|
Full Spectrum Bulbs
As an alternative to ordinary lighting, full
spectrum light bulbs try to match
the light
output of the sun with the same
relative
distribution of energy. The result
is better
contrast, truer colors, and more
natural
illumination.
Facts to compare when looking
at full spectrum
light bulbs are:
- Color temperature - this measures the visible
energy distributed over the spectrum as if
it were a simple linear scale, expressed
in degrees Kelivn or Celsius degrees above
absolute zero. The sun overhead at noon measures
roughly 5300 Kelvin (depending on the day
and place), so look for values within a few
hundred degrees of this.
- Color Rending Index - the CRI indicates how
true colors appear under that light up to
a perfect value of 100. Office fluorescents
rate somewhere in the low 60's. Look for
bulbs better than 90, preferably better than
93.
- Light output - Lumens are the standard measure
of light output not watts since watts measure
power dissipated, largely as heat. There
is a rough correlation between the light
that incandescent light bulbs put out and
the power they consume, so other lights indicate
their equivalence as a convenience for replacing
them. A one hundred watt bulb generates about
1750 lumens.
- Lifetime - this is how long the bulb may
be expected to last expressed as hours of
service. Obviously, the longer you may use
a bulb before it burns out and you have to
replace it is better. Balance lifetime with
cost and the inconvenience of replacing the
bulb.
- Type - full spectrum bulbs may be found in
three technologies:
- incandescent bulbs are regular light bulbs
with an interior coating that filters the
wavelengths of light that the burning filament
emits at a corresponding cost in light output.
These bulbs come in packages like ordinary
bulbs, but for a purplish color, they are
frequently found in the elongated version
used for fish tanks and plant lights. Flood
light versions are also available.
- flourescent bulbs come in the typical long
tubes or horseshoe shapes. Fluorescent light
bulbs work by capturing the energy from the
electrically excited gas inside them in the
interior coating of the glass and radiating
it as visible light. Full spectrum light
bulbs have a somewhat different interior
coating to adjust the light that the coating
radiates.
- compact fluorescent bulbs combine the size
and quick starting of incandescent bulbs
with the power savings of fluorescent. While
costing more to purchase than either incandescent
or regular fluorescent, the cost is offset
by the much longer life when compared to
incandescent and the ability to work in ordinary
fixtures when compared to regular fluorescent.
|
|
|
