To grey card or not?

[Harry Settle]

Everyone is swearing by using the 18% gray cards to set up white balance, so as soon as I decide to invest in one, I run into this website , http://luminous-landscape.com/tutorials/sharpness.shtml, that says it doesn't work that well with digital. Now I am really confused.

[Digital Prophet]

You know what? I too have seen articles to the effect. But let me tell ya. I got a grey card (not that I always use it) and I like it. You just have to be sure that you are taking the shot of the card in the same light as your subject. In other words, don't take the grey reading under a tree if your subject is in open light.

But you know, the real benefit of a grey card isn't that it is grey. It is that it reflects approximately 18% of the light that falls on it. To that end any surface that has the same approximate reflective quality will work. I read an article about this very matter. But I can't recall where.

Let me stew on it.

- Digital Prophet -

[Harry Settle]

I understand fully that it works that way with film cameras, have used a card for years in that venue, they are saying that digital cameras don't register the same way.

[Jon]

Could you post a little more to help me follow your link? It takes me to a "page not found" on the site. Might help cut through the fog.

[Jesper]

Leave off the comma after the URL: http://www.luminous-landscape.com/tutorials/sharpness.shtml

But that article is about sharpness, it doesn't mention anything about gray cards. A gray card works just as well with a digital camera as with a film camera.

Note that you can use a gray card for two completely different things: (1) to determine the correct white balance, (2) to determine the correct exposure.

[Harry Settle]

Sorry, I copied the wrong link from the "favorite links" thread. Try this one, way down at the very end. http://www.luminous-landscape.com/tutorials/expose-right.shtml

[psk4363]

Harry,

Just a thought - :?: why not use an incident light meter instead :?:

Cheers,
Barry

[DaveG]

Everyone is swearing by using the 18% gray cards to set up white balance, so as soon as I decide to invest in one, I run into this website , http://luminous-landscape.com/tutorials/sharpness.shtml, that says it doesn't work that well with digital. Now I am really confused.

All I know is this:

Since I started to use a grey patch (this is a grey scale rather than just one 18% grey card) in Photoshop my colours have been 100% better. Now the following is only going to work if you are doing a bunch of shots under the same lighting conditions - or you're willing to include the grey scale in every shot.

I take the shot of the subject holding the scale and use the colour sampler tool to sample the highlight grey, midtone grey and a shadow grey. Then I go into layers and make an adjustment layer/colour balance. When that comes up I go by the numbers and zero the highlights, then midtones and then shadows, with the sliders. If all the number are the same then I CAN'T have any colour cast in the shadows, midtones or highlights! Now it's almost impossible to get all three sets of numbers to match exactly since when you change the shadows there may be some change in the midtones. But one or two numbers off is of no concern.

After I get this sample image neutralized, I open up the first "real" file. Then I put my cursor on on the adjustment layer and drag it onto the new shot. That adjusted layer sits on top of my real image and provides the same colour correction as on the sample image.

When I couple this with using the histogram to make sure that the exposure has no shadow or highlight clipping I end up with a digital negative that's based on instruments, not the seat of the pants flying like I did before.

This takes the monitor out of the equation too. I have a Spyder for calibrating my monitor screen, but I also have no confidence in how well this actually works. But I figure that if I use Adobe RGB, have a very well exposed and processed capture, and my colours are all neutral then surely a lab can make a very good print. And so far they have!

[mjordan]

You don't set white balance with film. :lol: You can use a MacBeth chart or other calibrated charts in a picture on the roll so that a human printer at a custom lab can use it to adjust color balance when the images are printed, or if you digitize the images and bring it into Photoshop or some other image editor. But you don't set the white balance in a film camera... at least mine don't have that feature. :wink:


As for setting the white balance in a digital camera, some work best with gray, some with white. Some work best with light gray and some with 18% gray. It depends on the sensor of the camera and one of those details that each person should test with their equipment and their work flow on how they like their white balance to look. This is another area that one answer does not fit all situations. For most people, gray or white is probably going to get you so close that you won't know the difference, nor will your customes if you are shooting for others.

Mike

[Harry Settle]

I'm anxious to try things out, when I get the cards, and make decisions from there. Thanks for the input all.

[Jesper]

Sorry, I copied the wrong link from the "favorite links" thread. Try this one, way down at the very end. http://www.luminous-landscape.com/tutorials/expose-right.shtml

Ok, but this article is about getting the exposure right.
White balance and exposure are not the same thing.

[Aylwin]

As Jesper has mentioned, the gray card can be used for exposure or white balance. If I remember correctly, using a gray card to determine correct exposure doesn't work (or at least not very well) with digital. However, it works great for calibrating white balance.

I can't remember where I read this though so I'll have to look it up... :roll:

[DaveG]

As Jesper has mentioned, the gray card can be used for exposure or white balance. If I remember correctly, using a gray card to determine correct exposure doesn't work (or at least not very well) with digital. However, it works great for calibrating white balance.

I can't remember where I read this though so I'll have to look it up... :roll:

A grey card should be wonderful for correcting exposure. It isn't though, and the problem comes in two parts. The grey card is 18% grey and my understanding is that the reflective meters in current cameras don't use 18% grey as a base any more. I have no idea whether it's something like 14% or 22% but it doesn't seem to be 18%.

The other thing is the camera's ISO. I use a Minolta Autometer IVf flashmeter for determining lighting ratios with studio strobes. When I used film cameras with slide film, I would meter each flash to get the ratio right and then meter the combined output to get my base exposure, since the slide film's latitude wold not tolerate the over exposure.

With my 10D I find if I do this then my exposures are about 2/3 of a stop overexposed. As a quick and dirty fix I set the ISO on my meter at 160 now (instead of 100) and this works just fine. A friend at another studio has been doing the same thing with his drebel, so it doesn't sound like my meter is at issue.

[Harry Settle]

Ok, I'm awake now. I don't know what I was thinking. I knew that the purpose of the grey card was for "exposure" not white balance. I got confused in reading so many exposure, whitebalance threads and tutorials lately, that I slipped a gear. Take me out behind the shed and whoop me.

In video, we use "warm cards" to set white balance in different situations. After reading through the Canon manual about setting a custom wb setting, along with the last post here, It became very clear that I had my head, and shoulders, up my . . .

Thanks for putting me straight.

[Headcase650]

Ive read on some other sites that a coffe filter or a plastic pringles lid works perfectly for setting the white ballance on the 300d and the 10d.