Hi There was a recent comment regarding the effect on a faceted
stone of a setting that permits light to come in from the back. Out
of curiosity, I put a ring under a microscope and photographed the
stone with lighting from the front, the back and from both front and
back. I could see no real difference with the back lighting. You can
see the results at
http://www.sgams.org/Stones/Photography.htm
The stone in the picture is a color-change garnet. I wanted to
photograph the change, and I got a surprise. The color change is from
reddish to greenish. Under daylight, I saw the green of the stone.
But when I photographed it, the picture showed the red of the stone.
I had to use a graphics program to modify the picture to show what I
saw. You can see the pictures at the same spot as indicated above.
Does anyone have any comments about the accuracy of photographs of
color-change stones under incandescent lighting, an Ott (“natural”
daylight) lamp, and actual daylight?
Regards,
mskelly
Hi Kelly, concerning your first question (the color change) some other
parameters than the color change itself must be into consideration:
first, how did you tune the white balance of your camera? what was
the color of the background? did it have any inluence on the
automatic white balance? Is your computer screen correctly
calibrated? (calibrating a computer screen is very difficult. I am
sure that between all of us, orchidians, none of us see the same
colors at the same time. Because of the computer.)
concerning your second question (light entering from the back) it
appears that your light source is just behind the stone,
perpendicular to the table and well aligned with the culet: so it’s
clear that most of the light will be reflected instead of refracted
and entering into the stone. Just put the light asides,
perpendicular to the facets of the culet, and I’m sure that you’ll
see a difference.
But, as a priority, check the white balance, and try to get a white
photo of a white sheet of paper, in any lightning condition.
Yann GUILLEMOT www.webcarats.com