Using An Exposure Meter; Incident Light Measurement; Exposure Meter Measurement - Hasselblad 500 C User Manual

Using an Exposure Meter

To get the best results an exposure meter has to be used intelligently. This may look like a contradiction, since we have already said
that it is an accurate light measuring instrument. But light from all parts of the subject - highlights, shadows and middle tones - falls
on the meter, so the reading it gives us is an average one for the whole subject area.
Meters are scaled to suit typically average subjects - i.e. subjects with average areas of light, dark and middle tones. So if you point
the meter at a subject of this kind, the exposure reading will be correct.
But if the subject is not average - if there are large highlight areas and little shadow, or large shadow areas with few highlights - then
you have to modify the exposure reading to obtain the best results.
So there is more to using a meter than just pointing it at the subject and accepting without question the reading indicated.
The usual method of using a meter is to point it directly at the subject. This gives the correct exposure reading provided the subject
has an average mixture of highlights, shadows and middle tones. But if there is a large bright area, or a large dark area, the best
method is to go near to the main subject and take a close-up reading. For example, if the subject is a figure against a white or dark
background, by going closer you will reduce the amount of background affecting the meter and therefore get a reading in terms of a
more average subject, which is what you want.
For some subjects you can take a reading from really close up, aiming the meter at the part of the subject that you want to make sure
has optimum exposure. For instance many photographers take a close-up reading of the sitter's face in portraiture out-of-doors you
can take the reading from the back of your hand instead of going up to the subject.
If you cannot go close up to a subject that needs a close-up reading, then try to find something near at hand that is similar in tone to
the subject, and take a reading from this.
When taking readings of general scenes including a good deal of sky, you have to tilt the meter down slightly to reduce the area of
sky "seen" by the meter. The sky is a bright highlight, and by tipping the meter down to exclude some of it, the subject becomes
"average" in tone range.
Open views, such as distant landscapes, usually have very light shadows, so you can give a shorter exposure than the meter indicates.
It is usual to give half the exposure - i.e. use double the shutter speed, or use one stop smaller.

INCIDENT LIGHT MEASUREMENT

Another method of assessing exposure is to measure the strength of the light falling on the subject instead of that reflected by it. But
if you point the meter straight at the light you get a a much higher reading than if you point it at the subject. So the light has to be
cut down for the meter to indicate the correct exposure. This is done by fitting a white diffuser supplied with most meters over the cell
of the meter which is designed to reduce the light just the right amount. It also serves another important purpose, and this is to
ensure that the meter includes all the light falling on the subject over an angle of almost a full 180 degrees.
The incident light method is particularly useful for reversal colour films, and for subjects with contrasting backgrounds when it s
impossible to make a close-up reading.
To take a reading, the method is simply to turn your back on the subject and point the meter in exactly the opposite direction. If the
main light - say the sun - is coming from the side, don't just partly turn round and point the meter at this; turn round completely, and
let the main light strike the meter at the same angle that it strikes the subject.
If the light on the subject is different from that on yourself at the camera position (say if the subject is in the shade, and you are in
the sun), go up to the subject and take the reading, pointing the meter towards the camera position.
AGAINST THE LIGHT subjects are extreme cases of non-average tone range. The main lighting becomes a very bright highlight in the
field of view, so if you point the meter straight at the subject it will indicate too short an exposure and give you a silhouette effect in
the final picture.
This is all right if you want a silhouette. But if you want correct exposure for the subject, you should either take a close-up reading, or
take a reading from the camera position and give four to eight times the exposure indicated.
COLOUR FILMS have little exposure latitude, so particularly careful reading is advisable. The meter is used in the same way as for
black-and-white films.
Because of the importance of the highlights, if you are using a meter from the camera position for an against the light shot, it is best
to only double the reading, and not multiply it four to eight times as recommended for black-and-white negative films.

EXPOSURE METER MEASUREMENT

For normal reading point the cell of the exposure meter (usually in the
winding knob of the camera) at the subject while observing the latter on
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