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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 :)

Blue Channel problem

P

Paul Cronin

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I am going to order my Red One next week and have been getting all my ducks($$) in a row with great help picking gear from Peter Majtan and Gibby.

I was forwarded this from a friend who shoots film today who heard about my pending purchase. He said do you know about the Blue Channel problem? I do not know what he is talking about. He said it was compared with the Thomson Viper FilmStream Camera and they said the Red has a problem here. What is this about?

By the way my mind is already made up on the Red One so no problem there. Just trying to stay current with news and always looking for help.
 
There is no specific blue channel problem on the Red One. In prior builds of the r3d codec there was a higher and less 'attractive' noise floor.

All digital sensors are less sensitive in the blue channel than in red or green, and the Mysterium sensor's sweet spot falls at 5000 k, so it is necessary to light a bit more carefully when going with Tungsten.


regards,

JT
 
The blue channel is the noisiest of the three, especially when shooting under tungsten light.
Since the chip is natively balanced at 5000 degrees you can go along way to diminishing this noise by shooting under daylight balanced light. in other words filter the lens or gel your lights.
 
Shoot right and you won't have a problem.

I'm sure if I grabbed a 435 without understanding how to get the best out of it, my results would be horrible, but it certainly wouldn't be Arri's fault!:tongue:
 
Buy 80 filter. I use the 80C to solve the blue channel problem.

80C increases color temperature from 3800-5500 degrees Kelvin and cut around 1 stop.
 
Justin Kirchhoff said:
If you expose the picture correctly you won't have many problems at all with the blue channel.
Click to expand...

But that would mean shooting in daylight all the time :sad: in no lowlight conditions.

It's achilles heel is when it comes to tungsten lighting. That doesn't mean you can't use tungsten lighting you just have to learn how to handle it. I for example over expose (not to a point were I clip highlights) low light scenes and bring it back later in post. I know that the scene will have noise in the shadow that I want to "crush" away with some blacks. So I make sure I'm to stops higher or so in my shadows to bring them to the level I want them to be when I've "crushed" the blacks.

I've learnt to watch for zebras and interpreter the false color system (Im old school film DP).

That's it
 
Boost...

Boost...

If you are shooting by "Practical" tungsten lights and are not replacing the bulbs with "Photofloods" you can use a Colortran (tm) or VariAC to rase the voltage to get 3200K to 3400K or more, even maybe 3800K, that does two things,

1) You can use a less heavy 80 series filter if the lamps are 3200K or more.

2) You get more light so the light loss from the 80 series filter is offset.

In other words if your 80 series filter causes a 2 stop loss and you boost the lights 2 stops you come out even, but do not get blue noise and get a better over all image, you can then add yellow tint later in color correction by adjusting the blue and green gammas to make the color look warmer, and be free of noise.
 
Anyone use the Zebra 2 set in the shadow area ? Never add the time to test it and set it properly. But it could help to set the minimum light you need to have in the shadow (that will be crush in post) before its too noisy.

Always use the false color also...
 
I get great pictures under tungsten without any filter. I can't believe you couldn't find this discussion anywhere, it's been talked about a lot. Just increase your fill a little to compensate so you're not lifting in post. The 80c will just cut light. It doesn't increase blue light. I don't find it that helpful. You'll figure it out when you get the camera. Just test, test, test when you get your camera before you do any jobs. Get used to how to expose for it. It is different than any film/video camera you've ever used.
 
Etienne Caron said:
Anyone use the Zebra 2 set in the shadow area ? Never add the time to test it and set it properly. But it could help to set the minimum light you need to have in the shadow (that will be crush in post) before its too noisy.

Always use the false color also...
Click to expand...

I just use false color. I use histogram and false color in raw mode for highlights, and false color in Redspace for shadow levels. Zebra 2 might be a good idea though. Anyone do Zebras for shadow? I find skin tones can hold until about 15 IRE if I want to actually see them (not silhouette). I'll try setting the Zebra 2 for that range. Maybe 14-20 IRE.
 
SF Geek said:
I just use false color. I use histogram and false color in raw mode for highlights, and false color in Redspace for shadow levels. Zebra 2 might be a good idea though. Anyone do Zebras for shadow? I find skin tones can hold until about 15 IRE if I want to actually see them (not silhouette). I'll try setting the Zebra 2 for that range. Maybe 14-20 IRE.
Click to expand...

I thought Red had said false colour wasn't accurate in RAW mode? Has that changed recently?

http://205.234.135.241/forum/showthread.php?t=21635&page=2
 
No. I don't think it has changed. I do notice a change in readings when i switch to raw mode in false color. The truth of the whole thing is that Raw view mode isn't even raw. It's just a really light gamma curve. If you look at the footage in linear mode in post, you have even more highlight info than you saw in raw mode. I just use these techniques to the best of my knowledge and experience and am sometimes pleasantly surprised to find that I was able to retain detail in the brightest areas. It's kind of like shooting film.
 
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