custom white balance plight

[debejyo]

Hi Guys,

 

I use a D40 and often face the following problem when trying to measure white balance using a gray card. Under

certain conditions, the camera is unable to gather the white balance data. It works sometimes and it does not,

quite whimsically. Does anyone know whats going on out here? It becomes annoying at times as there is no

provision of setting the actual temperature in this camera.

 

Thanks for your response.

[errol young]

I had same problem with my D70 and found that it needed a certain minimum light level to get a lock.

When WB is completely screwed up I have use B&W as a product.

[errol young]

One more thought. You could shoot raw and include a gray card then correct in Camera Raw or PS.

[debejyo]

Thanks for your comments, but I am not sure what you meant by "use B&W as a product".

[richard_driscoll]

I have a D40 and like Errol only have a problem when the light level is very low. I suspect that these low light levels are probably at the bottom end of the claimed metering range anyway.

 

You can't set the Kelvin degrees explicitly but you can trim the white balance on each of the preset settings. The instruction booklet tells you the Kelvin degrees corresponding to each of these trim values. Each trim step gives a shift of about 10 mired except for the fluorescent setting where the steps are wider.

[lex_jenkins]

Use a white card for white balance. The gray card is for metering, not white balance.

 

Gray is seldom truly neutral gray because it's a mixture of various colors. The purpose of a gray card is to provide a calibrated baseline for metering using reflected metering (usually spot metering). It's not intended for color balance. While the human eye has trouble discerning non-neutral grays, most of us can readily spot color shifts in "white".

 

BTW, this is not unique to the digital still photography era. We faced the same challenges decades ago when white balancing video cameras. We used white cards, not gray.

 

There are other complications involved in using gray cards for white balancing. Search the Nikon Forum archives using the search option on the upper left corner. Enter the phrase "white balance" in the box and choose a time frame to narrow the search results. You'll find some solid, accurate information along with the well-meaning but misinformed recommendations to use a gray card.

[debejyo]

Thanks Lex. Just to make sure I'm looking at the right product, is this what a white card is:

http://www.bhphotovideo.com/c/product/300868-REG/Porta_Brace_WBC_White_Balance_Card.html

 

Frankly, I did not know you get white cards - is it not prone to get dirty and yellow easily?

Thanks.

[lex_jenkins]

The customer reviews for that particular product are favorable, so it appears to be durable and can be wiped clean if necessary. The price is certainly reasonable.

 

In a pinch I've used an ordinary sheet of white paper. It virtually always helps get an accurate WB better than my gray card, which is useful only for metering. In fact, I don't even bother carrying my Kodak gray card anymore in my digital camera bag. I use it only with my medium format film camera and Pentax spot meter.

[richard_driscoll]

Lex,

 

Did Errol mean include a grey card in the shot using raw so that one can balance the colour in PP using the card as a reference?

 

I just use a piece of white paper to set the white balance in camera, grey would just waste light and as you imply risk a shift in colour balance. Some people mention use of the Expodisc or similar which fits over the lens. I guess a piece of opal plastic would be as good.

[debejyo]

Richard,

Talking about low light, believe it or not, I have measured moonlight white balance on a full-moon night using the gray card and it worked. I think its something more than low light. I had to open the shutter for 20s @ ISO 3200 but it did fine.

[cmulcahy]

Nikon's manual actually says to use a white card OR grey card to custom set your white balance on a D300.

 

Does it matter what model your camera is?

[richard_driscoll]

Dabejyo,

 

Could it be that the light is of a colour too far away from the range 2700-9000 Kelvin approx. ? Or might it have an abnormal amount of green mixed in too? Other than that I'm baffled.

[lex_jenkins]

If you can find a perfectly neutral gray card, absolutely neutral and free of any tint and without any halftone effect that can produce interference patterns, go for it. Most gray cards designed for metering purposes don't meet this standard.

 

It's easier and more accurate to use a white card.

 

If you got satisfactory white balance using a gray card under moonlight with a 20 second exposure at ISO 3200... that's serendipity at best. I wouldn't count on being able to reproduce that too often.

 

Unless you absolutely need to shoot directly to JPEG format and must get the WB correct in the camera, why not just shoot raw and do it the easy way in editing? I'm not sure I see the advantage to reproducing all the difficulties of using film while dispensing with the advantages of digital. And I'm talking from the perspective of someone who has spent many long, cold hours in the dark using all kinds of color negative and slide films in pursuit of long exposure perfection. Why fight the technological advantages of shooting raw? And why long exposures at high ISOs?

[debejyo]

Hi Richard,

There was no strong cast, it was a fine sunset evening. So, I'll leave you baffled here :)

 

To Lex:

I agree that it could have been serendipity. I just took a chance for the heck of it and it worked. Well, I don't

shoot long exposures at high exposure unless the sky is unclear and the stars are faint. For all long exposure, I

shoot raw but I like to get the white balance right so that the channels dont get too less or too much light, out

of proportion (since I don't have uni-white balance picture to use on D40).

 

I'll surely go for your white paper thing. I have used white paper before and they worked good. I guess I'm

trying to rely on the gray card too much, which I'll stop doing.

 

Call it a fantasy, but I like measuring the white balance and don't feel very happy if the camera denies it.

 

Thanks for your help. It was good to hear from all of you.

 

 

PS: just attaching my moonlight white balance picture (thought I processed it in raw ultimately :))<div></div>

[debejyo]

By the way, by high exposure in my previous post, I meant high ISO. sorry for the typo.

[gaute_solheim1]

If the "certain conditions" are sports halls or similar lighting, the problem may be that many modern lighting systems use a two source system for the light, with a big gap between the colour temperatures. The camera observes two distinct temperatures, and is not able to calculate the correct temperature to use.

 

It would be a good idea if someone made plug in filters for PS for each of the most commonly used two source lighting systems. I have some pictures were the white is white and the skin tones are excellent, but the colours of the team have transformed from a strong green to a purple/bluish kind of thing.