question to graeme or deanan? TED said:rate red 250 in low con and 400+ in high con

[Cüneyt Kaya]

here is the quote:

I’m explaining to people on a pretty regular basis that the RED is kind of like 2 cameras in one – one camera for low contrast, low DR photography where you can rate from 250 ASA on down as long as you don’t overexpose, and use the Raw View mode in the camera to check the levels, and have really nice imagery – learning to use the histogram on the right side (the right 3rd of the of the histogram scale) for low con imagery can be your best friend...

... and one camera for high contrast, high DR challenging photography where you have a huge range from under to over, and you can expose at 400 ASA or higher, and as long as you don’t clip the highlights, you will be amazed at how much range you have in the mids and shadows to work with... This camera is way more sensitive that people give it credit for under the proper high contrast shooting conditions... Using the histogram from 2/3’s full on down for high DR photography can be your best friend.

The biggest mistake I see people make is letting things blow out because they are worried about the shadows, those shadows can hold clean and gorgeous like crazy – I see it all the time on properly exposed high DR imagery.

If you use REDspace for your overall exposure setting, and use RAW View for checking highlights as you work and check exposures you will have effectively done what MacGregor describes in his Rec709 at 640ASA testing. REDspace for all types of photography can be your best friend, when used in tandem with checking highlight exposure in RAW.

The RED ONE has various “sweet spots” for exposure depending on the various contrast conditions, color temperature of light being used and a number of other creative factors – that’s one of the reasons it’s such a nice tool to work with. The more testing and experimentation a DP has time to do, the more they learn about how far the can push and pull the images to create the look and feel they want – the joy of RAW cinematography.

+ Ted

here is the thread
http://reduser.net/forum/showthread.php?t=28705&page=5

and mac says
"View RAW seems to be just like if you set the camera to 250ISO, camera RGB, 5000ºK and any other value set to default. That´s why if you use false colour with this view (which you shouldn´t use btw) will give you a real world ISO of something like 100.

http://reduser.net/forum/showthread.php?t=28705&page=12
__________________
so why?

an explanation is needed here.
How does a digital sensor work related to a ASA rating and Contrast of a scene?
And after the explanation, how to use a lighmeter correctly with red knowing this explanation...
and how to rate if you are only shooting RAW VIEW so the oldschool DOP`s lighmeter match.

[Deanan]

It's all about where you place mid grey and how much highlight versus shadow range you want.

[gbalaji]

It's all about where you place mid grey and how much highlight versus shadow range you want.

Deanan,

I was told in this user forum that the false color and raw mode is not the exact replication of the exposures. Is it true and if yes what's the best method to expose Red One with false color.

Currently exposing with histogram!

[Graeme Nattress]

Basically, the higher the ISO, the more highlight protection you get. Each stop you increase the ISO, you gain a stop highlight protection. When there's low contrast you want to expose to the right, ETTR, which necessitates thinking of the camera as a lower ISO.

I'd not ETTR by adjusting ISO though, but use the raw clip meter or histogram in RAW to achieve it precisely.

Graeme

[michael zaletel]

Can someone explain this in greater detail with a few histogram pics and stills? I can tell this topic is extremely important and want to make sure I understand. The more everyone understands this, the better will be Red's quality perception in the marketplace. I have heard that even some famous DP's still aren't exposing Red footage properly and perhaps that is due to a lack of practical application examples of this topic. If I'm the only one that still isn't 100% sure what all of this means and how to properly expose Red footage in different lighting situations, then please at least explain it to me. ;)

In particular, are filters essential to protecting highlights and shadows and acheiving a rich center-weighted histogram. Is a center-weighted, spread-out between 5 and 95 optimal for all shooting situations? Probably not. So how should the histogram look in a few common scenarios? Also, how do you switch the exposure meter and histogram showing on the EVF between RAW and say RedSpace or REC709? Is that possible? What menu? Finally, how can you tell if you have adequately exposed color for optimal grading and finishing in addition to optimal light exposure?

Please, please advise. I know this is perhaps the most important thing for me to learn right now, other than improving content quality of course. ;)

"I'd rather over expose a great scene than perfectly expose a mediocre one."

-michael zaletel
(shooter)

[ericyoung]

Ditto Michael's post! :)

[Uli Plank]

Have a look at this for a start:

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

The RED One is very much like a DSLR shooting RAW, only difference: up to 120 fps;-)

[Alexander Christ]

...another good read: http://www.adobe.com/digitalimag/pdfs/linear_gamma.pdf

[David Mullen ASC]

You're not changing your contrast or dynamic range with different ISO ratings, you are merely protecting more highlight detail with higher ratings, at the expense of the shadow detail (and noise.) It makes sense to some degree to use higher ISO ratings in bright daylight in that hot highlights tend to be more common than really dark shadows. Though you get into the problem of needing heavy ND in order to avoid being stopped down too much.

[michael zaletel]

Thanks for the link Nomad. Within that article was a link to another valuable article based upon a very long discussion the author had with Thomas Knoll (author of Photoshop and Camera RAW) regarding exposure on linear devices.

Expose to the right.
http://www.luminous-landscape.com/tutorials/expose-right.shtml

Excerpt:

"A 12 bit image is capable of recording 4,096 (2^12) discrete tonal values. One would think that therefore each F/Stop of the 5 stop range would be able to record some 850 (4096 / 5) of these steps. But, alas, this is not the case. The way that it really works is that the first (brightest) stop's worth of data contains 2048 of these steps — fully half of those available.

Why? Because CCD and CMOS chips are linear devices. And, of course, each F/Stop records half of the light of the previous one, and therefore half the remaining data space available. This little table tells the tale.

This realization carries with it a number of important lessons, the most important of them being that if you do not use the right-hand fifth of the histogram for recording some of your image you are in fact wasting fully half of the available encoding levels of your camera.

The simple lesson to be learned from this is to bias your exposures so that the histogram is snugged up to the right, but not to the point that the highlights are blown. This can usually be seen by the flashing alert on most camera review screens. Just back off so that the flashing stops."


Does all of this apply to the RED ONE sensor or are there differences to be considered?

Please advise, Graeme?

-michael zaletel
(shooter)

[Graeme Nattress]

Exposing to the right is generally good advice for the RED One.

Graeme

[Uli Plank]

The REDs sensor is linear as well, and the RAW data too.

But don't "overprotect" your highlights. Small light sources or reflections shouldn't be a reason to underexpose all the rest, since large areas of our scene might drop into noise. That's why the "traffic-lights" only come up if more than 1% of the image area are affected.

But use your own judgement, content is king!

[michael zaletel]

This excerpt was helpful as well. Thanks again Nomad. :)

The following explanation by Bruce Lindbloom may help you understand what's going on with the above technique...

"For film based photography, the highlight end of the scale is compressed by the shoulder portion of the D/log E curve. So as brighter and brighter objects are photographed, the highlight detail gets gradually compressed more and more until eventually the film saturates. But up until that point, the highlight compression progresses in a gradual fashion.

Solid state sensors in digital cameras behave very differently. As light falls on a sensor, a charge either accumulates or dissipates (depending on the sensor technology). Its response is well behaved right up until the point of saturation, at which time it abruptly stops. There is no forgiveness by gradually backing off, as was the case with film.

Because of this difference, setting up the exposure using an 18% gray card (as is typically done with film) does not work so well with a digital camera. You will get better results if you set your exposure such that the whitest white in the scene comes close to, but not quite reaching, the full digital scale (255 for 8-bit capture, 65535 for 16-bit capture). Base the exposure on the highlight for a digital camera, and a mid-tone (e.g. 18% gray card) for a film camera."

Now if I can just apply the same "proper exposure" principles to my scripts, sets, sfx and scoring. :)

-michael zaletel
(shooter)

[Sanjin Jukic]

More good readings about our favorite topic:

David Battistella : Exposing the RED: Perfect Exposure, Every Time>>>(must search at Google>>> (http://www.google.com/search?client=safari&rls=en-us&q=David+Battistella+:+Exposing+the+RED:+Perfect+Ex posure,+Every+Time&ie=UTF-8&oe=UTF-8))

Basic rules of exposure>> (http://www.reduser.net/forum/showthread.php?t=24088)>

- REDspace and RAW>>>Stuart English>>RED Workflow Wizard>>> (http://www.reduser.net/forum/showpost.php?p=281508&postcount=5)

- Exposing>>>Stuart English>>RED Workflow Wizard>>> (http://www.reduser.net/forum/showpost.php?p=301182&postcount=14)

- Colour space>>>Graeme Nattress>>>RED Problem Solver (http://www.reduser.net/forum/showpost.php?p=400880&postcount=3)

- The skill of exposure>>>Graeme Nattress>>>RED Problem Solver>>> (http://www.reduser.net/forum/showpost.php?p=351590&postcount=49)

- Exposing for the RAW format>>>Rob Lohman>>>Red Team>>> (http://www.reduser.net/forum/showpost.php?p=112468&postcount=20)

ISO is metadata>>>Graeme Nattress>>> (http://www.reduser.net/forum/showpost.php?p=227676&postcount=16)

Exposure differences between RAW - RED SPACE>>> (http://www.reduser.net/forum/showthread.php?t=18670)

Setting the right ISO is important>>Graeme Nattress>>> (http://www.reduser.net/forum/showpost.php?p=227441&postcount=10)

Digital Cinema Dynamic Range>>Stu Maschwitz (http://prolost.com/blog/2008/2/22/digital-cinema-dynamic-range.html)

Determining ISO>>>Evin Grant>>> (http://www.reduser.net/forum/showpost.php?p=148399&postcount=31)

Raw and saturation question>>David Mullen ASC>>> (http://www.reduser.net/forum/showpost.php?p=112499&postcount=22)

RED colour space workflow>>Graeme Nattress>> (http://www.reduser.net/forum/showpost.php?p=119160&postcount=4)

Clipping highlights 1>>Graeme Nattress>> (http://www.reduser.net/forum/showpost.php?p=119575&postcount=9)

Clipping highlights 2>>Graeme Nattress>> (http://www.reduser.net/forum/showpost.php?p=119579&postcount=10)

Exposing RED 1>>David Mullen ASC>> (http://www.reduser.net/forum/showpost.php?p=131966&postcount=4)

Exposing RED 2>>Ian Bloom>>> (http://www.reduser.net/forum/showpost.php?p=132002&postcount=7)

Exposing RED 3>>Mark Crabtree>>> (http://www.reduser.net/forum/showpost.php?p=132022&postcount=9)

Grain/noise not problem but aspect of low light shooting>>D. Gregor Hagey csc>> (http://www.reduser.net/forum/showpost.php?p=116314&postcount=59)

[michael zaletel]

sweetness!

"with all your getting, get understanding" - Proverbs 4:7

-michael zaletel
(shooter)

[Martin Weiss]

Sanjin, awesomly helpful list, thanks!

The first link seems to be wrong, even after removing the double http://.


/CollegeEssays/IHateCows.html.net/articles/battistella_david/RED_camera_Exposure.php

[Daniel Browning]

A 12 bit image is capable of recording 4,096 (2^12) discrete tonal values. One would think that therefore each F/Stop of the 5 stop range would be able to record some 850 (4096 / 5) of these steps. But, alas, this is not the case. The way that it really works is that the first (brightest) stop's worth of data contains 2048 of these steps — fully half of those available.

Why? Because CCD and CMOS chips are linear devices. And, of course, each F/Stop records half of the light of the previous one, and therefore half the remaining data space available. This little table tells the tale.

This realization carries with it a number of important lessons, the most important of them being that if you do not use the right-hand fifth of the histogram for recording some of your image you are in fact wasting fully half of the available encoding levels of your camera.

The simple lesson to be learned from this is to bias your exposures so that the histogram is snugged up to the right, but not to the point that the highlights are blown.


There is lots of good information from the Luminous Landscape, but this particular bit of information is incorrect.

ETTR improves the image because it results in more light (more photons); the number of steps/levels has no effect. This is all explained in great detail here:

The Consequences of Noise (http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html)

[Mark Pugh]

Exposing to the right is generally good advice for the RED One.

Graeme

Ted and Graeme are totally right. "change the ISO ratng depending on the contrast of the scene" and "expose to the right" are basically two ways of saying the same thing: "Give the sensor as much light as you can without clipping"

The first exterior shot I ever took was across a very foggy lake. Very small range of stops in the scene. I exposed once at 400iso, and once at 100iso. Results were remarkably different noise-whise.
Looking at the shots in post, the 400iso shot looked like what you'd expect if you shot really fast but grainy film.(early build).
The 100ISO shot looked like creamy 50iso film.
As the were no nasty highlights in the scene to worry about, darkening down the monitor by changing tge ISO,but keeping an eye on clipping in the histogram yeilded fantastic results. I learned a lot from that about maximizing results from the red one.

[Graeme Nattress]

Yes, different ways of saying and looking at exactly the same exposure philosophy.

Graeme

[David Mullen ASC]

Ted and Graeme are totally right. "change the ISO ratng depending on the contrast of the scene" and "expose to the right" are basically two ways of saying the same thing: "Give the sensor as much light as you can without clipping"


That doesn't sound right to me -- I'd like someone to explain why higher contrast scenes benefit from higher ASA ratings, because it seems to me that the dynamic range of the sensor is a constant and all you are doing is deciding whether to capture more highlight or more shadow information by playing around with the ASA rating. But you can't extend the dynamic range being captured with higher ASA ratings.

So what does low contrast versus high contrast have to do with ASA ratings? Are you basically saying that with a low contrast situation, you have more freedom to push the image "to the right" exposure-wise because you don't have hot highlights to worry about? But that really doesn't mean you are extending dynamic range in high contrast situation by using a higher ASA rating and thus exposing more "to the left" to protect the hot spots.

[Cüneyt Kaya]

That doesn't sound right to me -- I'd like someone to explain why higher contrast scenes benefit from higher ASA ratings, because it seems to me that the dynamic range of the sensor is a constant and all you are doing is deciding whether to capture more highlight or more shadow information by playing around with the ASA rating. But you can't extend the dynamic range being captured with higher ASA ratings.

So what does low contrast versus high contrast have to do with ASA ratings? Are you basically saying that with a low contrast situation, you have more freedom to push the image "to the right" exposure-wise because you don't have hot highlights to worry about? But that really doesn't mean you are extending dynamic range in high contrast situation by using a higher ASA rating and thus exposing more "to the left" to protect the hot spots.

thank you david.
you did say what i wanted to say.

[Etienne Caron]

Sanjin,

Put "Conversaciones en Rojo" from Alfronso Parra in your list:

http://www2.alfonsoparra.com/php/ver/structure_all.php?ln=spa&n=3&s=3&id_cms=489&id=374

Great stuff...

[Blair S. Paulsen]

I'd wager the perceived DR, not the actual DR, is improved in high contrast material by staying out of the clip. It is my theory that this impression is created mostly by what is revealed in the image by the second step in the process - the grading stage. Remember - with the RedOne we don't paint in camera, we tweak the RAW data set in RA, RC, Scratch, etc.

In low contrast scenes, where a hard clip is much less of a concern and more content of interest is in the bottom (left) half of the histogram, you want to expose to the right. This is even more critical due to the sampling math inherent in a linear device. Resetting the working ISO is simply a means to an end, it makes the exposure tools on the camera read lower so you open up the iris.

The native properties of the sensor do not change - it is what it is, therefore:

My own working style is to leave the ISO at 320 at all times. When shooting day exteriors or other high contrast scenes I take the clip indicators (stoplight primarily) more seriously and when in doubt I close down another half stop. When shooting under well controlled lighting and soft sources I make sure at least one of the stoplights is lit, usually all three.

Despite the many warnings about false color I use it all the time as a reference point. I want to see where 18% grey falls, I want to see what portions of the scene are reading down in the blues, I want to see if wardrobe or surfaces I care about are yellow, orange or red.

I do toggle to view RAW to check the clip point. I work in view RAW exclusively when there are no clients/producers camped in video village. In a perfect world I would assign different view options to various monitor feeds around set. This can be done with LUT boxes on bigger shows but it would be easier if it could be done by camera menu - I'm pretty sure the RedTeam all over this for Epic, they're sharp cookies.

In any case, I find that by leaving the ISO alone I don't have to make a second mental adjustment, YMMV.

Bottom line - I am a place and fall Cinematographer - which means I am focused on getting specific elements of the scene placed in the zones (Ansel Adams index) I want them in. BTW - I carry an Digi-Con when I need more working DR in high contrast settings where greater light control is impractical (where's that 80 by silk and 17 grips) and restore contrast in CC.

Cheers - Blair #19

[Chris Kenny]

So what does low contrast versus high contrast have to do with ASA ratings? Are you basically saying that with a low contrast situation, you have more freedom to push the image "to the right" exposure-wise because you don't have hot highlights to worry about? But that really doesn't mean you are extending dynamic range in high contrast situation by using a higher ASA rating and thus exposing more "to the left" to protect the hot spots.

Sure. You're just shifting things over, and protecting highlights at the cost of introducing shadow noise. The key is, though, that shadow noise is more acceptable in high-contrast shots. Not because of anything technical happening in the camera, but simply because of human visual perception. In a shot with very bright areas, especially one dominated by very bright areas, you can't see shadow detail as well because of glare.

Thus, in a high-contrast shot, you can expose to the left more to protect highlights, without worrying about overly noisy shadows.

[Mark Pugh]

Are you basically saying that with a low contrast situation, you have more freedom to push the image "to the right" exposure-wise because you don't have hot highlights to worry about?


Exactly. It means in Red Alert, you can bring the image back down, and the image will be less noisy than if you'd shot higher ISO.
Try it for yourself!
I'm telling you, on that foggy lake, the difference in results between setting the camera at 400ISO and at 100ISO were chalk and cheese. On my little 5.6" monitor, the two versions looked the same. Viewed on a decent size screen, it was another story.
The more light you can give the sensor, without clipping being an issue, the creamier will be your results, especially if you're shooting 3K or 2K.
I guess it's mostly because your pushing the sensor noise in RedAlert or whatever, down into the shadows, but also possibly partly due to what Redcode is doing (being less "lossy" to the mids and highlights than the shadows). I could stand corrected on that part.

[David Mullen ASC]

But everyone is assuming that in a high contrast situation, you're going to want to bias the exposure to protect the highlights. But I can imagine a high-contrast scene where all the important detail was in the shadows and the areas of overexposure were limited to small areas that did not have important scene information. Imagine a room full of black bowling balls piled high with small areas hit by bright spotlights but the bulk of the room was rather dim and underexposed. You'd set the exposure so that the main area of visual interest was going to reproduce with good detail and low noise -- which in this case may be the dark bowling balls sitting in the dim shadows.

[Chris Kenny]

David, yes. I think the "high-contrast shot" most people are probably picturing in their heads in this thread is more of a daylight exterior sort of situation.

[Martin Weiss]

David Battistella : Exposing the RED: Perfect Exposure, Every Time
Ok, after a night of sleep, I figured out the correct url. Follow this link (http://tinyurl.com/redred77)

[Uli Plank]

Absolutely, David, your second paragraph puts it right.

Noise is not setting in suddenly, like saturation, but the ratio of signal vs. noise is gradually getting worse the more you expose to the left. So, a low contrast scene profits from staying away from those areas while still avoiding saturation.

Changing ISO just helps you judge it on the screen, but looking at a histogram in RAW mode and exposing to the right is always correct – as long as you have a grading session on your schedule.

The only exception to this rule: you want to deliver useable footage right from your camera. i. e. use the RED like a video camera. Then I'd switch to Rec709 and expose visually while adapting ISO to the scene.

[Frank Mirbach]

I did some exterior daylight tests lately and had the impression that there is not such a big difference in the histograms between RAW and 709. It seemed to me the 709 offered a more realistic image that RedSpace, where the colors were highly exaggerated and highlights clipped too early. So exposing to the right in 709, even a bit "over the right" produced a good exposure in RAW. Can anyone confirm this ?

Frank

[JanneJansson]

If you take a step back and think how the exposure process is then maybe it is time for some new ideas. The aperture of the lens is supposed to control and regulate the light in to the camera. But usually the light is adjusted before it get there with filters. The aperture is used as a creative tool to give the scene the proper feel with depth of field. If the lens had a active filter (like a transparent LCD that can go from clear to black) light regulation built in the camera or the lens. Then you get new levels of control without carry many cases with filters. ..or if you think more about the "digital filter" thing, you could probably build stuff with same tech that is in normal flat-TV that have multi properties like a grad filter, dynamic limiting of high light leves areas etc..

[Graeme Nattress]

Exposure "rules" are only for a mythical "general" scene exposed at the mythical "correct" level. As David points out, it's the art and skill of the cinematographer to either use the "rules" or not to achieve an exposure that meets the needs of the shot in terms of the story it has to tell.

It's relatively ok to give technical advice, but your common sense and aesthetic have to take over when it actually comes to setting that f-stop on a real lens pointing at a real scene.

Graeme

[David Mullen ASC]

I did some exterior daylight tests lately and had the impression that there is not such a big difference in the histograms between RAW and 709. It seemed to me the 709 offered a more realistic image that RedSpace, where the colors were highly exaggerated and highlights clipped too early. So exposing to the right in 709, even a bit "over the right" produced a good exposure in RAW. Can anyone confirm this ?

Frank

Well, I believe RAW is (of course) the widest exposure range being captured, so Rec 709 gamma will be a bit truncated in terms of what gets displayed.

Actually that's more or less how I like to work, which is have a display -- whether thru a LUT or some other method -- which is higher in contrast than what is being recorded, so I know I'm giving myself some extra detail to work with in post if I can make it look right for the more limited dynamic range that the display is showing. Then in emergencies when the contrast is over the top, I can check the RAW image to see what I will actually get to work with in post.

The trouble with monitoring in RAW is that you have to train yourself to remember that some visible shadow detail is buried at the noise level and will probably be less visible once you make the blacks nice and rich in post. Plus you might not give yourself any leeway on the highlights in post if you lit the scene so that you need every bit of overexposure detail visible in RAW.

On the other hand, I think, in order to get a film look, you're going to end up compressing (with a knee control or something) every bit of over-exposure detail to be visible in the final display gamma of the project, so one LUT I've sometimes used (for the Genesis) is where I crush the shadows down a little to force myself to add more light there and get detail recorded above the noise floor, but used all of the highlight information in RAW. But then, I have no wiggle room in post because now I've incorporated every bit of overexposure detail into the planned image.

I monitored my RED projects using Rec 709 and generally that worked out in terms of how I like to expose. I only wish I had crushed the blacks on the set monitor a bit more to force myself to add more fill. Trouble with a lot of LCD monitors being used on sets is the black level and backlight when viewed off-axis often lifts the image and shadows, giving you a false impression that you aren't adding enough contrast to the lighting.

[Joe G.]

"I only wish I had crushed the blacks on the set monitor a bit more to force myself to add more fill. Trouble with a lot of LCD monitors being used on sets is the black level and backlight when viewed off-axis often lifts the image and shadows, giving you a false impression that you aren't adding enough contrast to the lighting."

Thanks David. Is this true for all digital cameras? Do they all need a little more fill than you would intuitively expect? And can contrast be increased in post with no loss in image quality?

[David Mullen ASC]

Within limits -- and it's not particularly a digital camera issue, if you want to slightly crush the blacks in a D.I. with something shot on film, it helps to have a little extra fill to compensate. I'm not talking about using flat lighting either because you can't really fix that in post, it looks too artificial.

There is a classic connection between deep blacks and shadow detail in that the richer the blacks in the print or in a digital color-correction, the more low-end detail is buried. This isn't necessarily a bad thing either, it's why many cinematographers used to overexpose negative film when doing a photochemical post and contact print -- you end up with deeper blacks once you print down and detail seems to fall-off nicely into pure blacks rather than into mud.

With film, the low-end detail tends to be grainy and in digital, it tends to be noisy, so the problem is similar -- you want the flexibility to bring down the blacks yet retain some shadow detail, so you want to use fill light carefully and thoughtfully with this in mind while avoiding the look of obviously filled-in shots or flattened lighting without good contrast.

But it's partly a taste thing -- I like really deep blacks. I like ENR prints for example, or prints using Vision Premier stock. Solid blacks in a frame add depth and dimensionality to the image.

I once talked to Roger Deakins about use of fill light and he said that he really didn't think of lighting in those terms.

If you watch his movies, he likes things to roll-off into black -- what he does to reduce the need for fill is to wrap his key around, sometimes by putting a soft light that is on the same side as the key light, just adding to it more frontally but less intense -- so you have the effect of a side-lit face but both eyes are lit because the key feathers off as it becomes 3/4 frontal, yet there is no light on the shadow side, so 1/4 of the face stays nice and black. Of course, other times he will have scenes filled in more naturally just from the nature of the room lighting and the ambience. But you rarely see what could be perceived as a fill light, just there to fill in the shadows. Instead you see varying degrees of softness from the key light. It's a good way to think about lighting.

I'm a bit more technical about it, I tend to always have some fill from behind camera, but knocked so far down as that it barely registers. It is sort of my safety net because if I see in the first take that the actors are doing something where they end up facing away from their key, I have the option of slightly brightening the fill to compensate. But sometimes the electricians look at me funny because I set up this fill but knock so far down as to make you wonder if it is doing anything. I find that at the least, it tends to create a nice glint in the eyes and clean up some noise and color cast in the shadows.

But there are other times where I just put some white cards or cloth down off-camera to increase the ambient fill in the room. And if you are shooting in a white-walled space, sometimes there is plenty of fill without adding anything - in fact, you sometimes need to add negative fill to get some contrast back.

[hans de vries]

incredible, all this. I used to be fine until I started reading all the threads sanjin mentioned. I've decided to go back to simplicity again. rgb parade in rec 709, and if I appear to have been slightly off, exposure adjustment in redcine. Work needs to be done!

[Joe G.]

David: "I tend to always have some fill from behind camera, but knocked so far down as that it barely registers. It is sort of my safety net because if I see in the first take that the actors are doing something where they end up facing away from their key, I have the option of slightly brightening the fill to compensate."

That's why you get the big bucks! Great advice.

[Joe G.]

Graeme?
"I'd not ETTR by adjusting ISO though, but use the raw clip meter or histogram in RAW to achieve it precisely."

A question about exposing with histogram and stop lights.

Do the "stop lights" go off as soon as any one pixel in that color peaks at 100?

I have a problem using histograms, for the following reason: The place you want to see the most critical info (at the right) has the smallest peaking. It's so small, it's hard to see if it's there or not. Is there a way to highlight what has peaked so that it is more obvious?

Like -- could this turn into a FEATURE REQUEST to ZOOM IN to the right most part of the histogram, so that it is easier to see exactly what's there in the most critical area? You could call it the ETTR ZOOM MODE or something.

[Graeme Nattress]

I think Stuart knows the numbers, but a certain small percent of the pixels have to clip before the light activates. A single pixel clipping will not turn the light on.

I tend to get very good results using the raw vertical bar graph indicator myself.

Graeme

[Martin Weiss]

Isn't it 1% ?

[Evin Grant]

2% per channel I believe.

David I really like the Deakins approach of falling off from the key side. I tent to always have a light panel or small unit either on camera or right next to camera so I can add just the slightest taste of fill or glint in the eye.

Example...
http://www.evingrant.com/pics/DG1.jpg