At 02:56 PM 9/5/2003, Les wrote:
>I read somewhere -- can't remember where at the moment -- that if one
>creates a histogram by taking readings from neutral gray, pure white and
>pure black, the display will show three peaks. You can then see at a
>glance whether exposure is correct, and whether you have captured the
>tonal range you aimed for. Have you tried this method?
Les, I just saw a reference to the white-black-gray card in an article
in the October 2003 Shutterbug magazine, p87. He says the technique is
credited to Frank Criccio. This was in an article of tips for setting
up studio lighting. The technique as you say uses white, black and gray
cards, where you get three spikes in the histogram. Adjust the exposure
so the spikes are not off to one side or the other.
Most of the photography I do is not studio, where the use of gray cards
is not practical, but the idea is to adjust the white and black points
of the histogram, something I do a lot in photoshop. Just looking at
the histogram of the scene itself, without the cards, one can set the
white and the black points by adjusting exposure. Also, spikes or peaks
in the histogram indicate areas of more constant tonality - one can
look at them in the scene and decide what tonality they should be. A
histogram can help over a spot meter when that tonality is distributed
in the scene.
So using the C-5050 as a light meter has an advantage through the
histogram feature and what that can tell you about possible exposures.
I used the histogram to adjust exposure with the C-5050 in this shot.
http://www.zuik.net/om/P9052094rd.jpg
It is only a fence gate latch I wanted to remember while shopping for
fences. The metering idea is that you can get spikes in the histogram
for a tonality you want to control but are not be able to spot meter.
The latch was black against a bright background. I was only interested
in the details of the black latch. I looked at the histogram display
and adjusted the compensation to bring the black peak in the histogram
to the center (I made black gray with +2 stops compensation). I didn't
want the bright background to influence the meter. Without the
adjustment, the black gate was clipping at the bottom of the histogram.
If I were metering for a film camera, the shot taken with the C-5050
will have all the exposure information stored for me in the metadata.
OK, so I'm trying to justify my digital toy. I'm sure any good
photographer would figure out how take a similar photo with just their
OM. I certainly would not waste film on a picture like this one though.
Wayne
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