Can someone explain color cast to me??!!

Discussion in 'Beyond the Basics' started by freddyfries, Jan 16, 2006.

  1. freddyfries

    freddyfries TPF Noob!

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    Hi there,

    I am relatively new to photography and am working with a D100 set up with Adobe RGB II, using the standard curve and shooting in RAW. At the moment I am increasingly taking more studio pictures with two Bowens Esprit 500w lamps. Every image I take has a brutal color cast within it. I can correct this fairly easily in Nikon Capture Editor or Photoshop, however I don't understand why this is?? Have I done something wrong?

    To see an example of what I am dealing I have put two images in before and after status at the following address

    http://www.freddyfries.com/colorcast.htm

    If any one could please provide a bit of further information regarding this issue I would be most gratful

    Thanks a lot
     
  2. Rob

    Rob TPF Noob!

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    The colour cast you have shown in the example is typical of using tungsten bulbs. The colour temperature of a lightbulb for your rig should be listed on the box. That said, when shooting in RAW, you can adjust the balance to even the picture out.

    As I understand it, the Bowens Esprit was supplied with 500W Halogen flash bulbs, which should be daylight balanced. However, if you have non-daylight bulbs, then you would get exactly the results you've shown, which can be corrected post-processing.

    There really are only three possible causes - the colour temperature of your lights, the camera's white balance (not applicable in RAW), the colour settings you use in PS. If you PS is calibrated correctly, which presumably it is from your example shots, then by elimination it has to be the temperature of your flash bulbs.

    Hope this helps

    Rob
     
  3. markc

    markc TPF Noob!

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    My understanding is that when shooting RAW, you still set the white balance, which it stores as info, but it doesn't change the image data. As Rob said, you can change it after the fact.
    Are you editing in RAW, or are you converting first? If you are converting, the software is probably taking that color balance setting and applying it to the image. If it turns out your bulbs really are daylight, you might want to look at your workflow.
     
  4. freddyfries

    freddyfries TPF Noob!

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    Ultimatley it is not a great problem. I shoot everything in Raw and then edit it in Nikon Capture Editor before taking it into Photoshop to make any final adjustment before printing. I just find it rather extreme what comes direct from the camera! I certainly feel I couldn't show it directly to a customer! (not that I have any, however one day that is the plan) I felt one of the great things about digital would be the instant feedback. At the moment everything is a rather muddy white that requres batch processing to get it looking half reasonaable. It could be the bulbs, how would I be able to test this? and should I change the white balance setting for my flash - or the bulbs?

    Any help would be great!

    Thanks
     
  5. Digital Matt

    Digital Matt alter ego: Analog Matt

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    Why don't you do a custom white balance with a white card? Just place a white card, or white paper/foamcore etc, right in the scene under your typical lighting. You can have the model hold it if you are doing a portrait, or just prop it up in your still life scene. Fill the frame with it and take a picture, then set that picture as your custom white balance. Then be sure to actually set the white balance to custom. I don't use Nikon eq, so I can't tell you specifically how to do it, but it should be similar to that.
     
  6. freddyfries

    freddyfries TPF Noob!

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    It seems (from looking at Nikonians forum) that most people opt for shooting RAW and then fixing it in post. I guess I shall have a go with some custom setting and see what happens

    Thanks for all the suggestions and advice
     
  7. craig

    craig TPF Noob!

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    It has been my experience that custom settings or presets work best. In this case you should be using a Tungsten WB. Shooting RAW is definitely the way to go. It is important to get it close out of the camera. less post processing leaves more time for shooting.

    Check out the specifics of colour temp. It really helped me to understand what is going on.
     
  8. freddyfries

    freddyfries TPF Noob!

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    This is all good information. I guess what I was aiming for was trying to get as acurater information as possible from the initial image, therefore reducing that post production time (which I must say I don't mind, however, the more I have to do, the more I wonder why the hell was this not right from the beginning!)

    Does anyone have any recommendations regarding reading on colour temperature? (eg books on digital lighting or websites that have been imformative?)
     
  9. Digital Matt

    Digital Matt alter ego: Analog Matt

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  10. zedin

    zedin TPF Supporters Supporting Member

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    I would definitly suggest using a custom WB and measuring for the light if you are going to be shooting for some time in the same conditions. I did a few shots in my room using auto, tungsten, and a custom WB off a grey card (love nikon for letting me set it off a grey card). I definitly got a much better pick using the custom WB. Auto was horrid and had a nasty yellow cast and tungsten wasn't bad but not nearly as good as custom.
     
  11. Rose

    Rose TPF Noob!

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    yes i find also that the canon 350D 's auto white balance isnt that great ( i had a sony cypershot previuosly and it was great:was able to set manual white balance with one click). with the canon its a bit more work: taking a picture, then importing that as your custom white balance...

    i guess thats part of the reason were shooting RAW!
     

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