Again, thank you very much for your input
--- Anthony Farr <[EMAIL PROTECTED]> wrote:
> Sorry for the delay in my answer. Over the weekend
> my wife had her second
> gallstone attack in three weeks and I'm only just
> clearing my PDML backlog
> :(
>
> In answer to your question, you need to remember
> that most things in nature
> are lit from one source (the sun, the moon, a fire
> etc.) so a shot should
> appear to be lit by only one light. That is the
> main light and can go
> anywhere that looks good and is appropriate to the
> subject and the purpose
> of the photo. However the main light alone will
> create shadows that are too
> dark for film to render, so a second light called
> the fill light is used,
> but it shouldn't contribute any shadows of its own.
> That is why the fill
> light is always as close to the camera as possible
> (unless reflections might
> be problematic ie. portraits of eyeglass wearers).
> The spread lighting you
> describe is ideal for a copystand but is rarely
> satisfactory for 3D
> subjects, and will create a nest of crossed shadows
> that are difficult to
> handle.
>
> To arrive at the lighting ratios is simple. The
> whole subject from the
> camera's point-of-view is lit by the fill light.
> The main light illuminates
> only the highlights and does not reach the shadows.
> If the amount of light
> reaching the subject from each light is the same,
> then the shadows get one
> measure of light (from the fill) and the highlights
> get two measures of
> light (one from the main plus one from the fill).
> The result is a 2:1
> lighting ratio.
>
> So, if half the light reaches the subject from the
> fill as it does from the
> main then the shadows have one measure of light
> (from fill) and the
> highlights have two (from main) plus one (from fill)
> equals three measures
> of light therefore the lighting ratio is 3:1. This
> simple arithmatic
> provides the lighting ratio for any illumination
> difference.
>
> When you add more lights, eg the background light
> and the "hairlight" (named
> for its purpose in portraiture, also called a
> "kicker" on movie sets) you
> need to take the latitude of the film into account.
> The kicker should be
> one to three stops above the general exposure level
> of the lit subject,
> depending on how strong an accent on the back edges
> of the subject is
> required. The background light is mostly a subtle
> splash of oblique light
> for compositional balance which should be about the
> same as the general
> exposure. But if you're aiming to get a totally
> white field then you need
> to overlight it about a stop (by INCIDENT light
> measurement) to achieve a
> pure white. Alternatively aim for a REFLECTED light
> meter level about three
> stops above the subject level for colour film or
> four stops higher for b&w
> film. This puts white one stop into the shoulder of
> the film's curve, and
> prevents any greyness. This isn't as easy as it
> sounds because you mustn't
> spill background light onto the subject or introduce
> erroneous shadows.
>
> If all this sounds complicated the solution is to
> experiment and the
> principles will fall into place. Anyway, if it was
> too easy then
> professionals wouldn't get paid to do it :)
>
> Regards,
> Anthony Farr
>
> ----- Original Message -----
> From: "MPozzi" <[EMAIL PROTECTED]>
>
> (snip)
> > -I have a light meter, and I will be using that to
> > measure light, however anthony, i do not
> understand
> > when you say...
> > "Both lights of equal brightness (always measured
> at
> > the subject) will give a 2:1 lighting ratio which
> is
> > low contrast (ie. good for high contrast subject
> > matter). "
> > Surely 2 lights, same distance from the object (on
> the
> > left and on the right) will balance out and kill
> > contrast.
> >
> (snip)
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