gray card and metering mode

I have a question about using a grey card for exposure.

using a grey card, what type of meetering should i use? point meetering?
lets say i have a subject at 10 feet on a white background . should i just leave my camera in matrix meetering and set exposure with the gray card in the picture? how large should the gray card cover my view to get an accurate reading? same thing for white balance?

Any mode BUT matrix/evaluative (they are not based on any standard).

I covered gray card use here:

www.photographytalk.com/photography-arti...tipusing-a-gray-card

HTH

The card should cover the entire view (or most of it) if I read correctly. If you have a small one that can't do this, you can always have it centered and use spot metering. As to what metering you should use, it depends on what you're shooting. If you want to meter for only a certain part of an image, use center or spot metering, for an evenly exposed shot, I use evaluative metering.

Hi Matthew. Would you know a company that makes a product that has gray card on one side and a white balance card on the other side? It's a hassle to carry two cards.

lucky1one wrote: Hi Matthew. Would you know a company that makes a product that has gray card on one side and a white balance card on the other side? It's a hassle to carry two cards.

What is a white card used for?

TMR 001 wrote:

lucky1one wrote: Hi Matthew. Would you know a company that makes a product that has gray card on one side and a white balance card on the other side? It's a hassle to carry two cards.

What is a white card used for?

I imagine the OP wants the white side for white balance.

If the gray card fills the viewfinder it doesn't matter what mode you are in. If you can't fill the viewfinder you might use partial or spot metering. You can just hold the card up in the same light as the subject, and take a quick reading. Just make sure you aren't casting a shadow on the card.

I've been using evaluative metering for 5 or 6 years now. It seems just as consistent as any other reflective metering mode to me. Recently, reading Matthew's comments on evaluative metering mode, I've been metering various scenes using both center weighted and evaluative. I have yet to find one where the reading is different from mode to mode.

As long as the gray card is truly color neutral it would work fine for white balance. Tone doesn't matter.

HP, the way matrix/evaluative metering modes work is by comparing the tones (and now colors and distances with 3D matrix) in the scene to images stored in a database. It "picks" one it thinks matches best.

In my own experience, it is never consistent. My guess is it might pick one image for a reading and another for a second reading -- but I have no way of knowing. No one does.

I've taken Matrix metered pics in controlled lighting environments and gotten various results from the readings.

We know CWA (and spot/partial) are based on the same 18% standard that the gray cards are.

lucky, I sell a dual purpose card, and will be picking some up today. They are based on Robin Myers Imaging DGC-100 (a very accurate WB tool) and I have one side painted using Munsell N4.8 gray (18% reflectance) paint I had an artist mix for me.

There's been a glitch in production (my nephew was the painter and screwed up two batches) but I recently found a replacement. He's an award winning bike painter named Spider.

Let me know if you are interested. Hopefully, Spider's got it right this time.

Matthew

TMR you CAN white balance with ANY neutral colored object -- even cement. The most accurate tools are a light shade of grey. If white gets overexposed it doesn't give accurate results.

HTH

Thank you, Matthew. I'll keep that in mind. By the way, about how much do your cards go for?

I don't want more orders till I get the last ones filled. I'll know later today if Spider handled the painting well (or not). Seems getting an even skin of oil paint on PVC is trickier than it sounds.

When I go back to production level, I sell them for $24.95 with a bamboo lanyard.

Matthew

@ TMR

A white balance card is used to help you capture colors accurately. By accurately, I mean realistically. To accomplish that, your white balance camera setting must match the color temperature of the light source and condition you were in when you shot the picture.


Different light sources, conditions, and time of day have different temperatures. As such, they cast certain colors. For instance, if you take a picture lit by a household tungsten light bulb, the overall picture may come out orange. If you take a picture in the shade, the image may come out blue. If you take a picture under florescent lighting, your picture may come out green.

There are various ways to ensure you capture accurate colors:

-the easiest and most convenient way is to set your camera to automatic white balance. In majority of time, it works quite well. You let the camera set the white balance for you based on its own calculations. For most people, this method is good enough.

-another way to set white balance is matching the white balance icon in your camera to the lighting condition you're shooting in. For example, if you are shooting on a cloudy day, select the cloud icon in your white balance setting. If you are shooting under tungsten lights, select the light bulb icon in your setting. Remember that you have to change your icon each time the lighting situation changes.

-a third method is to use a white balance card to set custom white balance. You basically take a picture of the card and instruct the camera to set white balance based on that card. As in the previous example, it is important to set a new custom balance whenever the lighting situation changes. This method is more accurate than the others. This is particularly important when color accuracy is vital, such as when you are shooting products for clients.

You can also set the white balance in post production with Photoshop. Like before you first take a picture of the white balance card. (In this case, you don't need to set custom white balance on your camera while you are shooting.) In post production, select the picture in which your white balance card was shoot in. Using the eyedropper tool, click on the image of white balance card. Now, Photoshop will correct the colors based on the image of the white balance card. You can color correct images in batches.

I'm sure there are many other tools and ways to color balance your pictures, such as an Expodisc. When you are shooting with a flash, you can use color gels to correct colors.

Lastly, no one says your images must be color balanced. Sometimes you can use inaccurate colors for creative effects.

Well put lucky!

I want to emphasize the last point. Sometimes we DON'T want a true WB setting. We want to see the color of the light. It adds a mood to the image.

As a pro, you should KNOW what the color will be even before you shoot. And choose to use it (or not).

Matthew