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.
