Quote:
Originally Posted by PhotoDave1
With deference and respect to Mr. Smith and the other learned members participating in this Thread I have to take exception to one comment in this Thread concerning Histograms.
From my somewhat limited knowledge a proper Histogram is an indicated of a properly exposed image and there is really no need to photograph a Gray Card or a White Card or any other card for that matter in order to get a good Histogram and therefore a good image.
I try whenever possible to photograph on Manual and I was doing this last weekend during a shoot with a very popular model when I dropped my light meter and went into a state of utter panic. I didn't want to end the shoot because it might have been a month or more before we could re-schedule and I didn't want to "guess" at my exposures because the light was changing rapidly and I didn't want to photograph on "Program" mode so I had the idea to bracket a couple of exposures using my light meter as a center point and the Histogram function of my camera as confirmation.
Once I had adjusted my meter to give me a good Histogram I was once again set to go and this was confirmed when I uploaded my images into my computer and view them in Photoshop. The Histograms were spot on.
Please note that this was my experience and may not be representative of your results and then of course there is the possibility that it was just plain dumb luck on my part but it worked and save my shoot. Nuff said!
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The purpose of photographing a gray card, or a black/gray/white card, is simple. It allows one to see a histogram that is exactly predictable. In other words we know exactly what it should look like if the exposure is correct. This is not always the case with other non-uniform objects. For example, a well exposed image of a 18% gray card will always have one spike right in the middle. I usually shoot in manual mode also and I generally use either a gray card or the B/G/W target. It normally takes just one shot and one look at the histogram to get me to the correct exposure. But you can also do something similar with faces of people. The problem with your method (as you explained it) is with the phrase "good histogram". That phrase doesn't really mean much by itself. It should be a "good histogram" of some particular thing or object. I mentioned a "good histogram" of a gray card. We know what that should look like an it will look the same to all of us. With experience one can look at a histogram and know if the exposure is good. But that means we have to examine many hundreds of histograms of all sorts of scenes before we have the experience to tell just from looking. On the other hand anyone can tell if the histogram of a gray card shot has a good exposure.
One experiment that is very helpful with histograms is to take a photo and move it into photoshop and then grab the oval selection tool and make a selection of a small oval area of the photo. Look at the histogram of the selection. Then move the selection around the photo looking at how the histogram changes with each move. Compare each histogram of a small area to the histogram of the whole photo.
In summary you can judge exposure from the histogram and with experience can do it with any photograph. But you can gain greater precision with less experience just by using a gray card.
Cheers,
rfs