Grey Card Help Please :).

[michillebaker]

Hello Everyone,

Ok, I just recently over the past couple months have been using great cards. I don't know if I am not angling it right or not setting it correctly on my camera but I can't seem to get my photo's to look right when I use my grey card. I always have to fix the color in photoshop after words. I have also noticed that when I have to bring my 430ex II flash exposure up the colors start to shift and they really don't look correct.

I would like to know these things.

1. Do i every time I changed my flash exposure have to reshoot the grey card and set my white balance again?

2. Should the grey card be slanted?

3. Does the card have to fill the frame and maybe that's what I am doing wrong?

Here is a photo I took recently of my daughters. The first photo is the one with the grey card. After shooting the grey card i went into my camera's setting and changed it to custom white balance and then I clicked on this photo.

1.

http://farm4.static.flickr.com/3212/3133419374_9b983b78f5.jpg

2. This photo was taken 5 pictures after the grey card reading! I did nothing to this photo. You see what I seen right out of the camera.

http://farm4.static.flickr.com/3136/3132597929_e8ac5dc9e3.jpg


Anyhelp would be so apreciated. Also everyone have happy holidays!

Michille

[SkipD]

The second shot appears to be a little underexposed relative to the first (which may have been slightly overexposed), and that tends to make the colors a little richer. That, in turn, makes it easier to see what appears to be differences in the tones.

[bobbyz]

Hello Everyone,
1. Do i every time I changed my flash exposure have to reshoot the grey card and set my white balance again?


Yes.


2. Should the grey card be slanted?


I keep it so it is flat facing the camera.


3. Does the card have to fill the frame and maybe that's what I am doing wrong?


Only if you doing custom WB inside the camera where you take a test shot and tell the camera to use it for WB. Even then I think yiu only need to fill the center circle not the full frame, unless somebody correct me?

[FZ1dave]

I was under the impression you need to fill the frame for a gray/white card exposure, at least that's the way I do it. It shouldn't be in focus either from what I gather.

I could be wrong on both counts though.

[michillebaker]

Well that stinks that every time I change my exposure i have to re-shoot the grey card and also reset the white balance. Also i did not know about that the grey card should not be in focus I always thought it did. I guess i have some more learning to do about grey cards.

Thanks,

Michille

[jeromego]

I was under the impression you need to fill the frame for a gray/white card exposure, at least that's the way I do it. It shouldn't be in focus either from what I gather.

I could be wrong on both counts though.
idont thinkyou have to fill the whole frame with canon. i know you have to with nikons.

[Curtis N]

1. Do i every time I changed my flash exposure have to reshoot the grey card and set my white balance again?The color temperature of a flash unit changes slightly with the power setting but it's usually not noticeable. However, in the shots you posted, you seem to have a combination of flash and ambient light. With two light sources of different color temperatures, changing the ratio of the two will change the white balance of the image. It will also affect different parts of the image to different degrees.2. Should the grey card be slanted?A slight angle to avoid a direct reflection of the light source is usually a good idea.3. Does the card have to fill the frame and maybe that's what I am doing wrong?If you're setting a custom white balance in the camera, follow the procedure in your camera's instruction manual. Generally the neutral reference only needs to fill the partial metering circle. If you're shooting RAW, just a small area in the image will suffice for use of the eyedropper tool in RAW conversion software.

Keep in mind that traditional gray cards are designed for exposure, not color. For white balance, I favor these two:

WhiBal card:
http://www.rawworkflow.com/whibal/

Ed Pierce calibration target:
http://www.photovisionvideo.com/stor...egory_Code=DCT

finally, understand that the "correct" white balance is not always the best white balance. I often raise the color temp a few hundred K with RAW conversion software.

[michillebaker]

You know, I just may do a test when I get home from work with regards to gray cards. I know when I first started learning about Grey cards I thought I was suppose to fill the frame and noticed a big improvement when I did, but recently i have been doing it the other way and only filling part of the frame. I just purchased this past month an external 430ex II flash and thought the whole time that this was the reason behind my color being off when shooting with a grey card but I am beginning to wonder if that is the actual issue. Anyways thanks for everyone's help.

Michille

[sfaust]

1. Do i every time I changed my flash exposure have to reshoot the grey card and set my white balance again?

Generally, no. If you made drastic changes to your lighting setup, then you would need to reshoot the grey card and readjust your exposure and color balance. But if you are simply moving the same lights around, adding lights of similar color temperature, or just increasing or decreasing the exposure, it won't change the color balance enough to make a difference. There will be very slight color shifts, but not enough to warrant re-setting the custom white balance.

If your lighting is mixed, say mostly from a small flash, but some room light or light from an open window, then adjusting your flash or exposure will indeed change the color temperature. Since you would be adding or removing one light source in relation to the other, and they are both vastly different in terms of color temperature, you are in fact mixing the two to come up with something in-between. A change in exposure could easily make a large shift in color temperature.

I.e., if your two lights are both flashes at 5600K, then adjusting the exposure of one or the other won't change the overall color balance. But, if one light is a flash at 5600K, and the other a tungsten household blub at 3450K, the actual color temperature is a mix of the two, say 4900K. If you adjust the flash stronger, the color could easily shift to 5100K and create a blue case in the image.

If you don't want to constantly make those changes, make sure all your lighting is from the same source. If you are using a studio lighting setup, or a few small flashes, make sure there is no other room light, window light, etc, that is part of the exposure. If the room lights are 5 stops or more lower than the exposure you are shooting at, it won't have any effect in the color balance.

[Milamu'g]

The grey card your using in the first photo is merely to get a proper exposure, has little to do with WB.

[sfaust]

The grey card your using in the first photo is merely to get a proper exposure, has little to do with WB.

Pros use grey cards for white balance all the time. I know I do. Its the same as a white, with the exception of being a few stops less in exposure. But if it is a neutral grey card, which most sold for photographic purposes are, they have equal RGB values and thus appear 'neutral white' to the camera.

Why double your work load shooting white and grey, when you can do both with a single grey card.

[D_CeLiRaToR]

i use the ghetto coffee filter method for custom white balance. cheap and it works!

[michillebaker]

How does the coffee filter method work?

[Curtis N]

How does the coffee filter method work?You put a coffee filter over the lens, put the camera in the subject's position and aim it at the light source. This is hard to do when the light source is on the camera's hotshoe.

There was a recent thread discussing the disadvantages and limitations of this method, and its more expensive version, the Expodisc.
http://photography-on-the.net/forum/showthread.php?t=617287