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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

DPs please check me on this...

Jay A. Kelley

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Daren, Greg, David, RED Team, etc.

Check me on this and see if I have it:

I have been trying to wrap my head around RED's sensor. I have been spending a lot of time trying to learn the best way to feed it, and what it likes best. Here's the bottom line:

RED's sensor provides the best s/n ratio in the RED channel (Ironic) and the WORST s/n in the blue channel.

So that said, shooting daylight balance light sources will feed the sensor a lot of blue light which it is hungry for, and balance against the sensors weak points.

Shooting tungstun however, means you will feed the sensor a lot of red light, and it will starve for blue. When you go to post, any type of low light situation will result in blue noise before anything else, since you did not balance things out well when you were shooting.

I shot some green screen a while ago and had the good fortune to the same actors, in the same outfits using both tungstun, and KINO daylight each time. This is what brought it home for me.

I look at the RAW video output from the camera, no WB, no curves, nothing. The tungstun set was pretty orange, while the daylight set was far more balanced. Furthermore, color work in post was 1000x easier with the daylight set as blues and skintones were more balanced.

Ok, nothing new here I know.

But, when shooting outside, is there TOO MUCH blue light? I have hear tell people are using an 85A filter. This filter cut's down on the amout of blue light getting to the sensor correct? So are we saying that outside we've gone too far in the other direction?

Shooting Tunsten, we're in a position where the blue is much lower and so to counter that you can use a daylight source, or gel your tungstun to get more blue into the picture. I read somewhere that in regards to the blue channel, the RED falls below 320ASA by a bit.

Is a possible solution inside to use a filter that cuts down the amount of RED light and to try to balance it that way? I know we'll lose our 320ASA but my focus right now is more one of color balance.

Personally, I am not wild about using a color filter indoors, I would PREFER to just work the light sources. But what about shooting on a city street, were I do not have that control. And there are a lot of tungstun porch lamps around.. Is a filter good then?

I dunno, I can't seem to get comfortable using any kind of color correction filter in a low light situation. Outside, if the 85A balances things a bit, I can get behind that one, but inside, hmmmm.

One thing I can see, if using an 85A IS a good idea, then all you people with two stage matteboxes better get an upgrade (Like me.. Ouch).

Outside:
85A
Pola
Basic ND
ND Grad

Crap, I'm one tray short.

Of course now with all those filters, then we come back to this IR issue everyone's talking about..

But that's another thread..

I'm just saying

Jay
 
Jay,

Here's my 2 cents...I don't have my cameras yet (**#@) so I can't test, but all broadcast video cameras do have multiple filters to help the camera "balance" across 3000K-6000K, many Broadcast camera even have an "electronic" 5600K switch.

My point is: It's common to use filters to compensate for color balance and light level,(ND filters) in front of the chip block.


Dave
 
Jay,

An 80A filter is what you would need, and yes, you are right about needing a warming filter when shooting on overcast days. I would also recommend looking at getting some very low density color correction filters as well (cyan, magenta, yellow), just in case the regular filters aren't creating a perfect balance.

I've been beating the optical filtering drum here for a while, and elsewhere... A good image doesn't always come cheaply, especially with interior shooting.

Hope that helps!

Chris
 
My biggest concern with being forced to balance to daylight for interior/nighttime is that bluer light is less flattering on some talent. And, a battery of HMI's costs a hell of a lot more and is less reliable than a set of quartz instruments.

I just shot some cloudy exteriors without optical warming and will watch for noise.

Michael
 
Wish Mysterium was 3200K balanced, instead of 5500K. Wouldn't really look forward to throwing an 80A on, and losing 2 stops.

Guess I'll have to test, when I get mine.
 
Wish Mysterium was 3200K balanced, instead of 5500K. Wouldn't really look forward to throwing an 80A on, and losing 2 stops.

You know, I've been thinking about how sensitive a tungsten balanced sensor would be, and I think you would still be in the same boat to a certain degree because you can only be as sensitive as the lowest sensitivity channel in an optically balanced system like this (assuming you ND separate channels photosites). So while I think you might see an improvement, my gut feeling is that you would still loose sensitivity.
 
What do you mean? The image won't look blue when photographed.

Given that most skin has red hues, bluer light brings out blemishes and imperfections more. (Makeup fixes much of this, of course.)

Michael
 
true if you only look at the blue channel under tungsten you will see noise AND we look at images 24fps/29.97 and we look at all 3 channels ...
you get a good ISO 320 exposure under tungsten or daylight and you'll have a good image to work with ....

so the question is - you found noise in the blue channel - how did it key ?

green screen - in a quick test i found kino flo green tubes not acceptable - i'll avoid them till i can do a test with firmware 16 .... from quick test -best was daylight on green screen and talent ...
i find that even with the blue noise ( tungsten light) the keying is excellent
 
i find that even with the blue noise ( tungsten light) the keying is excellent

That's reassuing. In greenscreen situations it's usually pretty easy to go all daylight balanced.

But the whole issue does beg the question - why not have a tungsten balanced sensor?

You rarely need to cut light inside so you don't want to filter that. Outside you're trying to kill light to start with, so tossing a color balance filter on would be fine.

Was that something that was tested and daylight chosen because superior results were obtained?
 
blue reciprocity failure

blue reciprocity failure

I'm starting to think of this as a-sort-of digital singlechannel reciprocity failure. I like Card Maverics ideas. Very similar to underwater issues...only completely reversed. Filter use will force you to 'open up' more in certain situations and shoulder-in the blue channel up the histogram. Of course you lose light overall either at the lens with an 80a or at the fixture with CTB gels. The choice is yours. Many underawater guys (correct me if i'm wrong) prefer to fix it in post. You simply can't drag a gen. set and hydroPars everywhere you go. Bottom line, if you have the stop...correct colour and open up. At least until your lenses get soft and make a decision...wide open diffraction softness or noisy image.

Your call.

Of course build 16 hasn't been released.
 
filters that "fix" the problem

filters that "fix" the problem

I haven't shot with the red yet (seriously can't wait) but having used pretty much everything else out there I can sympathize. It seems you are discovering that thing that plagues all sensors and film stocks: You have to pick one lighting condition to favor in the design. C'est la vie! Or as we say in the south, crap.

The filters*** I would test in your instance come to mind from a quick review of the ASC manual (I have an older 7th ed - so I can't tell you which page numbers - check your index) regarding MIRED shift leans me towards a Color compensating filter in the 80A range. A thin 80A 4 X 5.6 with a 2 stop loss would suck if you weren't using a RED. However, you do have all that low end signal that you can use in post! If you want it to be perfect, I have this great gaffer - he makes his own balloon lights ... the real answer (unfortunately) is more light + CC filters on camera - same as with K5218.

*** Has anybody talked to the filter vendors that are going to be at NAB this year? It might be a good idea to contact them ahead of time and see if you can do some tests with suggested filters to compensate for this issue. Maybe they could develop a RED filter pack. Maybe they could do a bulk buy (they like that sort of thing - and so do we). Maybe it will make them look like they care about what their customers want. Maybe ::)

"Oh sweet happy day
When Jim sends my RED FedEx
Camera Goodness"
RED Haiku
 
Would a waveform/SDI monitor have helped you set up shot properly or do many non-studio types go to this extra effort? I was just introduced to the benefits of using such a monitor this last week-end, though it does take time to come up with your calibratons. But once done, great images
 
What do you mean? The image won't look blue when photographed.

Hi,

Personally I much prefer the look of tungsten light over HMI's or Kinoflows of any color balance

Has anybody tried a magenta filter with a Red one? it helps balance a Viper.

Stephen
 
I've shot enough overcast exteriors with the Red and didn't notice an increase in noise. I still haven't tried an 80 filter for tungsten yet. Maybe 16 will make the point moot.

I find that daylight is more flattering for white skin tones. Under a digital chip with tungsten I find that often they look too red. Other skin tones work great in most situations.

There is a posting about a tungsten balanced sensor and it was explained that the nature of digital sensors makes them daylight balanced, not the choice of the camera or chip manufacturer.
 
In my testing of shooting with the red under tungsten I found that if you use an 80D (2/3rds of a stop loss) instead of an 80A (2 stops) you get most of the noise improvement. I think that an 80A is an over correction because the sensors native balance is 5000K (I think) not daylight film stocks 5500K.



www.belladonnathemovie.com
 
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