Critical White Balance

[Joseph Chiang]

I'm starting a new project where I'll be photographing antiquities, some of which are glassy and highly reflective and made of stone or glass. There are some very subtle color variations that are critical for us to capture and therefore, white balance is critical.
We want to capture surface texture, translucency and color (difficult to capture balance all 3 attributes).

Additional information
Lighting some of these objects will be very difficult because there are some very intricate designs in these objects and some have highly reflective surfaces.
We're contemplating using flash merging techniques, maybe even HDR to help capture every nuance of these beautifully made works of art.

In a previous post, Andrew Rodney and Drew were going back and forth as to best method for white balance.

My questions are, anyone out there experienced in this matter where white balance of 3 dimensional works of art is critical? Would it be better to use something like the Gretag Macbeth Colorchecker, or the new Color Passport (since some of the pieces we are photographing are quite small) or the Color Max?

Does the new Color Passport have as good a white point as the Colorchecker?

Interested in other's experiences......

[KevinStecyk]

Originally Posted by Joseph Chiang

My questions are, anyone out there experienced in this matter where white balance of 3 dimensional works of art is critical? Would it be better to use something like the Gretag Macbeth Colorchecker, or the new Color Passport (since some of the pieces we are photographing are quite small) or the Color Max?

You might wish to purchase and then watch -

Best Sellers : Zen Cart!, The Art of E-commerce

- L-L Guide to Raw Processing for CS 3 (assuming CS4 tutorial covers it as well, though you should verify)
- Fine Art Print Tutorial

Both of the two referenced videos discuss how to calibrate your camera to a Gretag Macbeth Colorchecker. For those that have a need for color fidelity, this might be important to you.

[drew]

The first question is, how many light sources are going to strike the objects? Is ambient light going to be part of the equation, or only controlled lighting sources?

Regarding lighting and exposing, you certainly may have some complexities to work with.

"However, regarding white balance, it is a fairly simple equation. You need to make sure you get the best overall average reading of all light sources striking the area of interest on the object(s) you are photographing."

If all the lighting is going to be controlled, and if all the flash heads are a similar color temperature (highly recommended), then it is a fairly straightforward proposition. If the heads are not all a similar color temp. then it becomes a bit more of a chore, but not much.

In short, the object you are measuring is not really relevant, only the light sources that illuminate it should factor into the equation.

Now, if you try to use a gray card, or a color checker type device, or even the MAX side of the MAX, you would need to ensure that there is no color contamination reflecting off of the objects (or anything else e.g. the background) onto the neutral portion of your reference card/ device.

[Joseph Chiang]

We'll be shooting in a darkened studio, so little or no ambient lighting.
Right now we have a couple of Quantum flash units and various light modifiers, including softboxes and blackout cards, white cards and mirrors.
We also have Nikon speedlights.
Are the color temperatures of these different types of flash units that different?
We have contemplated purchasing studio flashes that have finer power adjustment capability.

[Joseph Chiang]

Also plan to process in Lightroom, as much as possible.

[Joseph Chiang]

Kevin, thanks for the video tutorial suggestions.
Our studio's been kind of tight on funds lately and this new project is a subject matter we've never shot before but may grow into something signficant with time.
I think I've seen articles in DPP or Lee Varis' Skin book that talks about calibrating one's camera to the light source. You think either of those sources gives the same instructions?

[drew]

Originally Posted by Joseph Chiang

We'll be shooting in a darkened studio, so little or no ambient lighting.

One variable gone. Cool.

Right now we have a couple of Quantum flash units and various light modifiers, including softboxes and blackout cards, white cards and mirrors.
We also have Nikon speedlights.
Are the color temperatures of these different types of flash units that different?

in a word, yes. while the color temps may not all be that much different, they could be. the hodge podge of various modifiers, softboxes, blackout cards, etc now add a lot of variance back into the equation.

We have contemplated purchasing studio flashes that have finer power adjustment capability.

The power isn't really a concern for proper color balance, if you are using a reflective type measurement device (eg. the ColorRight MAX, etc.) What would be nice is to have all the heads and softboxes/ modifiers be from the same manufacturer(s) with identical model number(s). Nice, but certainly not absolutely essential. With mixed lighting you are going to have to work a bit more to get the results you want. Let's suppose you light the front of the object with some sort of light/ modifier combo (let's call it light source A) that yields kelvin reading A, then you light the back of the object with light/ modifier combo B. Well, unbeknownst to you, the back light combo is 400 degrees cooler (kelvin) than the front light source combo A. In this instance, if you simply measure and balance for the main light combo A you will end up with a blue tinted backgorund light source. Is this making any sense?

Now, imagine adding your third and/ or fourth light source to the mix. Starts to get a little complicated fast, no.

So, using the gear you have, your best option is probably going to be to make certain that you place the MAX, or other neutral reflective device, in the scene so that it grabs a bit of light from all the light sources illuminating the object(s) of interest.

With such a mix your best bet is to get the best "average" reading from all the light sources combined. This is where you would probably be better off with one of our "transmissive" devices like the original ColorRight, rather than a simple reflective device like a gray card or a white card, regardless of neutrality rating.

A transmissive device gathers light from a larger area than a reflective approach can muster. Our newest ColorRight Original product gathers light from a fairly wide angle of coverage. You may also consider the Expodisc product which isn't very neutral and doesn't work well in low light, but does successfully provide a fairly wide angle of coverage (according to Doug Kerr about 110 degrees).

With either of these two products you would hold the device over the lens of the camera, and then place your camera in a position so the flat face of the device is able to pull in light from all the light sources at once. This should provide you with a workable overall average color balance reading.