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06-17-2013, 05:52 PM   #1
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grey card test

Im a photography student and on of my questions is to do a greycard test to build a zone ruler. I have done this multiple times and getting frustrated. Can or will anyone walk me through this? what is the best lighting for this? how do I get 13 shots for dynamic range using full stops? I dont want you to do my homework just simplify for me if you can or will.
Please and thank you
christy

06-17-2013, 06:52 PM   #2
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Set your grey card up, camera on tripod. Take exposures starting at 1/ISO @ f/22 and keep opening your aperture until you have your 13 exposures. Unless you have a fairly fast lens, you will have trouble getting a full 13 steps.

f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 is only ten steps, so you will have to adjust exposure to get the two end values.
06-17-2013, 06:57 PM   #3
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Hi Christy, welcome aboard. As you probably know, reflective meters such as the ones found in your camera are designed to average all the light values of a scene to a middle gray that is situated exactly half way between black and white. So when you spot meter off of a gray card, you're giving the camera exactly what it expects the scene to average out to. It's like those Staples commercials with the "easy button", this is the camera's equivalent, it can't miss the exposure.

So the first thing I would do is set up your gray card somewhere where the light isn't going to change. Indoors, away from windows is best, and try to find a spot that has even lighting, the center of the room is usually better than a dark corner. Then set your camera to aperture priority mode, and lock the ISO, don't let those two variable change throughout this exercise. With the camera pointed at the gray card, set your lens to the widest aperture it will support, doesn't matter what it is, it's just a wider aperture will keep your shutter speeds from going over 30 secs (hopefully), now adjust your ISO until the camera say that the correct shutter speed is between 1/60th and 1/125th. Take a shot of the gray card and note the shutter speed, this will be your Zone V value, the center of your gray scale.

Now put the camera in manual mode, and transfer all the settings that you just determined in Aperture priority mode, aperture, shutter speed and ISO. Now turn the shutter speed dial and observe the numbers. Every time you double of half the shutter speed, that's one stop. So if 1/60th was your "correct" exposure value, you'd want to take a shot at 1/30th, then 1/15th, then 1/8th, then 1/4th, then 1/2, and 1 sec. Don't worry about a little camera shake, it's just a gray card, not fine art. Then go the opposite direction 1/125th, then 1/250th. then 1/500th, 1/1000th, 1/2000th, and 1/4000th. This should give you a series of your middle value plus 6 shots above and 6 shots below.

Hope that helps.
06-17-2013, 11:34 PM   #4
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The camera will underexpose your greycard though with about half a stop but the greycard should be a nice consistent target and perfect for the job.

Here you can find a table with full stops, either move the aperture to these values or use the shutterspeed.
Exposure value - Wikipedia, the free encyclopedia

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