abrupt highlights clipping

[Leonard Levy]

Randy, Like I said I've never gotten used to it, but I figure if I can't see the relative distribution of pixel brightness than I am blind - it should be obvious in my viewfinder.
What i want to know is specifically whether a certain area is over 100%. If I'm looking at a shot with clouds, I may know some of it will hit 100, but what about the white shirt of my talent, or on an interior similar questions. I may know I've got a window or something bright somewhere,m the question is only whether something I care about specifically is white.

But if it works for some of you great.

[Simon Hunt]

You guys are going in a lot of different directions with this discussion.

First of all let me say I do not own an EX1 (yet). But I have over 25 years of broadcast and Film/TV production experience (look me up on www.IMDB.com). Most recently I have been doing TV Movies and TV series using the "Panavision-ized" Sony F-900. This camera is part of the "cine-alta" line as well and has a lot of the same adjustments as the EX1. The main thing I have learned is that you can EASILY bury yourself with these adjustments if you don't know what you are doing (and even if you do). The type and range of adjustment described in the EX1 manual is very similar to the F-900 and you have to remember that these adjustments "overlap" each other in many areas. This means it is very possible to create an "undesirable" looking picture with a combination of extreme conditions and a poor choice of menu settings, so you have to be careful. I call it "death by a thousand knobs". Do a lot of testing and experimenting if you are not familiar with these menu settings. The preset looks are best to use if you do not understand how these settings interact with each other. That's what they are there for.

As far as white clipping goes, my experience is with waveform monitors and zebras and not with histogram. I'm still learning if histogram is useful for me. Keep in mind these are 3 different TOOLS to help you evaluate your exposure. Choose which one (or combination of them) works for you. Zebras don't do anything except tell the operator what part of the image is exposed at what level, that's why 1 of them is adjustable, so you can choose what information you want to see. The "center IRE percentage reading" option looks like something I would like to use, especially if you don't have the luxury of an on set waveform monitor. As far as the 100 and 108 IRE confusion goes, this is my understanding of it. 100 IRE is "Video White". Cameras can capture up to 108 IRE to preserve detail in "white" or overexposed areas. Most broadcasters will "clip" thier signals at 100 IRE, so you have to decide in conjunction with your post-production people (or broadcaster) which setting is best for your situation.

Auto Knee and Knee point/slope/saturation adjustment is useful if you are careful. Auto knee is best for the inexperienced as the camera circuitry does the work for you, but only to a limited amount. Bright sky can be controlled SOMEWHAT by adjusting the knee point and slope, but I would only attempt it with a professional monitor and waveform available. Knee saturation can bring back color detail in the part of the image that is being controlled by the knee point/slope (This probably ties into Adam Wilt's comments in his review, in my opinion). This means that a sky (or windows) with puffy white clouds and patches of blue sky SHOULD be able to be exposed properly using a combination of these settings. Remember that the access to "professional" settings means access to "professional" problems!

If all else fails and you feel like you get lost in these adjustments then reset back to factory defaults or go through the manual and set all the menus back the the default setting listed in there.

I hope I've helped and not confused the issue more!

Simon Hunt

[Leonard Levy]

Randy, The reason I see little value to a histogram is that if I don't know the general distribution of lights and darks, I figure I must be blind because you can see it in your viewfinder.

What I want to know in any situationn is exactly where am I over 100 and losing detail or where are my flesh tones falling. In many images I expect that some spots will be over 100 but I need to know if its my subject's shirt for example, or the paper on the table.

It just seems to way to vague to spend much time worrying about.

Michael, most zoom lenses lose some exposure when you zoom in , just watch that when you take spot reading through the lens. It will be obvious in the viewfinder and you can try to avoid zooming all the way or learn to adjust a bit.

[Warren Kawamoto]

Originally Posted by Michael H. Stevens

I thought this lens surely to be constant f. Can anyone confirm?

Look here.
http://provideocoalition.com/index.p..._camcorder/P3/

Apparently, actual light transmission ramps from 1.9 wide to 2.8 telephoto although the f stop indicator reads a constant 1.9. If that's the case, you're opening up a little more than a stop if you zoom in, lock your exposure, then zoom out.

[Michael H. Stevens]

Yes true. When I spot focus I always check the LCD after zooming out and often make corrections. Been out today shooting and as an experiment I did everything by eye - IE just getting the LCD to look as close to the scene as possible. It's a good little screen and I'm looking forward to sitting down at the computer with a bottle of claret tonight and seeing how i did.

I think I have solved the problem with the histogram. It is too small and its vertical exaggeration is too great. There can be value along the x-axis going into clipping which are indistinguishable from the axis it's self. IE There is clipping that is too small to see. Funny thing today - I was filming birds on a fishing pond and I saw the histogram and thought it was a swan.

[Randy Strome]

Originally Posted by Michael H. Stevens

I think I have solved the problem with the histogram. It is too small and its vertical exaggeration is too great. There can be value along the x-axis going into clipping which are indistinguishable from the axis it's self. IE There is clipping that is too small to see.

You are absolutely correct. If Sony does not offer an enlarge toggle to the histogram button (off-on-enlarge) in a firmware revision, I hope they will remove the static axis line. It is not required, and its removal would make a reading to the furthest right that much more noticeable.

[Bob Grant]

Vegas lets you view a waveform monitor and a histogram at the same time. Using that with some generated media is a good way to get a grasp of what a histogram does. One thing to read an explanation, another to watch it happening in a controlled manner.
Based on my own experiments a histogram can be quite misleading, an overexposed white wall yields a single line on the RH edge of the graph. It's doing exactly what it should as all pixels have the same value.
How to use that. If you want to avoid clipping start from underexposed and watch the histogram as you open the iris, this way you can see the brightest area moving into clipping. Starting from the nice gaussian blob in the middle may tell you nothing, going back to Piotr's original shot that mountain in the middle would be the dark foreground while the sky is a single line on the RH side of the graph.

[Piotr Wozniacki]

Originally Posted by Simon Hunt

Remember that the access to "professional" settings means access to "professional" problems!

Simon, as the author of this thread I couldn't summarize it better myself; good point!

And it's good to know we have "professional" problems, isn't it? Much nicer feeling than the simple "oh, this camera was supposed to perform better" type of frustration...

[Piotr Wozniacki]

Worked all weekend hard, and have some good news to share (frankly, wasn't sure whether to put it here, or in the "Picture Profiles" sticky - but who cares; everybody here reads every thread anyway, don't they).

Well, so I've set up some basic PPs for the most typical shooting scenarios (PP1- PP4 using the Hisat matrix with slightly differing settings):

1. PP1, based on the STD1 gamma (for indoors, low light/low and dull scenery)
2. PP2, based on the STD4 gamma (for indoors, low light but contrasty scenery)
3. PP3, based on the CINE1 gamma (for outdoors, high light but flat scenery)
4. PP4, based on the CINE4 gamma (for outdoors, high light, contrasty scenery).
5. PP5 (for outdoors low light flat; TBD)
6. PP6 (for outdoors low light backlit/contrasty; TBD)

The indoors presets - even though based on the STD curves and Hisat matrix - have no problems with highlight clipping, as I'm using them for real low light (just regular home bulbs) situations, thus no highlights to clip (OK - the punchy STD1 does clip to pure white, but only the bulbs themselves, with no artefacting around them, anyway).

The outdoors presets - even though based on Hisat matrix, as well - also do very well. In order to avoid that ugly phenomenon discussed in this thread, the following must be observed:

- unless the scenery being shot is really low-contrast, engage PP4 and not PP3 (see above), as its CINE4 starts compressing much earlier (65%) than the PP3's CINE1 (80%, according to Adam Wilt)

- if in manual iris mode, with zebra set to 100%, never allow ANY zebra in the sky (some traces only allowed in pure white areas, like birch barks; the sky - even cloudy - is NEVER pure white so NO zebra there!)

- if (for any reason) in auto iris mode, increase the TLCS Speed in the menu; when entering clipping, the intermediary stage before iris closes enough (when the ugly aureole around the contrasty shapes is likely to occur) will last much shorter, and be less noticeable

- if shooting a scenery which is likely to exhibit this behaviour for longer time (stationary), I've found out that the halo may be minimized if the offending object (trees, most typically) is in PERFECT focus; rarely practicable, I know - just a side note.

When my PP1 through PP6 are fine-tuned, I'll put them in the "Picture Profiles" sticky for you to check.

PS. I'm becoming to love this camera; if only the ND filter switch didn't stick!

[Alexander Ibrahim]

Originally Posted by Piotr Wozniacki

if in manual iris mode, with zebra set to 100%, never allow ANY zebra in the sky (some traces only allowed in pure white areas, like birch bark; the sky - even cloudy - is NEVER pure white so NO zebra there!)

Good work, and good post Piotr.

The snippet above is in my opinion the most important part of your post- and a rule you have to know when and how to break.

This fundamental technique is central- basically you never want more than 100 IRE in your image anywhere- ever. Of course half your data is in the region close to 100IRE so you want to always push against this rule. You usually want your highlights over 95 IRE.

Shooting in the real world sometimes means compromise. What's worse... having the "halo" or having your actors entirely in shadow? Sometimes you break the 100IRE rule because otherwise your image doesn't work. Just don't ever do so lightly.

This is why I earlier talked about exposing. Its possible some thought I was being condescending... but its important enough I want to repeat myself.

Don't start trying to solve problems with PP's or other "technology."

Start with the time honored techniques of the cinematographer's craft. Remember that lighting is about control of light and shadow not merely illumination. This issue is an example of the need to learn to place a shadow in a portion of the image. It is also an example of an issue that is solved best on set- because once you capture that "halo" as data getting rid of it in post is hard.

Here are some solutions that have worked for me in the past.

Use graduated ND filters to eliminate over exposed areas. A rotating filter box is important so you can move the filter to affect just the area in need of adjustment. Beware of internal reflections!

You can also use half nets close to the lens, like you would use a half scrim in a light. This is harder to achieve in practice, so definitely try to graduated ND first.

Use lighting to lift the exposure of your subjects. You can lower total exposure by essentially eliminating contrast.

For the effect under discussion a polarizing filter can eliminate or soften the effect. Its easy and worth a try. I'd guess it works about 25% of the time.

Only once you've tried the photographic methods should you turn to the technology to do fix the image. The technological tools we have today are better suited to enhancing the creativity of an image than to basic control- even for cameras that shoot RAW like RED.

Acquiring in a higher quality codec will help. Chroma subsampling is not the key issue in this particular case, though it certainly wouldn't hurt. Mostly you want a 10 (or higher) bit codec. Such codecs have more ability to handle "superwhite" and "superblack." This is the best technological "magic bullet."

Finally the camera has controls in its picture profiles to help solve problems like this. I don't like to use them because as we have already seen these settings can cause their own problems. Sometimes the cure is worse than the disease!

The good news is that the experience you gain on the EX1's picture profiles will be valuable when shooting SI2K, RED, F900 or other cameras with extensive controllability.

[Piotr Wozniacki]

Thanks Alexander for your favourable response. Definitely - the most rudimentary, photographic rules & tools should have priority over the numerous tweaks, available in this marvellous camera. Also, I will certainly think of investing in a mattebox with filter holder, because the grad ND filters (and possibly polarizers) seem indispensable.

The higher the potential of a tool one is using, the higher his demands on the quality of work he is doing. And this is perhaps one of the most important advantages of this camera - raising expectations, and motivating to fulfill them. But of course, purely technical benefits like the marvellous low-light performance, manageable DOF etc are also important!

[Alexander Ibrahim]

Originally Posted by Piotr Wozniacki

Thanks Alexander for your favourable response.

You are most welcome.

Definitely - the most rudimentary, photographic rules & tools should have priority over the numerous tweaks, available in this marvellous camera.

I keep saying that in great part to remind myself its true! I am such a tech geek that sometimes I forget this simple fact.

Also, I will certainly think of investing in a mattebox with filter holder, because the grad ND filters (and possibly polarizers) seem indispensable.

I bet there is a thread for that and the EX1 somewhere- but please drop me a line when you pick a mattebox- or if you end up starting the thread.

The higher the potential of a tool one is using, the higher his demands on the quality of work he is doing. And this is perhaps one of the most important advantages of this camera - raising expectations, and motivating to fulfill them. But of course, purely technical benefits like the marvellous low-light performance, manageable DOF etc are also important!

Well said.

[Michael H. Stevens]

When Alexander said: "Acquiring in a higher quality codec will help. Chroma subsampling is not the key issue in this particular case, though it certainly wouldn't hurt. Mostly you want a 10 (or higher) bit codec. Such codecs have more ability to handle "superwhite" and "superblack." " does he mean acquiring like with Cineform NEO-HD?

[Bob Grant]

I think ideally you want a 10bit recording medium and the only way to get to the 10bit output from the camera is from HD-SDI port and all the options that could be used in the field are rather expensive.
Once encoded to 8 bit on the SxS cards most NLEs can handle the super whites and blacks. Vegas certainly doesn't have any issues with them although most delivery formats might. Only a matter of wrangling them and there's a number of ways to do that.

[Michael H. Stevens]

Originally Posted by Bob Grant

I think ideally you want a 10bit recording medium and the only way to get to the 10bit output from the camera is from HD-SDI port and all the options that could be used in the field are rather expensive.
Once encoded to 8 bit on the SxS cards most NLEs can handle the super whites and blacks. Vegas certainly doesn't have any issues with them although most delivery formats might. Only a matter of wrangling them and there's a number of ways to do that.

So are you saying Bob, that while editing and preview is easier the quality using the NEO-HD codex from mp4 to avi is no better than the Sony mp4 to mxf?