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  1. #1

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    Flash Color Temperature Issue

    I'm starting a new project soon that will involve shooting interiors with Portra 400 sheet film and flash. Prints will be RA4. I checked the color temperature of my flash and found that it varies from about 4400K to 4800K depending on the output. The meter suggests using an 82A or 82B cooling filter to balance the flash light. The specs for portra 400 suggest no filtration for daylight or flash. I'm wondering if 4400K to 4800K is close enough to the 5500K this film is presumably calibratred for? Is it impotant to filter in this case? Thanks in advance for your advice...

  2. #2
    ic-racer's Avatar
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    Quote Originally Posted by Pasto View Post
    I'm starting a new project soon that will involve shooting interiors with Portra 400 sheet film and flash. Prints will be RA4. I checked the color temperature of my flash and found that it varies from about 4400K to 4800K depending on the output. The meter suggests using an 82A or 82B cooling filter to balance the flash light. The specs for portra 400 suggest no filtration for daylight or flash. I'm wondering if 4400K to 4800K is close enough to the 5500K this film is presumably calibratred for? Is it impotant to filter in this case? Thanks in advance for your advice...
    I'd think you should be able to adjust the coloration when printing. If you are going to shoot a gray card and match that, don't alter the flash output after that.

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    I'd say generally that it's going to boil down to personal preference and whatever makes your printing easier.

    The wild cards are the ambient light and the surfaces you'll be bouncing off.

    Another option you may consider is using gels on the flash gun(s). If for example you are using a nikon speed light in "A" mode this can get you better exposures because the flash gun measures it's own output rather than the camera. The flash gun doesn't "see" the filter.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

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    There will not be any ambient light as the flourescents will all be turned off prior to exposure. Also, I'm using speedotrons and I've thought about geling them instead of filtering the lens....

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    markbarendt's Avatar
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    Sounds like its time to test a few sheets.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  6. #6

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    Run a roll thru a 35mm or 120 format camera, lower cost than a few sheets of film.
    Bob

  7. #7
    Leigh B's Avatar
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    Quote Originally Posted by Pasto View Post
    I'm wondering if 4400K to 4800K is close enough to the 5500K this film is presumably calibratred for?
    No. 4400K is halfway between daylight (5500K) and incandescent light (3200K).

    Filtration is certainly appropriate. You can bandaid it after exposure, but there's no substitute for getting the negative right in the first place.

    You should check your strobes. They're way off; should be 5500K-5600K.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

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    I'm wondering if it's my color meter. My metz 45CL4 comes in at about 4800K......

  9. #9
    Leigh B's Avatar
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    Quote Originally Posted by Pasto View Post
    I'm wondering if it's my color meter. My metz 45CL4 comes in at about 4800K......
    It's difficult to get a consistent color temperature reading.

    I just took my Gossen Color-Pro 3F outside to read sunlight, with thin clouds covering most of the sky. It's 4PM daylight saving time here.
    Depending on exactly where I pointed the sensor, I got readings from 5780 to 5910. That number would have been lower in direct sunlight.

    The CT reading is actually just the ratio of red to blue. The green component of white light is not evaluated at all.
    Most modern CT meters include a separate channel to read green and suggest magenta/green filtration to balance it.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  10. #10

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    I hear you Leigh. I just stepped outside and took some readings with my Minolta Color meter II. I got between 5200 and 6000 depending where I pointed it (It's sunny with no clouds today here). My meter is the older version that requires the incident sensor head to be swapped with the flash sensor head for flash readings. I was just surprised that my speedotron 102 flash heads were so far away from 5500. The readings from the flash heads were quite consitent from burst to burst. I just sent email to speedotron to see what they think. My understanding is that these flash heads should measure closer to 5700K, and that the new UV coated bulbs are closer to 5500K.....

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