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Photography Question 
Kix  Pix

Of Gray Cards and Spot Metering

When using a grey card - provided I have a built-in spot meter - do I spot meter the grey card then recompose? All the while keeping the spot meter button held down? Should you bracket any time with a grey card? It's just not easy holding these buttons down while you're composing, focusing, etc. Also, if I were to select from my honeycomb pattern a different area of focus, would this not eliminate the need for a grey card? Thanks for your help.

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5/7/2004 5:33:19 PM

Terry L. Long   I'm not sure what camera you've got, and I'm a little confused by what you mean by "keeping the spot meter button held down." I'll give it try, though. With my 35mm system, I use my spot meter 99% of the time. Also, if possible, I use my 18% grey card. Here's what I do: Using a tripod (99.999...% of the time), I compose my scene. If I'm standing in the same lighting as my scene I'll hold my card in front of the lens and meter the card. I then set my meter to read correctly. At this point, I'm finished metering and I've already got the scene composed, so I take the shot. Also, since I use transparency film, I'll bracket in 1/3 stops in either direction. With my digital camera, which doesn't have a spot meter, I do the same steps as above - but I hold the card close enough to fill the entire frame. So, it doesn't matter what type of metering is set on the camera, it'll just read the card and act as if I'm using a spot meter. I follow the same steps after that point. I have a "kicker" for you, though: My card isn't grey ... it's 18% green (or medium green). The reason I use green is because I mainly shoot scenics, which usually have green in them. So, if I'm not standing in the same lighting as the scene (shadows), then I look for some green in the scene that pretty well matches the green card. Then I spot meter that area and set my meter accordingly.

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5/7/2004 10:29:46 PM

Bob Cammarata
BetterPhoto Member Since: 7/17/2003
  By "keeping to spot metering button held down", while re-composing, it appears that you are attempting to use the auto-exposure capabilities of your camera ... along with the gray card. I can see how this would be a bit cumbersome. Try setting the exposure system to full manual (if your camera has this function), and follow the advice Terry offered to meter the card and set the exposure. The benefit of using a gray card is that it allows you to get an average of all the reflected light values within the scene. As mentioned earlier, the light hitting the card MUST be the same as the scene you are shooting.

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5/8/2004 1:13:01 AM

Peter K. Burian
BetterPhoto Member Since: 4/8/2004
  James: My two cents worth. Yes, you can spot meter the card - in the same light as your most important subject. Then, hold the AE Lock button while you recompose so the exposure settings do not change. Or use the camera's Manual mode. Spot meter and adjust aperture/shutter speed until the metering indicator shows that you will get a correct exposure for the gray card. The only advantage is, you can then keep shooting at those same settings without holding a button.

Note: Ignore any warning of incorrect exposure when you recompose. The exposure will be correct for the card and that is what you want.

The most effective way is this - using Manual mode. Set the card up in the scene at the distance that you want to focus. Take the meter reading, make the correct aperture and shutter speed settings. Put the camera down, remove the gray card from the scene. Shoot all the images that you want - as long as the light does not change.

You can do the same with Honeycomb pattern metering. But if you fill the frame with the gray card, the exposure should be the same as with spot metering.

Also, your question: "If I were to select from my Honeycomb pattern a different area of focus, would this not eliminate the need for a grey card?" My answer: No. If you are absolutely insistent on the most accurate exposure, use the gray card instead. And yes, when using the card, bracket in 0.5 step increments to be absolutely sure of a perfect exposure. Personally, I would just use Honeycomb metering, and set AE Bracketing and forget about the gray card. This meter is quite reliable. Cheers!

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5/9/2004 7:54:00 AM

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