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-   -   abrupt highlights clipping (https://www.dvinfo.net/forum/sony-xdcam-ex-pro-handhelds/113933-abrupt-highlights-clipping.html)

Piotr Wozniacki February 28th, 2008 09:00 AM

4 Attachment(s)
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 February 28th, 2008 11:38 PM

Quote:

Originally Posted by Piotr Wozniacki (Post 833834)
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.

Quote:

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.

Quote:

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?

Quote:

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.

Quote:

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.

Quote:

(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."

Quote:

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.

Quote:

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 February 28th, 2008 11:54 PM

Quote:

Originally Posted by Piotr Wozniacki (Post 834586)
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 February 29th, 2008 12:13 AM

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 February 29th, 2008 12:33 AM

Quote:

Originally Posted by Steven Thomas (Post 835047)
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 February 29th, 2008 03:39 AM

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 February 29th, 2008 08:45 AM

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 March 2nd, 2008 04:35 AM

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 March 2nd, 2008 10:01 AM

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 March 4th, 2008 09:14 AM

Quote:

Originally Posted by Steven Thomas (Post 836165)
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 March 4th, 2008 10:45 AM

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 March 4th, 2008 11:07 AM

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 March 4th, 2008 12:22 PM

Quote:

Originally Posted by Piotr Wozniacki (Post 837228)
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 March 4th, 2008 01:07 PM

Quote:

Originally Posted by Leonard Levy (Post 837272)
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.

Quote:

Originally Posted by Leonard Levy (Post 837272)
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


Quote:

Originally Posted by Leonard Levy (Post 837272)
Where on the IRE or zebra settings does this occur?

Just below 100%


Quote:

Originally Posted by Leonard Levy (Post 837272)
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 March 4th, 2008 03:27 PM

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"...

Steven Thomas March 4th, 2008 05:06 PM

Piotr, you brought this thread full circle. It was already brought up earlier in this thread that Adam saw that saturated highlights show more hue shift and harsh clipping than he'd like. Adam also mentioned he would explore it more later.
Piotr, I don't believe no one disagrees that it can look bad when it clips.
I believe most do not care since they are not having an issue. If it clips, we back off.


Here again is what Adam Wilt wrote in his review:

"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"

Tom Roper March 4th, 2008 09:53 PM

Piotr,

You mention that the phenomenon is observable when auto-iris is on. Can it occur if you used auto-shutter, or just auto iris? In other words, is the effect related to highlight clipping at the upper end of exposure, or possibly diffraction, which could happen with a small aperture but would not happen from a fast shutter?

I hope my question is not confusing. One thing I'd like to understand, is if the problem could be avoided by using a fixed aperture with shutter priority, instead of the other way around.

Piotr Wozniacki March 5th, 2008 02:51 AM

2 Attachment(s)
Quote:

Originally Posted by Tom Roper (Post 837518)
Piotr,

You mention that the phenomenon is observable when auto-iris is on. Can it occur if you used auto-shutter, or just auto iris? In other words, is the effect related to highlight clipping at the upper end of exposure, or possibly diffraction, which could happen with a small aperture but would not happen from a fast shutter?

I hope my question is not confusing. One thing I'd like to understand, is if the problem could be avoided by using a fixed aperture with shutter priority, instead of the other way around.

No Tom - it's no connected with aperture values (and possible diffraction). It can occur with any aperture, as long as you don't move away from the exposure range that it's occuring in - by either slightly opening aperture (to blow out completely), or closing it (to stop clipping completely). And of course, you can achieve the same with shutter speed, if keeping constant aperture is yur priority (though you cannot be as precise as with the iris ring).

PS. Since this thread has drifted off its main subject, here is a grab to remind what we're talking about. And what Adam wrote to me when he saw this picture (I've just got his permission to publish, so that more users can benefit):

Hi Piotr,

What you are seeing is normal for STD gammas on the EX1, and it is
exactly the thing I found peculiar. You are right in observing that
it doesn't happen on other cameras, but it is there on all EX1s I've
seen.

I hope to have more to say about it soon, but for now, my advice is
not to trust the STD knees to protect or roll off your highlights
smoothly. Instead, use CINE gammas where important parts of the scene
are bright, like the sky in your image, and switch to STD gammas only
when you have control of the lighting, as in indoor interviews, or
when you do not care if the highlights blow out sharply.

CINE4 is very close in linear scene response (before the knee or the
curve) to STD3, so you might set up two Picture Presets, one on STD3
and one on CINE4 but with all other parameters the same. Switch
between them, using CINE4 for contrasty exteriors and long shots, and
STD3 for close-ups of bright faces where CINE4's desaturation is less
pleasing.

Cheers,
Adam Wilt

Tom Roper March 5th, 2008 08:36 AM

Quote:

Originally Posted by Piotr Wozniacki (Post 837594)
... here is a grab to remind what we're talking about.

I remember. I've read closely since day one. Thank you for diligently maintaining these observations. And now you have Adam Wilt on board.

But as for the photo, the shift to cyan behind the branches seems like it's cast over other parts of the image as well.

Although confirmed it's not normal behavior with other cams, somewhere else I've seen it before. I think my original JVC GR-HD1 may have had this tendency.

Anyway...you're on the right track.

Regards,
Tom

Piotr Wozniacki March 5th, 2008 09:15 AM

Tom,

You're right about the cast. To prove it doesn't matter, I have posted above another grab with totally different colours (more red than cyan), and with the sky area only in one corner (as opposite to the previous ones where the sky dominated the scene). Still the same behind the trees...

I am totally aware the white balance (or colour matrix) is not neutral in either of the grabs, but - being opposite to each other - it shows my point that you cannot avoid the abrupt clipping with bluish patches (unless carefully watching and adjusting your exposure just for that, which is not practical).

And one more thing that needs stressing: this phenomenon - while easily explainable using laws of physics - is in fact very annoying and ugly. In other cameras it's handled in a fashion more pleasing to the eye. Why it is different on the EX1 beats me; unfortunately - while a bit safer like Adam says - the Cine gammas do NOT completely get rid of it at all. In fact, I just did some more tests with the safest one, the Cine2 (said in the manual to safely compress the highlights) - and while indeed the picture never even touches 100 (the zebra at 100 never shows up), the trees against the overcast, grey sky still create the artefacts around them.

I'd like to kindly ask knowledgeable people like Bob, Bill or Alexander to stop preaching that this is normal, and instead post their own examples of the phenomenon. I can't understand how people can leave with this - the clipping algorithm implemented in the EX1 is flawed IMO. It just seems unable to clip precisely around the very edges of darker (unclipped) objects, which are instead surrounded by ugly patches of unclipped sky... If this is how "broad dynamic range" is supposed to manifest itself, than no thanks - I prefer narrower range as in the V1E, or any other prosumer camera for that matter.

Yes I know the EX1 is capable of producing stunning pictures - I have shot lots of them as well, but only in very favourable or controlled lighting conditions (outdoors, with foreground lit generously against dark blue sky, or the opposite extremum: indoors, with low but controlled lightning). But in such conditions, even the HC1 I used to have is able of creating breath-taking imagery - and we're talking CineAlta here!

Unless my camera is indeed faulty, which only some examples from other people could help me to determine.

Steven Thomas March 5th, 2008 11:28 AM

Again,
I bring up Adam said this in his ORIGINAL review. It was brought up earlier in this thread maybe three times! Why bash on others for your problems. It's not ours.

Even Adam himself said to stick with the Cine curves during those shots.

If I saw this over exposure condition happening when composing the shot, I would readjust for the shot just like adjusting everything else, focus, aperture, focal length...ect..

Piotr Wozniacki March 5th, 2008 12:27 PM

Quote:

Originally Posted by Steven Thomas (Post 837777)
Why bash on others for your problems. It's not ours.

Steven, with the above you're bashing me. Also, if this is not your problem - why post here at all?

Quote:

Originally Posted by Steven Thomas (Post 837777)
If I saw this over exposure condition happening when composing the shot, I would readjust for the shot just like adjusting everything else, focus, aperture, focal length...ect..

Bullshit. None of the above can be considered overexposed, if the main subject was the foreground. They may show other settings' flaws (I was experimenting with WB / colour matrices extrema while taking them, NOT looking for the "abrupt clipping"), but certainly they're not generally overexposed! A "narrower latitude" camera ((like the V1, grabs of which I posted earlier in this thread as the comparison) would simply blow-out the sky; the EX1 blows it out partially as well, while leaving nasty patches around the contrasty objects. If you can't see this obvious flaw, see the optician.

If you still don't follow, I'll repeat it for you, Steven: with certain completely legal exposure levels, required to bring out darker foreground, the EX1 has problem with the compression algorithm, leaving unclipped boarders of bluish tint around darker objects where it should be blowing out like elsewhere in the sky (further away from these objects). It does so with all gammas; the cine gammas are only safer in that with auto iris this doesn't happen. But use manual iris to bring out some underexposed areas, and you can see the same "abrupt clipping" it does with standard gammas, even with auto iris on.

Did you understand now? Good, as this was my last effort to politely address your taunts.

Steven Thomas March 5th, 2008 01:19 PM

Piotr,
Have you happened to notice that you are really the only one complaining about this?

You wrote:
"Bob, Bill or Alexander to stop preaching that this is normal, and instead post their own examples of the phenomenon."

Maybe you're right, I'll let them speak for themselves, but I'm certainly under the impression they are not having issues, therefore, not going on with this rant.

Bob Grant March 5th, 2008 04:02 PM

As I suspect I'm one of the mentioned parties all I can say is the request to post our own examples borders on the absurd.

I can make an aircraft fall out of the sky without exceeding any of the acceptable control settings but it's not something one does more than once. This is why aircraft and many complex pieces of technology have an "envelope" of operation. It's why simply memorising a flight manual doesn't qualify you for a pilots licence, it's why memorising a camera manual doesn't make you a cameraman. It is why experience is everything.
Fortunately with a camera mistakes aren't as bad as they are with aircraft, automobiles and guns. The same logic still applies though, make mistakes by going outside the envelope and learn from them, yes there's not a lot published about where the limits of the envelopes are for each camera but then again we don't have air safety investigators studying smouldering piles of twisted metal like we do with bad images. So we have to learn from our own experiences.
Last night I shot a performance with my EX1, without even downloading the clips I know a lot of it is going to be crud. The camera did nothing unpredicatable, I operated it as well as it could be, the camera (heck any camera) simply could not cope with the flickering lighting, the very video system itself could not cope. For the record ultimately this was my mistake. From experience I now know that I should never of even agreed to attempt the shoot. Will I make the same mistake again, probably, I'm a sucker when a friend asks me to do something. Will you find me here posting examples of the crud I shot with 'please explains', good grief no.
So what would a professional have done if asked to shoot this. He would have insisted on two trucks and a crew of 10 to light and shoot this. Now he might have gotten away with it without that, just as I might have too. But I didn't and that's the difference between me and a professional. I take the risks and sometimes fail spectacularly, professionals don't, and I and the professional bill the client accordingly.

Now I know what a certain someone is thinking. "I didn't have these problems with my other camera". Well for sure. Learn to fly a 747 and you'll likely never have to worry about compressor stall like you will in a F18. That's why pilots get licences that are "qualified" for certain aircraft. It also shows that things built to extract more performance are also riskier to use, they take more experience to learn the dangers of, they are not easier, they're harder to work with.

It seems to me that the underlying false assumption is that because this camera has 'more' of this and 'more' of that it'll be easier to use. Wrong.

It might also explain why camera manufactures haven't unleashed the beast in their cheaper cameras in the past.

Piotr Wozniacki March 5th, 2008 04:28 PM

Quote:

Originally Posted by Bob Grant (Post 837879)
Last night I shot a performance with my EX1, without even downloading the clips I know a lot of it is going to be crud. The camera did nothing unpredicatable, I operated it as well as it could be, the camera (heck any camera) simply could not cope with the flickering lighting, the very video system itself could not cope.

Bob if your intention has been to address my problem by drawing a parallel then I'm afraid it failed, as I am talking about perfectly normal conditions, which "camera (heck any camera) simply should cope with" ;)

Quote:

Originally Posted by Bob Grant (Post 837879)
It seems to me that the underlying false assumption is that because this camera has 'more' of this and 'more' of that it'll be easier to use. Wrong.

I'm NOT making such assumptions; to the contrary - as a technical and cotrol freak rather than a creative videographer, I'm excited with the level of complexity this camera presents. I like it difficullt!

But a common sense tells me that while it indeed can do more (not necessarily easier), it should be doing the easy and obvious stuff no worse than other, lower-end cameras.

If you like analogies, a 1001 HP Bugatti Veyron can perform the same way as an average, 95 HP family car, but not vice versa. This camera even has the green button; never tried it but I'm sure that other than with perfect lighting, it cannot produce as good pictures in the "idiot-proof" mode as HC1 can, due to the effect I'm talking about. Do you think it's just OK?

Benjamin Eckstein March 5th, 2008 05:52 PM

Maybe for the sake of everyone's ego, temper, etc. this thread should be closed? Chris? It seems all points have been made and there is just a lot of bashing.

Bob Grant March 5th, 2008 06:34 PM

Quote:

Originally Posted by Piotr Wozniacki (Post 837892)
Snip...
Bob if your intention has been to address my problem by drawing a parallel then This camera even has the green button; never tried it but I'm sure that other than with perfect lighting, it cannot produce as good pictures in the "idiot-proof" mode as HC1 can, due to the effect I'm talking about. Do you think it's just OK?

Yes, I think it's OK.
And I think that's what many of us have been trying to tell you.
That's why I'm glad I can and still do still use a PD170.
Perhaps one day I'll truly master the EX1 and I will not need to use a 170 anymore.

Should I point out that the Veyron comes with a selection of keys?
You don't give the red key to your teenager children.

Nick Williams March 6th, 2008 01:21 PM

Hi,

It looks like this may be a discussion that I really have no business being involved in, but the title of the thread seemed appropriate for my question.

I shot some timelapse video this morning of the sunrise with an ex1 using some settings I downloaded from another thread here, I believe from Bill Ravens-

PP3: TC2 C1

To put it simply, I was curious to see what kind of gradient I would get as the sun came up. When I was playing back the footage on my macbook pro I noticed if I tilted the screen to an extreme degree, I saw 3 very distinct levels of color rising up from the mountains. But I really could only see that clearly by tilting my screen. I opened the file on my macpro and it definitely wasn't as prominent on this monitor, but I knew it was there.

My question is, is there something that can be adjusted to make the transition between these brightness levels maybe a little more gradual?

To show you guys I've adjusted the levels to make it easier to see what I'm referring to:

the adjusted movie clip here:
http://www.alienbedroom.com/timelaps...e_adjusted.mov

original movie clip:
http://www.alienbedroom.com/timelapse/timelapse.mov


any info on this would be appreciated! or I'll happily move to another thread too.

thanks
nick

Steven Thomas March 6th, 2008 01:26 PM

Nick,
Using time lapse, this has been brought up before. I'm not sure why there's banding, but it's been seen before in the time lapse footage. I image it has to do with bit rate, anyone?

Bob Grant March 6th, 2008 05:51 PM

Quote:

Originally Posted by Steven Thomas (Post 838366)
Nick,
Using time lapse, this has been brought up before. I'm not sure why there's banding, but it's been seen before in the time lapse footage. I image it has to do with bit rate, anyone?

Probably more to do with bit depth. This is an ongoing problem even without a camera when you try to wrangle images created with large bit depths into video with lower bit depths. I've seen some really ugly results from gradual gradients created in Lightwave when the sequence was bought into a NLE. The camera is trying to wrange 14bits per channel RGB into 8 bits. Banding and colour shifts at the bottom and top end of the range are to be expected.

What I suspect could be happening is the camera has been designed as a 10 bit system for the HD SDI output. The easiest way to get from 10 bit to 8 bit is to simply discard the two LS bits. This is does leave some issues that can be solved by dithering however dithering is adding digital noise, the last thing you might want in a mpeg-2 recording system.

We do have a SD SDI CRT monitor, I haven't seen how the SD downconvert from the EX1 looks on that but someone who has tells me it looks fantastic. It might be interesting to compare the signals coming out the SDI port to what gets recorded.

A lot of us were sceptical that Sony were truly sending a full 10 bit signal out the SDI port. Well maybe we've got want we wanted and might to some extent be loosing out in other areas. If it really is 10bit HD SDI I can see an expensive little box on my wish list. I'm not buying any 16GB SxS cards as yet, rather put the money towards a 10bit 3rd party recorder.

Nick Williams March 6th, 2008 08:02 PM

I see, that makes sense. So we might possibly see better results coming out uncompressed. Thanks for the insight guys.

Steven Thomas March 6th, 2008 08:18 PM

Actually,
The banding occurs during the time lapse footage, using the normal recording modes there's no issue. Well, other than the 8bit gradient capability itself.

Maybe someone will jump in to explain why this happening with the time lapse mode. This has been brought up before with image samples.

Steven Thomas March 6th, 2008 08:21 PM

Quote:

Originally Posted by Nick Williams (Post 838549)
I see, that makes sense. So we might possibly see better results coming out uncompressed. Thanks for the insight guys.


Since the SDI is 10bit vs the in camera 8bit and Sony is utilizing all of the SDI 10bits, this would offer smoother gradients. But, since this particular banding is present in the time lapse and not normal record mode, I'm not sure how the time laspse will look via SDI.

Nick Williams March 6th, 2008 08:41 PM

That's true, I figured that if an uncompressed signal may fix the banding issue that it probably wouldn't fix it on the time lapse side. I don't shoot a lot of sunrises or anything, so it shouldn't be a common problem for me.
But say that was the result of shooting normal speed.. would I adjust the knee or slope? To try and smooth those together? I'm just not familiar enough with those settings to know what to adjust. I guess if I wasn't shooting so close to blow out, that might help too.

Piotr Wozniacki March 7th, 2008 07:08 AM

3 Attachment(s)
OK guys - back to the topic. I had a sunny day today, so - after my trials with trees againt gray clouds - I made some tests with beautiful, deep blue sky this time...

The 3grabs show the same scenery with:

- STD1, knee manual at 95
- CINE4 (unfortunately - still some "abrupt clipping", Adam !)
- CINE2 (this one IS safe, but really very, very flat - see the next post).

Piotr Wozniacki March 7th, 2008 07:12 AM

4 Attachment(s)
And here is some more comparison:

- STD1 with auto knee, against
- safe CINE2

Obviously the auto knee seems to be doing better than manual at 95 (though this test is far from scientific, as the scenery is not identical - even more backlit; this made the zebra appear and allowed for iris adjustment while shooting). Therefore, below is again:

- STD1 knee manual at 95 (sorry the picture has wrong name - it actually IS manual at 95, not auto!)
- CINE2

Can you see the aureole around the roof and trees with STD1? And there was not even a trace of zebra there while shooting !!! Do you understand now why I think it's not good at all, and would do with some similars grabs of yours to compare?

The only gamma free of it is CINE2 -- but how flat it looks!

Go figure...

Tom Roper March 7th, 2008 09:41 AM

Hi Piotr,

Just of few observations I would make, you may want to choke me for saying them, but they are my honest impressions, and a little more general, a little less specific.

I think std 1 auto knee 2 is clipped in both the luma and chroma channels. The exposure of this scene breaks the dynamic range. My judgment in this case is that cine 2 looks flat but only by direct comparison to cine1. On its own merit for video, (not a screen shot), I think it actually still remains on the margin for oversaturation in the chroma channels, and quite contrasty.

Std1 auto knee 2 is more excessive. Look at the blue cast in the shadows, and the color shift on the bricks. The gray and pink sunlit bricks turn to blue and purple.

I think it may be possible to increase the luma exposure in cine 2 to bring out some detail in the shadows, and not clip the highlights. Cine 2 shows less tendency to clip the chroma, thus the colors do not shift as radically when transitioning between sunlit and shadow areas in the midtones (i.e. the bricks).

I think there is excessive chroma saturation in all the screen shots. What that does is open the possibility for colors that bleed at the edges. I see some of that in your pictures. Your EX1, while being noted for lower CA than my XH-A1 for example, is nonetheless overemphasizing the CA that is there. Look at the edge along the roof gutter on the right in cine4.jpg, and along the gutter and rooflines at the upper left in std 1 auto knee 2.jpg.

One characteristic that distinguishes Canon's ugly red/green fringing from Sony is that Sony's fringing when it does appear, is purple/bluish/green. I think it is preferable usually but works against you when the backdrop is a blue sky. And some of the hue shift at the point of highlight clipping in the area of the branches may actually be minor CA that is overemphasized or clipped due to an overall oversaturation of the color channels. In other words, what begins as a minor optical blue fringing, when oversaturated in the chroma channel bleeds over into an amorphous bluish blob against a clipping sky highlight behind. I think I see minor blue CA that in some areas of the picture is clipping into prominence by overall high gain or saturation in the chroma channel.

...that's what it LOOKs like to me. You have the camera and vectorscope displays, so I may be all wrong, just sharing my visual observation.

Speaking on a personal preference, I very much like high contrast, color saturated images. And I have my XH-A1 presets set up for this generally. It may even be more "forgiving" in the sense, of color or exposure latitude. It does seem to more gracefully handle exposure/chroma gradients in the type of high contrast, bright outdoor scenes that you are testing. But that said...I believe the recent pictures above from you take contrast and saturation a bit too far. If it was me, I would try and go back to a baseline, decrease the saturation and dynamic range, and see if there is a decrease in the tendency for the colored highlights to bleed, and perhaps with that, the abrupt highlight clipping. I think you can still do that and still retain saturated high contrast video with punch. I think it can be a mistake to make too many judgments from side by side still images. As an anecdote, I used to sell hi-fi speakers as a junior, doing A-B listening comparisons. Invariably, people would purchase the "louder" sounding speaker even if the sound coming from it was colored. We can make the same mistake when doing A-B's on still images coming from a video camera. In my own work, (which is more play than work since it's hobby, not occupation), I constantly compare my video to video from others, Discovery HD Channel, HDNet, CBS etc. The eyes can fixate on something wrong, and overcorrect for it. Extended viewing of a broad range of material, visuals and sounds are what prevent fixations.

My judgment is that your colors are extremely vivid, to the point of imparting color casts in various parts of the image. Again, refer back to the bricks. It's not just a white balance issue. It's a case of shifting balance, bricks that show the correct color in the sun, taking on a hue in the shadows. I can't tell you what to do, only what I would do. And if it was me, I would try re-doing some of your tests at lower color saturation gains. Just my $0.02

Tom

Tom Roper March 7th, 2008 09:51 AM

Just to add...


In the old days of film, we used to call color shifts caused by under or over expsoure "reciprocity failure." That's how I would describe std1 autoknee 2.jpg.

It works both ways, color shifts due to under or over exposure.

Louder isn't always better.

Michael H. Stevens March 7th, 2008 10:05 AM

Piotr:

I think with all these pictures you are trying to sell your beautiful house!

Seriously, forget CINE2 unless for broardcast, you know it is just CINE1 truncated. For bright scene like you have shoot show us CINE1 or 3. I too was thinking why does everybody go HiSat. I have found on my scopes that the blue often clips when the luma is fine and HiSat makes this worse. Try C1 & 3 with normal or cinema matrix.

Mike

Piotr Wozniacki March 7th, 2008 11:10 AM

Tom and Mike,

Thanks for your comments. You're absolutely right - these grabs were taken from my experimental shootings with PPs varying in the gamma used, but having all the same, highly saturated colour matrix. Even though I do like it contrasty, rich and juicy, some of them are indeed oversaturated even to my eye, and I have since modified the PP's accordingly.

However, with deep blue sky it was not that easy to clip the highlights as it was with dull wheather and overcast sky, so I made it more difficult for the camera by increasing the chroma... And the peculiarity of "abrupt clipping" appeared again - even with the Cine4 that Adam recommended as safe in this respect. Only Cine2 seems completely safe (at least as luma is concerned - chroma can still be clipping, as Adam pointed out).

Well, I guess I also owe some positive comments to this machine: were it not for abrupt clipping, the contrast range and colour saturation could be really considered absolutely fantastic. What needs to be said is that even with this level of colour gain (+25 with the Hisat matrix) as well as detail amount present, there is almost no mosquito noise or other artefacts that with the HDV codec on my V1E would have spoiled the image completely.

PS. Just received an e-mail from Adam with a couple of invaluable remarks and observations. One of the most important is that with Cine2 - even though it's safe in that its luma never exceeds 100% - the chroma is clipping nevertheless in the high 90-es. So, beware of that! This confirms your comments about the chroma (especially blue channel) clipping, which I can also see in Vegas scopes.

I will be trying now the Cinema matrix.


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