[TheForge] Mastermyr photo question...

Sat Feb 7 19:54:04 2004

Not quite correct.
Exposing based upon an 18% gray card will let the exposure values fall where
they will (i.e. where they should).
A subject with darker skin will therefore expose as a darker skinned subject.
Adjusting the exposure from 18% gray toward a smaller aperture opening (higher
f-stop number) will underexpose the dark skinned subject, as well as everything
else in the photo.
If you set your exposure settings based upon a darker gray, then the camera
will "assume" it's really 18% gray with less light, and will give you settings
to overexpose it to the point of getting back to18% gray.

Shoot a white piece of paper based on the camera settings and you'll end up
with 18% gray.
The camera meter doesn't know it's white, it figures it's 18% gray extremely
well lit, and will adjust the exposure (underexposing it) to bring it back to
18% gray.

If you want to use 18% gray, meter an 18% gray card, set the camera to those
settings, and photograph something black and it will show as black. Photograph
something white and it will show as white.

A little tip for anyone who doesn't want to carry around an 18% gray card with
them is to take a reading off the palm of your hand and make a note of the
difference between it and 18% gray. Mine is 2/3 of a stop brighter than 18%
gray. Anytime you want to take a picture in ambient light (i.e. non-flash),
take a reading off your palm in the same light as the subject. Adjust your
camera accordingly and shoot away.
Your pictures will be as well exposed as if you had used an 18% gray card.

And photographers don't use gray backgrounds for exposure purposes.
Every pro I know uses a light meter for light readings.
They use gray because it's a neutral background.

Bob

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Mike McKim
Sent: Friday, February 06, 2004 9:40 PM
To: [email protected]
Subject: Re: [TheForge] Mastermyr photo question...

The use of 18% gray cards as an exposure reference in photography relates to
photographing a typical Caucasian face. Where the subjects melanin
concentration is generally higher a greater % gray card is used as a
reference which results in a lower f-stop.

Mike McKim