam is still looking into the problem, and will have more to say about it soon), I'd just like some of you guys to know that I'm not being paranoid about it; Adam confirms that the "abrupt clipping" - while present on all EX1's he's seen - just doesn't happen on other cameras.

Which is exacly what I've been saying. Now, let's wait for what Adam is going to tell us about it; in the meantime I've learned how to avoid it when possible, or live with it when necessary. Let's hope the future firmware will address it.

Leonard, I'd like to thank you for backing me up and encouraging to contact Adam, rather than accept what others were saying about this flaw being "a normal thing"...