I think of it this way. With a black subject, it is
going to be clear in the negative, so that lots of
light can get through and hit the photographic paper
and turn it black. The more light getting to the paper
through the negative, the blacker the paper will go.
You may have to have done darkroom processing to
understand this concept. Not trying to insult your
intelligence, but it may make it a little harder.
Now if you look at a negative film (or part of one)
which hasn't been exposed, but has been developed, it
will be black. The more light that hits it through the
camera lens, the clearer it will become.
Black absorbs light, so not much light is reflected
back into your camera from a dark subject. Hence the
subject will have little detail. So, to increase the
light getting onto the film, and hence the detail, you
need to overexpose it a little, allowing more time for
light to enter the camera.
Then read what Chris said (below) about meters
compensating for light or dark backgrounds.
Hope this helps. It seemed to make more sense in my
head than typed out :)
Jody.
> > One problem i have when photograph horse jumping,
> is on a bright
> > day-dark horse-and a darkish background like trees
> with lots of
> > greenery,if i expose normaly the horse will be
> dark,harder to see,and
> > the trees nicely exposed.I usually overexpose a
> small amount but in
> > the manual for the sf-1 for ev examples it says to
> minus (-) the ev
> > for subjects infront of dark background and plus
> (+) if subjext is
> > infront of blue sky or snow. I'm sure the book is
> correct but my brain
> > seems to say this is back wards.
>
> As a rule, if the camera sees a lot of bright
> things, it will try to make
> them darker (to roughly 18% reflectance), so a
> bright background can
> darken a foreground subject, and you might want to
> overexpose a
> bit. Conversely, a dark background can cause your
> camera to
> overexpose. This is a function of meters that
> measure reflected
> light. If you measure incident / ambient light,
> your exposure will be the
> same regardless of what your subject is.
>
> chris
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