108%
 

Hi all,
I had inquired about this deep in another post but thought I might seek a definitive answer here.

What is the nature of the info being recorded in the whites above 100% on the zebras or on the brightness indicator?

Thanks

The recording can retain detail up to 108%. Broadcasters often want the upper limit to be 100%. There's some flexibility with that. In USA, PBS tends to be the most restrictive.

In post you can "color correct" to lower the peak but keep the detail.

Cine Gamma settings can impact how the camera handles such peaks too. Cine 2 limits things to 100% I believe. The advantage of using this if your target is broadcast is that the Gamma curve rolls it off to some extent rather than a hard clip (in theory at least).

I really, really, really wish Sony would provide accurate examples of how Std and Cine curves work though. My ideal would be a "test scene" in which one could use to create Picture Profiles with some accuracy.

This camera has such great capability but it seems you need become a member of some secret society before anyone will reveal the secrets of how to use it. The Sony user manual is no more than a list of menus. Who will write the real manual?

I think this is the secret society.

no real secret here, but as this camera is tagged "cinealta", it's part of the pro camera from Sony.
You will find on it almost all settings you would find on a F900, F23 or Genesis. You're not working with a consumer or prosumer camera, even if it have the same size.
If you want to use it at its best, you will have to get strong knowledge on video internals, action of gamma curves, highlights managements, codec artifacts, datarate and so on.
If you want more detailed information on some settings of the EX1, search for Sony F900 manual. You will find a lot of similarities.

You can also purchase the DVD "hands on Sony EX1".

In my "mapping" the PP for my EX1, I explored various EX1 gamma presets, including the 8 STD and CINE choices. I had the EX1 connected to HDRACK; and, I monitored the Waveform Monitor while observing a gray step with the camera. It seems clear to me that the difference in Gamma presets are primarily the position of the knee of the gamma curve. By adjusting the gamma LEVEL, one can move the middle gray up or down on the WFM. Gamma LEVEL seems to be, essentially a black stretch or black compress slider. I suspect the gamma presets are nothing more than various settings of gamma level and black.

Now you got me interested Bill; so you're saying that the EX1's direct counterpart of most other cameras (like the V1) Black Compensation (stretching/compressing) is *ANY* Gamma curve's Level, and *NOT* the Black Gamma and Black settings combined?

Black Gamma is the equivalent of Black stretch/compress on other cameras.

-gb-

I'd also tend to think so, Greg. Looks like we're now having two differing opinions - I'd really appreciate clarifying this! Not having a WFM, it's good to know the theory while playing with the multitude of settings...

Okay, let me clarify a bit, Black Gamma on the F-350 is as I stated. I don't believe Sony altered the function of that setting for the EX-1. I don't own one though, so I welcome any proof to the contrary.

-gb-

Yeah...I guess a proof could be experimenting with the proper equipment, or some white paper from Sony. I guess the early EX1 adopters deserve some more than just the manual, which is written in a very simplistic way, to say the least.

Any chance of getting some info straight from Sony?

In my observations, BLACK sets the endpoint, BLACK GAMMA sets the tangent thru the endpoint or slope, and Black Level sets the knee position. This is a reasonable approximation of what I'm seeing on the vectorscope.

If this is so Bill, please tell me: to compress blacks, one should crank lower BLACK and BLACK GAMMA (the black knee point is seelf-explanatory). Do I take it right?

Piotor...

Compress the blacks...dial gamma LEVEL down.

Bill,

You mean any gamma curve will compress blacks with its level down? Or just the BLACK GAMMA?

Piotr...

I'm getting confused. I refer strictly to the Profile menu settings for the EX1. BLACK effects only the master black level.

On page 75 of the US Owner's manual....very top of the page are the Gamma settings: LEVEL(-99>0>+99) and SELECT(STD1,2,3,4,CINE1,2,3,4). I refer to the LEVEL setting...negative values compress blacks, positive values stretch black. Note that the reference level at zero, changes according to which Gamma SELECT value you pick.

All this is fine Bill (my EU manual says the same ;)). BUT, there is a separate BLACK GAMMA setting (regardless of which gamma curve you select), and I thought THIS is responsible for the black compensation. Hence the confusion...

The BLACK GAMMA setting is an unknown. The manual says it affects the noise level in the black areas. It did not seem to greatly affect the black level or knee position when I adjusted it while connected to a WFM.

That is correct. I believe what Bill is looking at on the gamma curves page may be an adjustment on the bigger cameras called master gamma. This will shift the entire gamma curve up or down without changing the shape of the response (like a positive or negative bias).

Black Gamma compresses/stretches the blacks.

Then there will be settings for black as Bill indicated that set up the start of the lower knee known as pedestal. Then there will be one that sets the minimum black level known as set-up. It's just that Sony has their own terms for these settings.

-gb-

What the manual means by that is you'll get less noise if you dial it down to crush the blacks.

Black Gamma is not unknown, it is Sony's stretch/compress adjustment.

regards,

-gb-

Greg...

Thanx for weighing in. Sony sure does confuse things with their esoteric nomenclature. You're right about BLACK GAMMA. Still, when adjusting GAMMA LEVEL, the entire gamma curve is shifted, in a much more dramatic way than with the BLACK GAMMA. GAMMA LEVEL does more than shift the entire gamma curve up and down. The endpoints, both high and low, remain unchanged while the midpoint moves up and down. To me, that looks more like a compress/stretch. For example, in the True Color calibrations I performed, I found a STD3 with a gamma level of 0 is equivalent to CINE1 with a gamma level of -40. There may be more going on with the shape of the curve, but this is true for the midpoints.

So - if I got your right, Bill - setting the GAMMA LEVEL (with any gamma curve selected) UP will make it more S-shaped, thus stretching blacks and compressing highs? And consequently, lowering the GAMMA LEVEL will compress blacks and stretch highs?

Well, this is how I understand your statement about the endpoints remaining unchanged, while the entire curve gets shifted up or down...

Anyway, your PP2 preset has both the GAMMA LEVEL (entire curve shift, CINE1 in this particular case), and BLACK (master pedestal) cranked down, which is what I'm after for low contrast / dull scenery...

I had a conversation much like this thread with Juan Martinez of Sony. He said he would try to get more info up on their website.

Sony PLEASE DO ASAP!

What we really need to see (IMHO) is a proper test chart and scope output showing EXACTLY how all these settings affect things.

Ditto; Amen.

Piotr..

yes, now you understand what I do.

Uff.. This is a happy end, as all the three of us (Bill, Greg and myself) were meaning basically the same.

Which doesn't invalidate Craig's call for Sony to come and clarify all down to the tiniest detail...

Ok, that's probably a better choice of words than I used. Gamma Level (called Master Gamma) is shifting the middle of the curve but what I meant to emphasize is that the 'shape' of that curve remains unchanged. I didn't mean everything from top to bottom as gamma is really defined as the alteration of mid tone response anyway.

The 'straight line region' more or less means excluding the knee and highlights as well as pedestal and blacks.

If you view the gamma correction as that 'bulge' in the middle which would be a straight line uncorrected, then gamma level simply makes that bulge move up or down, but doesn't alter the curve of the bulge.

Sorry for the vague wording.

-gb-

If it would be of benefit, I can take some screen grabs of the WFM, while looking at a 5 step black wedge under different gamma presets; and, post them here. Before I do it, tho', I want to know if it would be useful to anyone.

Absolutely Bill - it'll be a great reference!

Gamma on all video cameras refers to a control that moves the aproximate midpoint of the curve up or down. This will affect the shape of the curve - it has to.
The effect of high gamma is to make flesh tones lighter and bring up the low to middle end which gives a less saturated less moody picture.
It will compress the higher end but won't affect the areas near the top, so the main affect is to bring up mids and shadow areas. But it doesn't give your picture alot of character so people generally like to drop the gammas a bit.
Dropping Gamma tends to produce a more "filmlike image" saturated darker image even though that word probably has no technical meaning in this context. By the way on many professional characters lowering the gamma is done by raising the number on the menus. Usually runs between say 35 and 55 with 40 or so being average and 55 being lower.

However when you lower Gamma you might tend to crush the shadow area , so cameras started coming ourt with a Black Strech or Black Gamma to give you a control somewhere in the 20 IRE area ( that's just a guess on the IRE). So you can open up or crush your shadow area without affecting your actual bottom black level. Raising black gamma can increase noise and crushing it can lower noise, but you are also affecting your picture not just the noise. Ex doesn't have bad noise to me so I would just go by what l wanted to see.

The Black Level or Pedestel is simply the bottom of the picture - Capped black level. When you raise or lower either gamma this stays the same and everything else stretches or condenses against it. They settings will all affect each other though. When you say raise the mid Gamma it will pull the shadows up all the way from the Black level, but you could pull them down again with Balck Gamma and maybe affect the mid gamma or stuff right beneath it a touch.

( Are there 2 black level controls on the EX-1 like someone here said? - I didn't see that and would noit be familiar with that so maybe that's yet another wrinkle)

The Cine gammas add another wrinkle that is a bit of voodoo that some serious engineers don't like because the manufacturers don't like to post what they do.

I've been told that cine gammas use a modified knee function that is set to come in way earlier than the knee usually does. A tech I know said that some Panasonic cine gammas started working at 30IRE! This is just hearsay to me as I haven't tried to analyse them. However that's supposedly why you usually don't have knee settings on cine gammas.
(I'm open to hearing other interpretations and it would be nice if a Sony rep chimed in.)

I don't know the difference between the EX's cine gammas. maybe they all have the same basic cine gamma setting (the voodoo) with different mid and black gammas, or maybe they each have a different "voodoo setting"
Whatever it is, the cine gamma would of course change your curve shapes and modifying the cine gammas by altering the other gammas could start to make them similar.

Lenny Levy

The best thing to do if you want to know in which extent the GAMMA LEVEL or BLACK LEVEL work, you should simple put a graded chart (from black to white, left to right, linearily) in front of the EX1, and put a good HD-SDI oscilloscope to the hd-sdi output.
Then you will have a representation of the action of the gamma curve.
The Sony F900 have an internal shade you can select (like the SMPTE color bars) so this is more accurate. Maybe that's one thing we could ask for the next firmware upgrade...

In my knowledge, the black gamma setting is working somehow like the "knee" feature. knee is for the top of the curve, as black gamma is for the bottom.
The Gamma LEVEL stretch or collaps the gamma curve on itself.

As said earlier, you will have to work on both settings to achieve the look you want.

Sebastian, I did call up the internal color bars which one variant include a black to white strip. Alas the gamma curves don't seem to impact that.

Bill, why not use an 11 step or even a continuous black to white? I'm thinking of doing that myself.

Since I don't have HD-SDI to live scope ability I was thinking of just recording to card and dumping into Final Cut Pro. The internal scopes are at least reasonable.

Craig...

Yes, one could certainly do that for themself; and save me the trouble ;o)
The only thing to be aware of is that the absolute white and absolute black points on whatever you generate aren't guaranteed to be 0 IRE or 100 IRE.

When I do it, I use a DSC Labs Camette chart, which guarantees black and white very close to 0 and 100 IRE. Without the calibrated chart, you really don't know what value your pure black and pure white wedges are. I tried what you suggest, and trust me on this, you can't get it right by chance.

The DSC Lab chart I have is a 5 step B&W wedge. The 8 step charts are quite a bit more expensive.

sebastien,
Unless you know something that I'm not aware of its better not to comapre black ganna to a knee setting. Knees are complicated circuits that have point and slop and effect stauration etc.

Better to just think of the 2 gammas as raising or lowering a point in the curve and dragging everything it near it with them. Gamma is somewhere near 50 IRE and Black gamma is probably around 20 IRE but tests could show you exactly where. I haven't tested the camera so I'm just guessing about the IRE numbers, but these are very common circuits in professional cameras.

http://www.bhphotovideo.com/c/produc...cale_Test.html
11 Step for $115


http://www.markertek.com/SearchProdu...rt&pagesize=20
9 step for $39

and the "dangerous" way
http://www.kozco.com/calibrat/gray.html

And yes the expensive variant
http://www.bhphotovideo.com/c/produc..._CamAlign.html
$1900


although I'd really like to see a continuous ramp. As a former video engineer I understand the importance of accurate test charts but in this case it's just to get a general sense of what the PP controls are doing.