Custom White Balance Debate

[ivgonzalez]

I have seen several photographers use the 18% grey cards used for this and many use the white card for this purpose. I would like to start a discussion as to why one way over the other, cuz I don't know.

Anyone?

[ivgonzalez]

So I guess there is no debate... and it does not matter or no one knows?

[kenw]

White balance is set with a color neutral source, in the old video days (and some camera makers still) most recommended using a WHITE card. Anything that reflects all colors in equal amounts is color neutral. But white reflects MORE light, so it was often recommended.

In fact somewhere between the 10d and 20d, Canon changed their minds and went from recommending a white source to using an 18% grey card.

For years I used a piece of laminated (to keep it clean) 98% white photo printer paper handy for just such purposes. Now however, I use the presets almost exclusively.

Some folks claim difficulty using a white card (if improperly exposed, you won't get the right reading, and proper exposure of white things can evidently be tricky for some..., and the definition of white leaves something to be desired), and since technically you only need a color neutral source, a grey card (any % will do) serves the purpose.

Since grey is a blend of black and white, and has no color/tint component by definition, it serves the purpose of being color neutral. As do white and black, altho black is a bit tough to get a reflective reading from.

And since 18% grey cards are often used for exposure metering, you can kill 2 birds (exposure and white balance) with one device (a single 18% grey card).

For me the only debate is that some INSIST that white balance MUST be set with a 18% grey card, which is nonsense, altho it is convenient and does no harm.

[shutterdrone]

Over at Luminous Landscape, he has an article about "Exposing to the right" with digital cameras, it's dated a few years, but I've started using his advice about using a pure-white source as an exposure meter, rather than a mid-tone source. (I do primarily black and white, not color, so WB its self is of little use to me, and if I wanted it, I'd always do RAW adjustments anyhow.)

The reason why I mention this is that if one wanted to expose to the right, then using a white card to WB would be preferable over a gray card -- kill two birds with one stone. As far as whether one is a better WB than another, I really don't know.

The article is here: http://www.luminous-landscape.com/tu...se-right.shtml

!c

[engstrom]

For setting white balance either an 18% grey card or a white card will work equally well. However, my preference is to use the 18% grey card because you have to be sure and not blow out the white card or else you lose the ability to set the white balance.

[jeffkohn]

Anything neutral can be used as a white balance target. I'd say something in the 3/4 tone range (ie light gray) is probably ideal, simply because it will be easy to get a good exposure from. With a truly white card, you'd have to be a bit more careful not to overexpose it (and just becuase your three-channel camera histogram doesn't show any clipping doesn't guarantee that one or more colors are actually clipped a bit).

I find that for most of the stuff I shoot there's actually a bit of wiggle room in what works for a white balance setting. And often times, I prefer something other than 100% neutral WB anyway. So it's good to have a neutral starting point, but from there I often adjust to suit my taste and what I feel works for the image.

[texaskev]

Thanks all, I learned from this thread.

[Pikachu]

Originally Posted by shutterdrone

The reason why I mention this is that if one wanted to expose to the right, then using a white card to WB would be preferable over a gray card -- kill two birds with one stone. As far as whether one is a better WB than another, I really don't know.

The article is here: http://www.luminous-landscape.com/tu...se-right.shtml

!c

I would think using a whie card to meter exposure would have the opposite effect. The meter would try to set the white card's exposure to neutral grey, which would cause an underexposure. That would end up exposing to the left instead of the right. The same principle as, for example, when shooting a bright snow scene with in-camera metering you need to overexpose 1.5-2.5 stops to avoid rendering the snow as grey.

[shutterdrone]

Originally Posted by Pikachu

I would think using a whie card to meter exposure would have the opposite effect. The meter would try to set the white card's exposure to neutral grey, which would cause an underexposure. That would end up exposing to the left instead of the right. The same principle as, for example, when shooting a bright snow scene with in-camera metering you need to overexpose 1.5-2.5 stops to avoid rendering the snow as grey.

There might be some confusion here, I'm pretty sure that the comment I was referring to from Bruce Lindbloom in the article was to set the exposure, not necessarily automatically. As the article stated, you meter it, and then adjust the metered exposure until the brightest white (in your scene, or the white card) is just within clipping. That is, adjusting so that your histogram is more right-oriented than center-oriented. If there's no pure white in the scene, one should probably not meter off a pure white card, just as if the scene is really low-keyed (say all values in the first three zones), you probably wouldn't want to meter on an 18% gray card either -- but instead, meter on a 3rd zone value, and then bump up exposure until zone 3 became zone 8 or 9. Of course, reason follows that such an adjustment may not be possible without introducing other serious issues =)

!c

[engstrom]

Originally Posted by Pikachu

I would think using a whie card to meter exposure would have the opposite effect. The meter would try to set the white card's exposure to neutral grey, which would cause an underexposure. That would end up exposing to the left instead of the right. The same principle as, for example, when shooting a bright snow scene with in-camera metering you need to overexpose 1.5-2.5 stops to avoid rendering the snow as grey.

Depends on how much of the frame the card covered. If it was a white card that was just 5% of the frame then the rest of the frame could influence the exposure enough to blow out the white card.

[jeffkohn]

Originally Posted by shutterdrone

There might be some confusion here, I'm pretty sure that the comment I was referring to from Bruce Lindbloom in the article was to set the exposure, not necessarily automatically. As the article stated, you meter it, and then adjust the metered exposure until the brightest white (in your scene, or the white card) is just within clipping. That is, adjusting so that your histogram is more right-oriented than center-oriented. If there's no pure white in the scene, one should probably not meter off a pure white card, just as if the scene is really low-keyed (say all values in the first three zones), you probably wouldn't want to meter on an 18% gray card either -- but instead, meter on a 3rd zone value, and then bump up exposure until zone 3 became zone 8 or 9. Of course, reason follows that such an adjustment may not be possible without introducing other serious issues =)

!c

Seems to me if you're going to take this approach, you don't need an exposure target at all. Just meter off something in the scene. That's what I do. After a while you learn what objects will give you a good meter reading, and it become almost second nature.

[LEATHERNECK]

Originally Posted by jeffkohn

Seems to me if you're going to take this approach, you don't need an exposure target at all. Just meter off something in the scene. That's what I do. After a while you learn what objects will give you a good meter reading, and it become almost second nature.

Ditto !!!

[KeithAlanK]

I have found that for setting a custom white balance, it's a good idea to go with the recommendations from your camera's manufacturer, for your particular model.
Takes the guesswork out of it, and you don't have to wonder if you're following good advice, bad advice, or a method that works for someone else because their camera was designed for their method.

Call me crazy, but looking through the owner's manual is helpful sometimes.
If you have lost the manual, googling for 10 seconds will usually turn up an online version, usually in downloadable .pdf format.


My manual says to use a white target, so that's what I do.
1000 sensible arguments for grey won't sway me for this reason.

[Pikachu]

Originally Posted by engstrom

Depends on how much of the frame the card covered. If it was a white card that was just 5% of the frame then the rest of the frame could influence the exposure enough to blow out the white card.

Right, I get that, but the way I was reading it was using the shot to set exposure and white balance. To set a custom WB, you would have to fill the frame. With a full frame of white the shot will be underexposed.

[engstrom]

Originally Posted by Pikachu

Right, I get that, but the way I was reading it was using the shot to set exposure and white balance. To set a custom WB, you would have to fill the frame. With a full frame of white the shot will be underexposed.

Yes, that's correct. But if you're setting the exposure with the white card you'll have to bump up the exposure so that the card is white instead of the medium grey that the camera's meter would set it to.