Color balance of CCD??

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DanHD

Well-known member
I saw over at the red user boards all this commotion about the noise in the blue channel when balancing tungsten, and that the Red has a daylight balanced sensor, and that it's better to use filters and gels then to actually tungsten balance the camera.


Now my question is, does the HPX170/EX1 have a default color balance that creates noise in the red/blue channel?
 
Yes. Most video cameras that I am aware of are daylight balanced. I know my EX1 is MUCH cleaner in 5600K light than 3200K. There is a GREAT resource out there on this. I am digging it up for you.
 
Yes the image typically will be cleaner left on daylight preset using a warming filter, all other things being equal. There will be less noise and less chromatic aberration.

But the warming filter is going to cost you a stop or two - so all other things might not be equal. If you have to bump gain to compensate for the loss of light you avoided shooting yourself in the foot by shooting yourself in the head.

..not sure about that exact cam though
 
So are you saying using a CTB filter on the 5600k preset would reduce noise?

This is just great, I just purchased Tungsten lights. is everything going to be noisy? =(


What causes the additional noise? Is it because the blue CCD has to become more sensitive to account for the increase in red light?
 
What I am saying is that when you preform a "white balance" you are trying to get the camera to equalize it's response to the light it is presented. When there is not enough light for the blue channel (like with most indoor lighting) then the camera must add gain to that channel to make up the difference. So yes, it adds noise to the resultant picture. When you present light with enough blue so that the camera does not have to add gain to the channels, or very little gain, then the picture appears less noisy.

So what you have tungsten light. So does everyone. I suspect if you had the budget to be buying HMI instead you'd have done so. So you need to do what all the rest of us do. Either gel your lights to daylight, or gel windows to match your tungsten lights and use a tungsten to daylight filter on the front of the lens. Film guys do exactly the same thing when they shoot tungsten film (5218) outside. Except it's reversed.

And it's not the increase of red light that's the problem, it's the relative lack of BLUE light that requires the gain.
 
wait Im not sure I follow...so I should try to avoid tungsten light as much as possible?

Even if I'm shooting at night indoors, I should use day lights and daylight balance?
 
DanHD said:
wait Im not sure I follow...so I should try to avoid tungsten light as much as possible?

Even if I'm shooting at night indoors, I should use day lights and daylight balance?
Click to expand...

Yes, if possible. If not, shoot all tungsten, white balance the camera to daylight, and put a tungsten to daylight filter on the camera. if you can't do that, then just white balance the camera to tungsten, and accept a bit more noise.

I've shot indoors at night with nothing but tungsten and it looks lovely. If I didn't know that daylight would look cleaner, I'd never miss it. But I do know. And I like the difference.
 
Well, I've never seen any difference and I've done alot of tungsten shooting. I'll look close at the blues next time I do though. i dont think it's an issue. I don't want to have to balance my rifa88 to daylight, if you know what I mean.

Anyways, wouldnt the same be true of daylight balance? would the reds have more noise?
 
is this really something most dps do? Ive never heard of avoiding tungsten balance before


maybe im just naive
 
perhaps the 170 is less noisy with tungsten than the ex1. ive only heard of the red and ex1 have this problem on the boards
 
BTW thanks Perrone for always coming through for me. You answer the questions I have no one else has the patience to answer
 
pwyll said:
Yes the image typically will be cleaner left on daylight preset using a warming filter, all other things being equal. There will be less noise and less chromatic aberration.

But the warming filter is going to cost you a stop or two - so all other things might not be equal. If you have to bump gain to compensate for the loss of light you avoided shooting yourself in the foot by shooting yourself in the head.

..not sure about that exact cam though
Click to expand...

why would you use a warming filter to bring daylight balance to tungsten?
 
DanHD said:
Anyways, wouldnt the same be true of daylight balance? would the reds have more noise?
Click to expand...

Did you even watch the clip I posted?

Our light has an abundance of red. Far too much in fact. So even under daylight we don't have to add gain to it.

And if you want to see the difference in the footage between daylight balanced light and tungsten, don't look at the blues, look at the shadows.
 
DanHD said:
perhaps the 170 is less noisy with tungsten than the ex1. ive only heard of the red and ex1 have this problem on the boards
Click to expand...

The 170 has 960x540 imagers. Though they are still daylight balanced most likely. But it's easier for those imagers to gather light since they are not as dense. Actually, that may not be true since they are 1/3".
 
DanHD said:
and wouldnt you use a daylight to tungsten filter, not the other way around?
Click to expand...

Just pretend like your camera has film in it. You have daylight film loaded, and you are shooting tungsten light. You can either use blue gel on the lights (CTB) or you can use a filter on the lens. If you have a load of tungsten lights on a scene, gelling them all separately is a royal pain. It's easier to simply use a filter. And if you have a window in the scene, to use a CTO gel and bring it's color in line with the tungsten fixtures.

Get it?

80 Series Color Conversion Chart


• 80A increases color temperature from 3200-5500 degrees Kelvin (commonly used with 3200K lamps)
• 80B increases color temperature from 3400-5500 degrees Kelvin (commonly used with photoflood lamps)
• 80C increases color temperature from 3800-5500 degrees Kelvin (commonly used with flashbulbs)
• 80D increases color temperature from 4100-5500 degrees Kelvin (commonly used to remove extreme orange or red)
 
DanHD said:
BTW thanks Perrone for always coming through for me. You answer the questions I have no one else has the patience to answer
Click to expand...

I think as time goes on, those people who've never shot film will ask a lot of questions like these.

Just like people won't appreciate how differently Fuji and Kodak film stocks render light. I'm a fuji guy in a kodak world unfortunately.
 
Perrone - thank you for these posts. I knew there were issues with gain in the blue channel, but never knew why.

P.S. - your next post is your 1000th - got any big plans?
 
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