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

[Sterling K. Webb]

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.