color correctd lamps

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diego80

Active member
as a I have a little budget,

I was planning of starting collecting a DIY small set of lights and hardware, instead of invest my money

on cameras.

the first light I thought of was a Flourescent Light.

I read today something that I didn't know, which I would like to quote.

for simplicity I took a pic of the whole page:

http://dl.dropbox.com/u/377563/mie2.jpg

it is extracted from Blain Brown's second edition of "motion picture and video lighting" by focal press

it is about the color correction of lamps, which I did not knew abuot.

I have found the same info on the coollights site:

http://www.coollights.biz/cl655pmd-cool-lights-portable-dimming-watt-softlight-p-71.html

now I am asking:

what would be the problem if lamps are not color-corrected?

thanks very much
 
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the problem is not in the color of the lamp, it is in the color of other lights.
since it is video, you could shoot with any light and correct in post.
but it is probable that your scene will include some light source you can not decide and you need to match them with your own light.

The biggest problem with led or fluo lamps, is they are on the blueish side.
So if you shoot in a room that has regular bulbs, then your light will drop a blue cast and the rest will turn to redish. Pretty impossible to correct in post.

If you shoot into a garage or supermarket with fluo tubes on the ceiling and you bring halogens (very orange/yellow light), foreground and backround will still look very different, but it is less noticeable (or more acceptable).
You can correct a light using filters, but filters do not bring "up" a color, they filter "down" other colors, so there is a loss of light output. This is particularly important for led light where power output is already limited.
So if you got a 50W led light that is too blue, putting an orange filter will not bring more orange , but remove some blue and green, so your total output will be a lot less than 50W.

Another consideration is CRI. CRI is a measurement of how close each color is properly wheighted. Some light sources are continuous (like halogen), other
are just emitting "bands" like fluorescent tubes.
The result is if you shoot a color chart, some color will render ok, and some color will be wrong (render as different color or grey).

another details is hardeness of light, or if you prefer, the abilty of light to cast shadow.
a hard light will create razor sharp shadow, a soft light will at best create almost no shadow.
Some light source are naturally soft (like fluo tubes) and are difficult to make hard.
Some others are hard by nature (like led or halogen ) but can be soften with filter (but again, loss of power output is predictable )

So the rule is: if you can supply your own light on all the scene, there will be no need to color-correct.
if you have to deal with uncontrolled light source, you better need to color-correct your own light to match (or the reverse).
 
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ok

thanks very much!! but practically, how can I color correct my scene?

anyway I will try to look further on my own and then try to buy some lamps adn do some try

thanks very much
 
practically, the easiest way is to use the same type of light that you will find on location. If it is an appartement with regular bulb (yellowish light) , use same bulbs (or halogen) . If it is in a supermarket with fluo tubes, use fluo tubes(or led).
I doubt there is a single movie on earth that use the colors as originally shot.
even film was tricky to obtain the right color, at the extend that early B&W films where using "false" colors (for example many costumes where red instead black, because red turned as better black).
If you can find some pictures taken from "gone with the wind" and compare with the movie, you would be really surprised.
In video , some people are color correcting with "warm cards" to make the white balance. For example you trick the camera by making a white balance on a white-pink card. So camera will try to turn that color to white, giving a greenish look by lowering red sensitivity.
You better to do that in post, because there is no limit here.
Something that is more difficult to correct is constrast, so do not care about color, just make sure the scene is well lit and shadows are properly controlled.
 
ok thanks

I will try and let you know

I am going to shot a promotional video for a drummer friend of mine.

it will be an excercise for me but at the same time I hope it comes out as much professional
as i can

and by the way tell me: I am going to rent 2 dvx 100 (probably BE)

is it possible to plug a lcd pc monitor via vga as an external monitor?
 
Check it out!

Check it out!

There are some lights out there that you can switch between color temps.

Some are with switches, some are with color correction filters over the lights.

There are some LED lights that you can actually dial in the color, not switch between.
 
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