2. FILTER
In strict photographic terms, a filter is something that allows certain types
of light to pass through it and blocks (or reduces) other types of light.
Filters are transparent materials which modify light passing through
them.
Camera filters are used in front of the lens , lamp filters in front of the light
and enlarger filters mainly in the lamp house of the enlarger.
Filters fitted to lenses are of 3 main types:
1. Glass filters are the most expensive and the most long-lasting
2. Optical Resin are a special form of plastic - they are cheaper than
glass but they are more easily damaged by scratches.They are
normally supplied as squares (available in 3 sizes) that fit into special
filter holders.The best known makes are Lee and Cokin.
3. Gels are extremely delicate and are easily scratched. Their main use
is for 'slot in' filter holders. Some 'gels' are now made from polyester,
which is more durable and which, unlike gelatin, can be cleaned.
3. The Filter Factor is the amount of exposure adjustment needed because of the
loss of light that certain optical filter absorbs as light passes through them.
Filter Factor
[ Exposure: The amount of light reaching a light sensitive material ]
It depends upon- (a) the colour of the filter as well as its
thickness
(b) the colour & intensity of the light
(c) the colour of the subject
( d) the colour sensitivity of the film
Generally, the deeper the color of the filter; the more light it holds
back and thus, higher the factor.
4. Filter factor can also be expressed in terms of the required
exposure value correction. Exposure value correction figures are
usually given in half or hole the number, -1/2 EV corresponds to a
filter factor of 1 1/2X, -1EV to 2X etc.
A filter factor of 2X means doubling the exposure ( i.e. increase of
exposure by 1 stop), 4X means increasing the exposure by 2 stops.
The exposure value correction is always a negative number (by using
filters , required exposures are to be increased and hence , they
reduce the exposure value settings.
5. Types of filters
1. Polarizer filter
2. Neutral Density filter
3. Neutral Density Graduated (ND Grad) filter
4. Coloured filters
5. Skylight / UV filter
6. Special effect filters
6. Filters for today’s photography
FilterType Primary Use Common Subject Matter
Linear & Circular
Polarizers
Reduce Glare
Improve Saturation
Sky / Water / Foliage
in Landscape Photography
Neutral Density (ND) Extend ExposureTime
Waterfalls, Rivers
under bright light
Graduated Neutral
Density (GND)
Control Strong Light Gradients
Reduce Vignette
Dramatically Lit Landscapes
UV / Haze
Improve Clarity with Film
Provide Lens Protection
Any
Warming / Cooling Change White Balance
Landscapes, Underwater,
Special Lighting
10. Polarization Photography : Wide Angle
Lenses
It is recommended
to use bigger
mount filter than
the original lens
mount with the
help of step-up
ring to avoid
vignetting.
Vignette of the Sky
(In photography &
optics, Vignette is a
reduction of an
images or saturation
at the periphery
compared to the
image center)
13. Multi- Coated Polarizer:
Multi-coated to minimize reflection at the filter surfaces which
reduces flare and ghosting. MC Polarizer filter also eliminates
UV rays to remove haze from outdoor shots.
What Is Lens
Flare?
Lens flare is when
sunlight or artificial light
shines back into the
camera lens and hits the
film or digital sensor
often creating a polygonal
shape, or balls of light in
photographs, which may
vary in color.
Ghosting:
Ghosting, like flare , is
due to reflected light
hitting the sensor.
However in this case,
the reflections appear as
more bright & more
distinct points in the
image.
De-Hazed
Haze
14. Neutral Density Filter
Neutral Density filters reduce the light that is able to enter a
lens, and as they affect all wavelengths equally they have
(at least in theory) no effect on colour.
USE: Photographers will
typically reach for these when
the conditions don’t allow a
long enough exposure for the
desired result, such as when
trying to shoot for a few
seconds in fine conditions or
for particularly long
exposures in darker ones.
For this reason they are often
used for land and seascapes, to
blur the movements of water
or clouds.
18. Coloured Filters
• Coloured filters are used primarily for black and white
photography, as a means of controlling tone rather
than colour.They work by filtering out certain
wavelengths of light while letting others pass
through, and by doing so they change the contrast
between different areas.
The use of a yellow filter results in a
slight boost to contrast, and is
particularly effective in portraiture
as it covers up blemishes.
Orange filters offer a medium
contrast, and so are suited for
capturing landscapes where clouds
or other brighter details needs a
little enhancement against darker
details
19. Skylight / UV filter
• Skylight and UV filters are often used to protect the front of a
lens, the logic being that any damage caused to a filter is
preferable to any damage to the front element of a lens.
Both filter ultraviolet light, although
skylight filters are slightly pink in order
to compensate for the blue casts
sometimes present when shooting
landscapes and other outdoor scenes.
This was a popular choice with film
photography, although they are required
to a lesser extent today thanks to the
auto white balance systems found in all
digital cameras.
28. All colors are beautiful, depending on
personal taste.
If not used wisely or combined well,
color can cause apparel to look too
gaudy or very drab.
Harmony results when hues, values
and intensities are combined in a
pleasing way.
