Color balance and exposer set with greaycard

[jlw82]

What is the difference bewteen a color balance greycard and a grey card that is a for setting exposure?

[jimsolt]

What is the difference bewteen a color balance greycard and a grey card that is a for setting exposure?
I assume you mean "white balance" when you say color balance.

The difference is they are two different things and you set them by two different methods. The only thing the same is the gray card.

Use it to set a custom white balance if you wish to do that. Follow your camera's instructions. Different cameras do it differently. You can if you wish use a white card for this. You can also include the gray card in a RAW scene and use it to set white balance in the RAW converter.

Use it to meter exposure for a "medium" scene if you wish to do that. It will not measure exteme highlights or shadows. It will give you a reasonably accurate "medium" exposure.

I have a gray card and the instructions for use are printed on the back.

Most importantly DO NOT confuse the two measurements. They are not one and the same.

Jim

[DavidW]

You're after different properties from the card for the two tasks.

For exposure, you're after 18% reflectivity.

For white balance, you're really after something that's spectrally neutral to give you an accurate reference, even if you then decide to depart from that reference.. I use a WhiBal Pocket. Whether or not you want to buy the product, there's a lot of good information in the WhiBal Online Video User's Guide (http://pictureflow.fileburst.com/_Tutorials/WhiBal/index.html).



David

[SkipD]

What is the difference bewteen a color balance greycard and a grey card that is a for setting exposure?There is absolutely no difference in the grey card that you would use for both functions. As stated above, though, you use different procedures to measure exposure with a grey card or to set the camera's white balance setting with a grey card.

Some grey cards, such as the full-sized Kodak cards that I have come with a white on the reverse side that can be useful too.

[jlw82]

So.... The whitbal, in this case can both be used for white balance and set a neutral exposer?

[DavidW]

WhiBal isn't recommended for exposure - the reflectivity isn't guaranteed to be any particular value. The product is guaranteed to be spectrally neutral. Watch the first couple of videos on in the user guide - I found them very informative.



David

[jimsolt]

Watch the first couple of videos on in the user guide - I found them very informative. David
THAT is excellent advice. They are clearly selling a product, but they offer a lot of really good information useful whether or not you buy their product.

Jim

[jlw82]

Hmm, I may be stupid. But what is the difference between a neutral card and ha 18% reflective card. ;-)

[SkipD]

Hmm, I may be stupid. But what is the difference between a neutral card and ha 18% reflective card."Neutral" (as applied to colors) is used to describe the "non-color" of a surface. The "standard" 18% grey card is a neutral grey. In other words, all colors are at equal levels in the grey. The back side of a Kodak 18% grey card usually has a 90% reflectance white card which is also neutral as far as the color is concerned. It just reflects a lot more of the light that hits it compared to the grey side.

Either side of the Kodak card could be used for a white balance reference when setting custom white balance in the camera.

Only the 18% grey side works (without compensation) for metering a typical scene with a reflected light meter and the grey card.

[jimsolt]

Hmm, I may be stupid. But what is the difference between a neutral card and ha 18% reflective card. ;-)
The wiseacre answer is reflectance. It also is probably the right answer. I will quote from what is written on the back of my gray card:

"The Gray Card is specifically manufactured for the photographer and printer to aid in determining exposure, lighting ratios, and color balance. The Gray Card is manufactured to be neutral gray on one side. The gray side is designed to reflect 18% of the light hitting it."

This card was designed for film use "for perfect prints, negatives, & slides," but it is still usable for digital photography. Certainly the principles remain the same though technology has offered other techniques.

Jim

[Merle]

I like the digital calibration target as this allows me to check my histogram in white, black and 18 % gray in the same histogram reading.
http://www.photovisionvideo.com/ (http://www.photovisionvideo.com/)

When I'm on the fly, like I need to white balance for a wedding ceremony where I have not had the opportunity to use my calibration target, I use my EXpodisc with great results.
http://www.expoimaging.net/ (http://www.expoimaging.net/)

I like the confidence of being able to check all three tonal qualities in my histogram, with the calibration target. If I continue to get great results from the expodisc I may go to it exclusively, because of the ease of use, and the less amount of time required for CWB. ;) :) :D

Good shooting to ya !!
Merle