White Balance Database

Hey, guys -

I'd like to assemble a page where you can download jpg images for custom white-balance with different strobes. I use an Expodisc for land-based whitebalance, and will do some experimentation with the DS-125 next week when I get home from San Diego. I'll likely just shoot -- in complete darkness -- with the DS-125 and the expodisc to get the image. Then, I'll post samples using the DS-125 with auto WB, cloudy WB, sunlight WB, speedlight WB, and the custom WB. I'd like to get something like this for all of the commonly used strobes out there.

Will different types of water affect the white balance from strobe sources? Do I need to do this in a swimming pool?

Anyway, we could even have an image to use for custom white-balance for strobe-less forays into uw photography. Granted, they won't be nearly as effective as a red filter is, but it would be better than using "auto." Maybe even for different times of the day and types of water! (clear, blue water vs. nasty green water, etc. .

Thoughts?

I like the idea. With all the talk on RAW and the ability to adjust for it I am quite curious as to the strobes and the appropriate settings.

Good Idea.

I looked at Expodisc to try to understand what you were suggesting. Not sure I fully understand the process, but that's never stopped me from commenting before! Actually, I understand the device, but the resulting jpg must be a D60 thing???

Perfectly clear water is a color filter that has a peak somewhere in the blue to blue-green range. As you increase the turbidity of the water, the peak gets lower in frequency, First it turns green, then eventually yellow (brown). In addition, the color balance of sunlight changes throughout the day as I'm sure everyone knows. Finally, the angle of the sun as it strikes the water changes the color balance of the light that passes through the boundry.

Most of this doesn't effect Eric's idea of balancing strobe light, of course, but the turbidity of the water and the length of the light path do. Shooting in a pool would give you a well-understood reference but it wouldn't represent actual dive conditions.

It is my understanding that each foot of clear water provides the equivalent of (as much as) -5 mireds of temperature shift and about 2CC of green. I don't think you'll get universal agreement on that, but it is consistent with both UR Pro and Aquacolor filters. These units are standard for photographic filters but I can explain them if anybody likes. Essentially, clear water forms a blue filter but allows a little too much green through.

You can see that predetermining white balance in the way Eric suggests would be useful above water, but below water it would only be accurate for water similar to test conditions, for strobe light only, and for a single water path length. I like the idea, but I don't think it would be as useful as you'd like. I'd love to see the results for various strobes, though. It would be "illuminating".

Now for macro shooting where you have strobe light only and a water path length of, say, 4 feet, this will probably work. The trouble is, the water is contributing only about -20 mireds and may 5-8CC of green. To offset that with filters, you'd use the weakest magenta filter available along with an 81A. In white balance terms, if the strobe were 5500K, the light entering the lens will be 6200K. Not a great deal of difference. You could just create your custom white balance jpg out of the water and add an 81A to your macro lens. I personally think this is a great idea, but I will be using an 81EF. The reason for that is material for another post!

Sorry for being so yakky.

Let's talk about this one some more.

My next trip is in 2 weeks and I can do some white balance tests - no, take that back - I can't do it in my Ike housing.

On the other hand, when I do a RAW conversion, the default color temp is 6500k - this is for the Fuji RAW converter LE. You can set it to whatever you want with the RAW converter EX. Do you want me to convert some RAW files at different color temps and post the results?

Eric, I shot all RAW at the Coronados - and we've got the same strobes. Might be interesting.

Cheers

James

James, can you not disable white balance adjustments in your conversion software?

BreezeBrowser displays Nikon RAW images. Can it do Fuji also?

Hi Craig,

Yes, the camera comes with Raw Converter EX and Raw Converter LE - when using LE, it just does a quick conversion using the camera defaults (ORG, ORG, STD).

I use a just-right-click Windows plugin that lets me view the RAW files in Windows Explorer - it's pretty sweet. I don't have to open a third party file browser at all and it displays EXIF info too!

Cheers

James

Very cool. I think it's important to see the raw file knowing that it hasn't been corrected in any way.

Incidently, in order for a camera to have a "6500K setting", or any other for that matter, it has to know where it is coming "from". I'd like to know what that is for the various cameras, too. I bet the authors of the RAW file converters know what that is.