Problems using measured white balance

[tibbs2]

I am having trouble taking pictures of my tank using measured white balance.

I am inserting a digital grey card in the tank and then measuring the WB with my camera (Nikon D50). My results are less than spectacular. All my pictures have a very red hue to them. Is there anyone here who knows what I'm doing wrong or can give me some tips? My fellow club members seem to have the same trouble when they've tried it.

Thanks,
Chris

[gregr]

What kind of lighting do you have? A red wb would mean overly green lighting, which doesn't make a lot of sense unless you're using straight flourescent lights. Have you tried any of the preset wb settings? How does auto wb look to you? What software are you using by the way? Mild color casts can be corrected fairly well in Photoshop. One more question- does that camera have raw/nef mode? Another question Can you post a picture or two?

[tibbs2]

I am using 4-54 watt T5 bulbs. Two 12k Aquablue and two Blue+. I guess it is more than a tint of red. The pictures are very red. I just can't figure it out. Do I need to use a white card instead grey to measure the WB? I shouldn't think so.

The auto WB casts everything in a blue light which isn't accurate. I do process my images in Photoshop /with RAW NEF files.

I would rather measure the balance when taking the picture than trying to correct it in Photoshop. I will post a few examples when I am home this evening to give you an idea.

Thanks,
Chris

[gregr]

I've seen that pinkish orange-ish reddish colorcast from T-5 bulbs too. Gray or white [card] should work but if you've been using gray give white a try. As an excercise you could take a pic with the white card in the shot and in Adobe Raw Converter use the eyedropper on the white card and see exactly how the color temp/tint change. Then you'll know just how far outta whack the camera is (not that it's the fault of the camera). You can also sample a black area with the eyedropper to adjust color balance-- from image>>adjustments>>levels. You can do white point adjustment as well as black- very helpful.
A lot of the pictures I take look pretty mediocre out of the camera but after a click or two in the raw conversion software and Photoshop they look pretty darn close to reality. That used to bug me a lot but now it's just another step in the process and it goes quick once I figured out what adjustments to make.

[Chris Witort]

here is a fix I psted in another thread that you could use to fix your images. In the other situation they were using an expodisc to get their 18% gray image but using a gray card will work the same way. Getting the right color with reef photos isn't easy. I struggle with it myself. If you use the expodisc to set your white balance you will have an 18% gray image to work with in photoshop. I'm not sure about your version but you should be able to open the subject photo and the image you made as your WB shot, go to the image pull down menu, then adjustments, then curves. you should now have both photos open and the menu for curves. Click on the subject photo to highlight it, now click the center eyedropper in the curves window, this is used to set the gray point. now place the eyedropper over the expodisc image and click on it. this should change the color blalance in your subject image. If the expodisc image got a good exposure your subject image should be closer to the right color rendition!