How to use a gray card

[mullsey]

Can anyone give some tips on using a gray card. I have a Canon 40d, I have been trying to take some product shots on a white back ground and they are coming out under exposed.

Any help would be great

 

[RockstarPhotography]

Can anyone give some tips on using a gray card. I have a Canon 40d, I have been trying to take some product shots on a white back ground and they are coming out under exposed.

Any help would be great

grey cards are used to set white balance. not exposure.

 

[SWFLA1]

Mullsey - Get your lighting and product completely set up, place the grey card in place of the product and meter the grey card. That should be your meter setting for your product.

Good Luck!

 

[SabrinaO]

Im curious too on how to use a gray card. Do you meter the gray card with or without the strobes you are gonna be using? Wont the flash alter the 18% gray color?

 

[Buckster]

Im curious too on how to use a gray card. Do you meter the gray card with or without the strobes you are gonna be using? Wont the flash alter the 18% gray color?

Meter with the strobes. Yes, they may indeed alter the color balance, and that's really the point.

The gray card is an anchor on equal values of the color wheel. If the strobes shift the color in some direction, we can bring it back to equal again because of the gray card, which we know should be equal, eliminating that color shift.

That's the white balance part of using a gray card.

The 18% (or 12%, depending on how persnickity you want to get) part of using a gray card is that's the standard anchor on a "normal" diffused value in terms of reflected light - which just happens to also be the standard anchor that light meters are tuned to (this is where the 12% comes in, which is half a stop lighter than 18%).

In any case, it works particularly well to get a proper diffused value of caucasion skin tones. If you're shooting portraits of caucasions, this will get you in the ballpark of a correct diffused exposure value for the skin, if not nail it. For lighter or darker skin, you may need to adjust accordingly - it's a starting point. For more extreme examples, if you're shooting snow or coal, you'll need a lot more compensation to nail the exposure and not lose details via over or under exposure.

So, it does both: white balance AND exposure balance, when used properly.

 

[RockstarPhotography]

Im curious too on how to use a gray card. Do you meter the gray card with or without the strobes you are gonna be using? Wont the flash alter the 18% gray color?

Meter with the strobes. Yes, they may indeed alter the color balance, and that's really the point.

The gray card is an anchor on equal values of the color wheel. If the strobes shift the color in some direction, we can bring it back to equal again because of the gray card, which we know should be equal, eliminating that color shift.

That's the white balance part of using a gray card.

The 18% (or 12%, depending on how persnickity you want to get) part of using a gray card is that's the standard anchor on a "normal" diffused value in terms of reflected light - which just happens to also be the standard anchor that light meters are tuned to (this is where the 12% comes in, which is half a stop lighter than 18%).

In any case, it works particularly well to get a proper diffused value of caucasion skin tones. If you're shooting portraits of caucasions, this will get you in the ballpark of a correct diffused exposure value for the skin, if not nail it. For lighter or darker skin, you may need to adjust accordingly - it's a starting point. For more extreme examples, if you're shooting snow or coal, you'll need a lot more compensation to nail the exposure and not lose details via over or under exposure.

So, it does both: white balance AND exposure balance, when used properly.

huh......i never heard of a grey card used for metering.....guess I learned something today, although I would still prefer to meter my subject.

 

[Buckster]

Im curious too on how to use a gray card. Do you meter the gray card with or without the strobes you are gonna be using? Wont the flash alter the 18% gray color?

Meter with the strobes. Yes, they may indeed alter the color balance, and that's really the point.

The gray card is an anchor on equal values of the color wheel. If the strobes shift the color in some direction, we can bring it back to equal again because of the gray card, which we know should be equal, eliminating that color shift.

That's the white balance part of using a gray card.

The 18% (or 12%, depending on how persnickity you want to get) part of using a gray card is that's the standard anchor on a "normal" diffused value in terms of reflected light - which just happens to also be the standard anchor that light meters are tuned to (this is where the 12% comes in, which is half a stop lighter than 18%).

In any case, it works particularly well to get a proper diffused value of caucasion skin tones. If you're shooting portraits of caucasions, this will get you in the ballpark of a correct diffused exposure value for the skin, if not nail it. For lighter or darker skin, you may need to adjust accordingly - it's a starting point. For more extreme examples, if you're shooting snow or coal, you'll need a lot more compensation to nail the exposure and not lose details via over or under exposure.

So, it does both: white balance AND exposure balance, when used properly.

huh......i never heard of a grey card used for metering.....guess I learned something today, although I would still prefer to meter my subject.

Yeah, and today's in-camera meters do a good job with that, so it's not much fuss. Still, since I'm usually setting up the lights and color balance and all with a gray card anyway before I park my subject in front of the lens, why not get the diffused value too while I'm at it?

If nothing else, it's nice to have the knowledge and ability to do so for the occasions where it comes in real handy. Corporate head shots come to mind. When you're already properly metered for both color balance and diffused value for portrait work, they walk in, you shoot, they're gone - no time wasted working on getting correct diffused skin values while Mr. Executive looks at his watch.

 

[Buckster]

Oh, and by the way, might as well mention this:

Some folks are familiar with the idea of metering off the palm of their hand to get exposure value. The reason why ties right in here: Because that and an 18% gray card give about the same diffused value, which ties into what I mentioned before about it being good for setting up for caucasion skin portraits. Pretty much everyone on the planet has "caucasion" palms.

Maybe that can help connect the dots, so to speak.

 

[Christie Photo]

huh......i never heard of a grey card used for metering.....guess I learned something today, although I would still prefer to meter my subject.

Yeah.... that's really what gray cards are for. It's only since the digital revolution that they're used for color balance.

Metering the subject is fine too, so long as your subject is fairly close in value to gray.

-Pete

 

[kundalini]

.... although I would still prefer to meter my subject.

Would that be reflective or incident metering?

 

[Christie Photo]

.... although I would still prefer to meter my subject.

Would that be reflective or incident metering?

GOOD question!

-Pete

 

[jritz]

.... although I would still prefer to meter my subject.

Would that be reflective or incident metering?

Probably incident because using a gray card would be reflective.