The above Ad will no longer appear after you Sign Up for Free!

Color Correction

Discussion in 'Lighting and Electrics' started by Pie4Weebl, Jul 17, 2007.

  1. Pie4Weebl

    Pie4Weebl Well-Known Member Fight Leukemia

    Messages:
    2,441
    Likes Received:
    341
    Location:
    New York City
    So I'm visiting a good friend of mine and her dad is currently working on a music video for band, knows I do lighting stuff and wants to put me to work, im not entirely sure to what capacity, but I would rather too much for what I need to do that to little, so here is my question, how do you use color correction, Do you gel it in with every light or just the ones that would be no color? What are the different types and how are they different? If I end up doing a design for a music video thats like a vid of a performance any tips for lighting in that situation.
     
  2. Grog12

    Grog12 CBMod CB Mods Premium Member

    Messages:
    2,615
    Likes Received:
    172
    Location:
    Denver, CO
    From what I know of lighting for film you typically use color correction to A)balance the color tempature of different sources. and B)Match the film speed.

    For instance you have 2 HMI sources and a incandescent source you might use CTB to match the incandescent to the HMI or CTO to do the opposite.

    Full CTB Shifts from 3600ish K to 5700ish K
    Full CTO Shifts from 5700ish K to 3600ish K

    They are available in in 1/4 1/2 3/4 and full. Full obviously doing the full shift and the 1/4 ect doing a partial shift in color tempature.

    Another thing to keep in mind is that typically they don't use dimmers in film lighting....they use...crap what are they called...basically pieces of scrim that cut down the light out put...available in singles and doubles. This is meant to keep you from Amber shifting any of your lights.

    Another good tool is Neutral density.

    Approach the design as you would any other design...but make sure to figure out how its being recorded...is it film? Is it digitial? Is it HD?

    If its film that's going to impact what color correction you use based on the film the DP is using.

    Digitial you might get a little more leadway but not much.

    A lot of the basic design concepts are the same but make sure you research how color tempature is going to affect film and expourse before getting into it.
     
    Pie4Weebl likes this.
  3. gaffer240

    gaffer240 Member

    Messages:
    26
    Likes Received:
    0
    Location:
    Beaufort, SC
    You generally use color correction to match inside lighting to outside eg Rosco 3204 or others in that series or outside light to indoors eg as Rosco 3401 (roscosun 85).
    Lots of options here. If working in Daylight and you are indoors and you are useing 3200K lights then you need to color correct the lights to sunlight, or you could cover the windows with 85 or 85B(if it is still around) and convert outside sunlight to 3200K.
    That said you do not have to worry about color correction if you are shooting indoors with no outside light, or outdoors at night as the white balance on the camara should handle it. In either case, if you are dealing with a camera filter wheel or adjustment, just set for indoors or 3200 K and have fun.

    I have found that if all you are shooting is colored lighting on a group and no sunlight is present then the indoor settings will work fine and catch most of the color
     
  4. SteveB

    SteveB Well-Known Member

    Messages:
    4,028
    Likes Received:
    771
    Location:
    Brooklyn, NY
    You also use color correction indoors to balance fixtures that have different color temperatures - I.E. a Source 4 incandescent at 3000-3200 degrees Kelvin, balanced to an arc lamp moving fixture and/or HMI or Xenon follow spot at 5600 degrees Kelvin. The basic concept is that the video camera will want to "see" white, and may assume that the color of an incandescent light at 3200 kelvin , with no color filter, is reference white. Adding in an HMI or xenon follow spot, with it's higher color temperature, will result in the FS causing a performers face to look very blue, thus the need for color correction.

    Note to all that the original post was specific in using "Video" in the description, thus I'm assuming that film speed is not going to be an issue (best check though !).

    I use color correct in my Xenon follow spots to get the color of the lamp (which is something like 5600 degrees Kelvin) closer to the rest of the incandescent sources. Rosco and Lee make assorted 1/8, 1/4, 1/2 and full CC's (3204, etc.. in the Rosco line) but will sometimes simply throw in a stock R02 or R18, which is close enough to look good on video.

    SB
     
    Last edited: Jul 17, 2007
    Pie4Weebl likes this.
  5. Grog12

    Grog12 CBMod CB Mods Premium Member

    Messages:
    2,615
    Likes Received:
    172
    Location:
    Denver, CO
    Funy that's why I assumed it would be and issue :lol:
     
  6. Pie4Weebl

    Pie4Weebl Well-Known Member Fight Leukemia

    Messages:
    2,441
    Likes Received:
    341
    Location:
    New York City
    ok, so assuming indoors with no exterior light and various sources of light is it better to correct to a higher temperature or just what you have the most of?

    And thanks for your input so far its been helpful.
     
  7. Grog12

    Grog12 CBMod CB Mods Premium Member

    Messages:
    2,615
    Likes Received:
    172
    Location:
    Denver, CO
    Price wise what you have the most of

    Recording wise....well its a matter of taste...I'd proably go for a high color temp but that's just me.
     
  8. SteveB

    SteveB Well-Known Member

    Messages:
    4,028
    Likes Received:
    771
    Location:
    Brooklyn, NY
    You correct any light that is not "white", that needs to be, if the light is used as a Key light - I.E. a primary source for the camera. You can go nuts trying to correct all the assorted higher kelvin lamps that suddenly become Key lights as a result of the camera(s) moving around a lot - side shots, back shots looking towards the audience, etc...

    This is where a TV/Film lighting director/gaffer - DP earns their pay, figuring out where the camera shots are going to be, then designing Key and Fill as needed for all the shots. It's a tough balance, as you may want the arc source flash & trash ML's to keep their "whiter" look, as it's punchier and flashier. Problem comes in when one of those "Effect" units suddenly is focused on a performer with a camera in the same angle. The "Effect" unit, without color correction (to keep it punchy and flashy) is now in the wrong color to be a Key light. That can be annoying if seen repeatedly, but sometimes you can get away with it if it's random.

    One thing that's useful is to determine in advance, where the camera(s) are going to be, if there's more then one. Then plan on Key lights from incandescent sources to cover those angles and not rely on arc lamp ML's as keys, but to keep them off the performers if possible.

    SB
     
  9. Van

    Van CBMod CB Mods Premium Member

    Messages:
    5,865
    Likes Received:
    1,185
    Occupation:
    Project Manager, Stagecraft Industries, Inc.
    Location:
    Portland, Or.
    "Scrims" is what some of them are called, Scrims, Screens, flags, cookies, and cutters. here's a link for anyone interested.
    http://www.dtcgrip.com/Rentals/rentalcover.htm
    Usually when you rent a "movie Light" you get a little box, or sometimes bag, called a scrim bag. It's typically filled with little pieces of screen that will fit into the color holders. A lot of times the screens will be stuck together because of the Gaffers love of "Snot Tape".
    There are also some other peices of fabric stretched on metal frames, usually white or silver called "Bounces". A bounce allows for dynamic filling by a first unit gaffer whilst the camera is rolling.

    Dimmers are occasionally used, but typically in the form of an autotransformer, and again usually for color matching.

    You don't use color frames in the movies either, you use C-47's or snot tape.
     
  10. Grog12

    Grog12 CBMod CB Mods Premium Member

    Messages:
    2,615
    Likes Received:
    172
    Location:
    Denver, CO
    Cookie was the term I was trying to remeber thanks Van.

    The way I typically saw color added to a light was via barndoor.......Which is to say the barn door goes in the color slot, then you Clothes pin a full sheet of gel to the the barn doors.

    Ah but you ask what if I need to cut the light?

    You add a flag...on a separate stand.....


    ....Yeah...movies...oof.
     
  11. Van

    Van CBMod CB Mods Premium Member

    Messages:
    5,865
    Likes Received:
    1,185
    Occupation:
    Project Manager, Stagecraft Industries, Inc.
    Location:
    Portland, Or.
     
  12. Grog12

    Grog12 CBMod CB Mods Premium Member

    Messages:
    2,615
    Likes Received:
    172
    Location:
    Denver, CO
    I once asked a DP why they didn't use ERS'. He told me it was because they weren't as flexible as Freshnels
     
  13. JD

    JD Well-Known Member

    Messages:
    4,030
    Likes Received:
    1,258
    Location:
    North Wales PA
    The video world was designed around 3200 Kelvin, tungsten based lights. Needless to say, we have come a long way. Your core color temperature can now be set almost anywhere, B-U-T I can tell you with authority that when video cameras are aligned in the shop, everything is done at 3200. (I used to do this for a living.)

    So, the "white" balance of the camera can be changed either electronically, or by the addition of correction filters. Electronic is better as it does not introduce the spectrum errors which filters do. So, you chose your camera's white balance. Lets say you chose 3200. Now, you have to correct any lighting that is not running at 3200. (Unless you are intentionally introducing a color shift.) Tungsten is the only full based spectrum light that comes close to the sun as far as not having spectrum "holes" (Even though the sun is a quite a different color temperature.) If you are balancing tungsten to daylight, correction filters work pretty good. Problem is, you may want to balance higher color temperature lights down to 3200. (like HMI) Here's where the trouble starts. Google for spectrum results on HMI and you will see that it, as well as most HP lamps, has a very uneven spectrum. Next, try to find any full spectrum test results on the correction filter gel you are using. (hard to find) The slopes tend not to be to pretty. For the most part, to the naked eye, the correction looks pretty good. Our own eyes only see three colors. Life is full of colors that are in-between. If a color lies in a peak or valley in the spectrum of the light or filter, the result from the camera can be quite unexpected even though cameras only see three or four colors as well. (RBG or CMGY) It's kind of like resonance patterns in sound equipment.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice