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shooting flash on a cloudy day

Discussion in 'General flash photography, lighting, and technique' started by 3LPCPhotography, Aug 15, 2009.

  1. 3LPCPhotography

    3LPCPhotography

    467
    Oct 30, 2008
    Canada
    Hi,

    I'm going to be shooting flash for fill on a cloudy day. Any recommendations on filters to use so my white balance is consistent for color for nearby flash filled objects and futher off objects lit by the cloudy skies?

    Tom
     
  2. WayneF

    WayneF

    Apr 3, 2006
    Texas
    Not a clue, but not to let that stop me.. :smile: Normally the warming effect of daylight flash in cloudy background seems a good thing.

    But to filter the flash to match cloudy would be blue in some degree, to match the blue cloudy light, and to allow Cloudy white balance. For opposite example, incandescent is orange, and we use an orange CTO filter on the daylight flash to match that, and to use incandescent white balance.

    See Wikipedia about Mired, which number is equal to 1 million divided by color temperature in K. It says as an example:

    In photography, mireds are used to indicate the color temperature shift provided by a filter or gel for a given film and light source. For instance, to use a tungsten light (3200K) in natural light (say, 5700K) without introducing a color cast, one would need a corrective filter or gel providing a mired shift of
    b94b5bc9bdb285592a2f13662a26e9ad.png
    Subscribe to see EXIF info for this image (if available)

    This corresponds to a CTB (color temperature blue) filter.


    So plug in your daylight flash numbers and cloudy day numbers, to get the necessary filter shift in Mireds.

    Rosco CTB filters 3202, 3202, 3203, 3204, 3206 are blue filters intended to convert tungsten lights to daylight, and they ought to convert daylight flash to cloudy blue too. They are degrees of blue, to shift the light color towards blue. Just blue, not dedicated to incandescent even if these just happen to be shown for that common use, but they are calibrated in mired.

    3202 -131 mired shift, 3200K to daylight (darker blue filter - called full blue)
    3203 -100 mirid, 3200 to 4700
    3204 -68 mirid, 3200 to 4100
    3205 -49 mired, 3200 to 3600
    3208 -30 mired, 3200 to 3500
    3216 -12 mired, 3200 to 3300K (lighter blue filter - called 1/8 Blue)

    Those would be my first try. Plug in your flash and cloudy K numbers to determine Mired shift needed. Then bracket tests with filters on each side of that. Again, these are a blue shift, calibrated, but not limited, to incandescent. You are looking for an X amount of mired shift towards blue. Your cloudy surely varies greatly, your flash varies some, and here is a good link that says you want a shift of around 5000K to 8000K, maybe.

    This Rosco swatch book http://www.bhphotovideo.com/c/product/45184-REG/Rosco_950SBCNG0103_Cinegel_Swatchbook.html
    contains all these CTB filters (and a great number of others), of size usable on a Nikon speedlight flash. Very usable on a Nikon flash. Just use masking tape at the ends on the side of the flash, and in particular, that lets them stand out forward maybe 1/32 or 1/16 inch. If actually touching the flash lens, they may melt. If standing out away the slightest amount, they will be OK.

    This one http://www.bhphotovideo.com/c/product/45189-REG/Rosco_950SBLUX0103_Roscolux_Swatchbook.html has others, and possibly they may be in there too, but am not sure. I am sure they are in the Cinegel swatch book. These swatch books may be free directly from Rosco, but they will take a very long time to get, whereas B&H ships promptly.

    EDIT: Just found them. These same CTB filters are in both Rosco swatch books.
     
    Last edited by a moderator: Aug 15, 2009
  3. Plumbergeek

    Plumbergeek

    972
    Sep 1, 2008
    SW Georgia
    LOL, Now you did it! You got Wayne to answer, now don't you feel dumb? I know I do......
    I am of couse just kiddin, it's just Wayne REALLY knows his stuff and it goes way over my head! :wink:
     
  4. WayneF

    WayneF

    Apr 3, 2006
    Texas

    Sorry, I was just trying to say one of the CTB blue filters, and for a speedlight size, simply get the swatch book to have many inexpensive choices to test which one for this situation.

    I guess I do complicate it, but to me though, it seems much less complicated to have the simple rule to determine which CTB filter ought to be correct. :smile:
     
  5. Plumbergeek

    Plumbergeek

    972
    Sep 1, 2008
    SW Georgia
    I was just poking fun at ya Wayne! I love your detailed responses. I'm envious of your knowledge.:redface:
     
  6. 3LPCPhotography

    3LPCPhotography

    467
    Oct 30, 2008
    Canada
    Wayne, your answer is really great. What I can do is use the live view and WB tempeature adjustment to fine the WB I like. Then a quick bit of math to find the number I need. Agree I may have to do some test shots to figure out which filter side of blue I need to compensate for the flash kelvin temp. Thanks for a great answer.

    Tom
     
  7. Rooz

    Rooz

    Nov 22, 2008
    Sydney, Oz
    tom, i think alot of this depends on your creative expression. what sort of cloudy is it, (warm suny sunset cloudy, dark, moody cloudy etc) and what sort of feel you are trying to achieve.

    FWIW, i try and just get the background right where i want it with WB and then adjust the subject colour according to the mood i want. for portraits i like to use a warm filter to cut down the cool light from flash. so i use CTO's, either 1/4, 1/2 or full cut.

    carry a stack of filters with you and then try a couple to see what you prefer.
     
  8. I always have a 1/8 CTO filter on my flash with the White balance set for auto for outdoor bright daytime shots.

    Night it's basically 1/1 full CTO with usually between 2500-3200k.

    But by default a CTO filter is always on my flash no matter what.
     
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