The
natural light
The length of shadows decreases
as the sun rises, in the early morning shadows are long and colour temperature
alters from red to blue-white. This latter change is almos invisible to humans
because our brains perform a kind pf white balance control that ensures we see
all light as neutral white light. White balance settings, use daylightthrough
noon on a sunny day, cloudy add warmth to landscape scenes, shade when subject
is heavy shade, incandescent when tungsten light, fluorescent lighting primary
light source, flash when electrnic flash is primary light source
Pre-shadows
WB setting
When you are photographing under
a consistent light source, such as in a studio, it is possible to measure the
exact Kelvin value of the lighting and to set a specific WB to match. When
shooting outdoors under natural light, when the colour temperature of light can
be changing constantly, calculating the exact Kelvin temperature is impossible
for all practical purposes.
Fill-in flash
Fill-in flash is artificial light
to increase illumination in shadow areas, thereby reducing contrast. The
built-in pop-up flash on the camera is useful for fill-in flash but it suffers
from being positioned directly above the camera lens, which create frontal and
direct lighting. diffusing the flash will soften.
Working
in low light
Use manual exposure mode and
allow for setting slow shutter speeds via Bulb or Time setings, which enables
the shutter to be open for very long periods(minutes or even hours). To avoid
camera shake and image blur it is essential to use a tripod, keep its centre of
gravity low and avoid using the centre column, also a cable release will avoid
causing camera movement when triggering the shutter, an alternative is to use
the self-timer to trigger the shutter but this isn’t feasible when using the
Bulb/Time setting, and if the camera has it use the mirror lock-up function.
How
do I focus in low light
Most auto-focus systems in modern
cameras operate using a system known as contrast-detection. In low light
conditions contrast levels are often too low for AF to work effectively, if the
scene you are photographing contains a bright light, such as a streetlight,
that is along the same focal plane as your subject, then this can be used as
the focus point. Focus can then be lockedand the composition reframed, much as
if you were focusing on an off-centre subject. This technique can also be
applied in manual focusing mode. Another option is to use a very powerful torch
such as the IM+ candle. A third option
is to use intuitive guesswork making use of the focus distance scale on the
lens barrel and optimizing depth of field. Some professional specification
cameras have interchangeable viewing screens, enabling the standard screen to
be replaced with a special extra bright screen designed for night photography.
What
causes digital noise
Digital noise is caused by the
heat generated by the sensor, which is particularly noticeable during long time
exposures as the sensor gets hotter the longer it is charged, and by he process
of amplification used to increase the light signal at higher ISO ratings. The
easiest way to avoid it is to use only low ISO ratings, less than 400, and to
maintain shutter speeds faster than 1 second.
Also enable the NR reduction noise function on the camera.
Why
is high contrast a problem
All film and digital sensors have
a limied ability to record detail in shadows and highlights simultaneously.
Take ammeter reading of the brightest par of the scene and then calculate the
exposure fot the darkest part of the scene. Work out the difference between the
two exposures in stops and this gives you your SBR. If the SBR is greater than
the latitude of the dynamic range of the sensor then the camera will be unable
to record detail in all areas of the scene and will appear as a uniform shape.
Then use a NDG filter to event the tones, and expose sacrificing deail in the
brightest or darkest tones.
How does moonlight differ from
sunlight
Moonlight is simply sunlight
reflected off the surface of the moon. The intensity of moonlight is much
reduced, compared to sunlight, in this sense, although non-diffused moonlight is
directional, I has a quality similar to that of bounced light, being softer.
This form-giving shadows with the soft quality of omni –directional light. This
light is around 18 stops dimmer than direct sunlight. Gibbous moon +1.5 stops,
quarter +3.5, crescent +6.5, new moon impractical. The colour temperature is
roughly the same as normal daylight around 5500 K.
What
is the ideal lighting for macro photography
Soft lighting from a diffused
source due to is reduced levels of contrast, which helps maintain detail in
areas of shadow and highlight simultaneously. Early mid-morning or late
afternoon are usually the ideal times of lighting. One option is to use the
flash in conjunction with a small reflector, placed directly opposite the
flash, which will act as a secondary light source of illumination. The advantage
of this set-up is that he secondary light source can never be more powerful
than the prime source, which improves the tonal quality of the scene. Ideally single and multiple flash units
should be positioned a an angle of around 45 degrees to the subject, ans
slightly above the subject. The acute nature of this angle of light will cause
tiny shadows to form, accentuating detail and texture and adding to the overall
impression of sharpness.
How
do I cope with highly reflective surfaces.
A simple solution to avoiding hot
spots is to use a diffuser over the flash head soften the quality of light.
Can I alter the size of the light
source and quality of light
Hard light can be changed to soft
lighting by adding a diffuser o scatter the light. And soft lighting from a
large source can be made hard by reducing the size of the light source.
