Grey Card

I have read how to use a grey card, but how close, or far away do you actually use it from the lens. I would like to know from actual users of the card. Thanks, Stephen.

I use them as much as possible and have read, seen and had success when the card takes up most, but not all of the picture. All the top pros I've heard from say that you should expose part of the background so you get more of the light you are metering.

If you are using it for custom white balance in the camera, then follow the instructions in the manual.

If you are including it in the shot so you can use white balance eye dropper in post processing it can be much smaller, but I would still do a separate shot with the gray card just for insurance.

I presume you are using a digital gray card that is neutral, rather than a photographic gray card that is intended as a reflective light metering aid and may be way off for white balance.

dmward wrote in post #12469129
If you are using it for custom white balance in the camera, then follow the instructions in the manual.

If you are including it in the shot so you can use white balance eye dropper in post processing it can be much smaller, but I would still do a separate shot with the gray card just for insurance.

I presume you are using a digital gray card that is neutral, rather than a photographic gray card that is intended as a reflective light metering aid and may be way off for white balance.

Where does one obtain this "digital" gray card? Never heard of it.
Thanks in advance for expanding my knowledge base.

Lightbender57

Hi Stephen,

The gray card is placed or held at subject position and in the exact light that falls on (and bounces off) your subject when you're shooting. Distance from the lens doesn't matter. Correct exposure absolutely matters.

If you're using the gray card to set an in-camera custom white balance then you want to either fill the frame or at least fill a large central portion of the frame. If you're using the gray card as a reference to be used in post production then you don't need to worry about the size of the card in the frame but you do still have to make sure it's properly exposed and in the same light as the subject.

Some (but not all) cards are neutral (equal values of R-G-B) and can be used for White Balance.

Some (but not all) gray cards are 18% gray and usable for setting Exposure.

Some (but not all) gray cards are useful for both White Balance and Exposure.

I think the reference to 'digital gray card' is regarding White Balance, but white balance is something important even to film, too.

If you are using something neutral to set Custom White Balance in camera, filling the frame is best. If you are using something neutral to set White Balance in postprocessing, filling the frame is not necessary at all.

Wilt said it.
Its gotten to the point that the term "gray card" if unreliable.

The irony is that Kodak Gray Cards used with film eons ago were 18% and used for reflective light meter readings. Essentially a substitute for incident meter reading. And, the meters were designed to read a 12% gray as proper exposure.

Now, it seems every manufacturer has its own interpretation of what makes the "best" gray/white balance reference.

All the observations made here are reiterating the need to know what you have and then determine how to use it effectively.

I downloaded a "Grey Kard" app for the iPhone and iPad but I'm skeptical of how to use it.
It seems like it would be unreliable for both metering and white balance, since the device gives off its own light instead of solely reflecting the ambient light.

Thoughts?

nathancarter wrote in post #12476629
I downloaded a "Grey Kard" app for the iPhone and iPad but I'm skeptical of how to use it.
It seems like it would be unreliable for both metering and white balance, since the device gives off its own light instead of solely reflecting the ambient light.

Thoughts?

Fun toy. Bad idea.

TMR Design wrote in post #12476636
Fun toy. Bad idea.

That's kinda what I thought.
There are some cool tools for the iPhone and iPad - "Simple DOF," which is a (you guessed it) DOF calculator; "Expositor," which is a slide-rule to help you determine correct exposure settings for a huge number of different lighting settings, a slate if you're doing video, even a digital model release form.

But I don't think the grey card is something that can be replicated in an electronic format.

TMR Design wrote in post #12469183
Hi Stephen,

The gray card is placed or held at subject position and in the exact light that falls on (and bounces off) your subject when you're shooting. Distance from the lens doesn't matter. Correct exposure absolutely matters.

If you're using the gray card to set an in-camera custom white balance then you want to either fill the frame or at least fill a large central portion of the frame. If you're using the gray card as a reference to be used in post production then you don't need to worry about the size of the card in the frame but you do still have to make sure it's properly exposed and in the same light as the subject.

what he said.

Thanks everyone for your thoughts and ideas. After considering all the info, I'm going with TMR Design and give it a try. Again thanks to all....this is a great forum to get real user help and ideas. Stephen.