[meteorite-list] Re: THE ART OF PHOTOGRAPHING Pictures 101

From: Martin H. <planetwhy_at_meteoritecentral.com>
Date: Sat May 21 16:30:12 2005
Message-ID: <20050521203010.83934.qmail_at_web40724.mail.yahoo.com>

Hi Sterling and all,

The 18 percent gray is more than trivia. The famous
photographer John Shaw describes the light meter as
actually a 'gray meter' and the implication are
important.

If you point a photographic light meter at snow in the
sun, and take a picture, you will get an 18 percent
gray picture. In order to make snow white, you have to
over-expose the image in order to washout the white to
actually make it white.

With a digital camera, one can use the white balance
adjustment to not only overcome issues of light
temperature (ie. incandesent v. florescent etc.) but
also adjust for a proper white in an exposure.

But there might be an easier way depending upon your
digital camera and that is with the scene selection
options. The camera many have settings that compensate
for backlighting, bright skys, bright foregrounds,
night shoots, etc. If you have a light colored
meteorite on a black background, it is similar to a
light colored ballet dancer on a dark stage. Or if you
have a darker specimen on as light background, it is
similar to a skier on bright white snow. Simply
setting playing with the scene selection choices and
understanding how the camera is reading the light may
make meteorite photography a whole lot easier.

But it is also like using a GPS telescope. You can get
great results, but you might not know how or why.

Happy clicking.

Martin--- "Sterling K. Webb" <kelly_at_bhil.com> wrote:

> Hi,
>
> Before the first days of auto-exposure
> calculation in cameras (film then), the
> problem has always been to sum all the lights and
> darks in a potentially infinite
> range of images to determine a single correct
> exposure. The original solution that
> underlies auto-exposure and all the sophistication
> of today's cameras is to assume
> that if all areas of the proposed image were mixed
> together like paint, the overall
> outcome would be an 18% gray.
> For decades, Kodak sold 18% gray cards and
> sheets for photographers to
> calibrate their exposures manually, even before
> "auto" exposure. Even though they
> may be using a $10,000 digital camera, most
> (probably all) professional
> photographers have yards and yards of 18% neutral
> gray backdrop material. 18% gray
> is the starting point for "correcting" exposure if
> needed. It will produce the best
> results, just like Anne said, for the reason that
> the underlying algorithms of the
> camera's electronics are build on that supposition.
>
>
> Sterling K. Webb
> -------------------------------------------------
> Impactika_at_aol.com wrote:
>
> > And I never use a black background, it just drowns
> out the specimens. I
> > found some file folders in a very soft, neutral
> shade of gray and I find that it
> > does not distort the color of whatever pieces you
> put on it, being a green
> > Tatahouine, a very dark Kainsaz or a yellow Libyan
> glass.
>
>
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Received on Sat 21 May 2005 04:30:10 PM PDT