„Pa
naj bo luč“ je nekdo na začetku zakričal. Sicer ta luč sveti
podnevi, ponoči pa je potrebno imeti kakšno svetilno napravo. Iz
časa sveč, lantern in karbidnih svetil, smo prešli na baterijske
oziroma električne svetilke, največji razlog pa je seveda naš slab
dar za nočni vid. Žal se moramo s tem sprijaznit in pustiti tekanje
po naravi prvotnim prebivalcem – živalim. Spodaj preberi kaj je na
voljo in kaj bi ti najbolje odgovarjalo.
Začel
bom z malo teorije, ker vem, da je na trgu ogromno različnih
produktov in zaradi tega nastane zmeda, kaj vzeti, kaj je uporabno in
kaj priporočljivo.
Najprej
merske enote. Sigurno ne gre mimo tega, da ti vsak pove, da vzemi
svetilko, ki ima največ lumnov. Lumen je samo eden izmed treh
parametrov oziroma sveilinih metrov, iz katerih vemo, kako bo
svetilka močna, razdalja svetenja in čas svetenja. Poznamo watt,
lux in lumen.
Watt –
merska enota watt nam pove kako je svetilno telo močno. To seveda ne
pomeni, da večji kot je watt, bolj bo svetila. Pomeni samo, da
porabi več energije, proizvede več toplote in manj časa sveti. Ker
si nobeden ne želi, da ima pri sebi namesto svetilnega telesa,
grelno, je bolje, da ima manj vatov. Sodobne LED svetilke imajo mnogo
manj vatov kot navaden halogenske, a svetijo isto ali celo močneje.
Lumen –
merska enota, ki pove kolikšno svetlobo odda svetilno telo. Problem
nastane, ker nekatere svetilke obljubljajo veliko število lumnov, a
tega ne izpolnijo. Zakaj? Hudič je v detajlih. Ne povedo, kje so
bili ti lumni merjeni. Namreč maksimalno število lumnov pove,
njegovo svetilnost na tisti razdalji. Lumni merjeni na razdalji 2 m,
bodo na razdalji 10 m manjši.
Lux –
tretja merska enota, ki pove svetilnost na površini. Po domače
povedano, kako svetla bo površina na katero posvetimo. Seveda spet
detajl. Lux je merjen samo na eno enoto površine. Kaj!? Če je
merjen s 100 lux na en kvadratni meter iz določene razdalje in če
se premaknemo nazaj, da posvetimo 4 kvadratne metre, bo moč lux-a
samo še 25.
Sonce,
ki sredi dneva najbolje sveti proizvede na zemlji približno le 1
lumen, a sveti z cca. 15000 – 25000 lux, polna luna v jasnem nebu
pa sveti le z cca 1 – 5 lux in nekaj malega 0,001 lumnov.
Do
naslednjič.
„Let
there be light“ said someone at the beginning. Well, that light is
wisible by day, but by night we need some kind of light device. Time
of candles and carbide lanterns are over and we got to the electrical
lights, and the main reason is our bad gift of night vision. Sadly
we have to deal with that and let the night running to the original
habitants – animals. Read below what is available and what is best
for you.
I'll let
you know some theory because we all know, that on the market there is
a lot of products and the confusion is, what to get and what is
recomended.
First,
the unit of measurment. We can get trough, that everybody says „take
the light with most lumens“ Lumen is just one of three units of
measurment from wich we can know the brightnes, distance and time of
illumination. We know the watt, lumen and lux.
Watt –
unit of measurment that that says, how powerfull the lightning body
is. That doesn't mean, the more wats, the more will shine. That
means, consume more energy, produce more heat and shine less time.
Nobody wants to have insted illumination body, heated body, is better
to have less watts. Modern LED lights have less watts than regular
halogen, but shines the same or more.
Lumens –
unit of measurment tell how the bright the bulb is. The problem is
that most of the light promises many of lumens, but doesn't fulfill
that. Why? The devil is in the details. It doens't says, where was
the lumens mesured. Well, the maximall number of lumens says its
maximal brightnes at that distance. Lumens mesured at 2 meters will
be less brigth mesured at 10 meters.
Lux –
the third unit of mesurment that says the brightnes on the surface.
To say it easy, how bright will be thr surface wich is illuminated.
And of course, a detail. What? If we light a surface with 100 lux on
1 square meter from a certain distance and then we move back to
illuminate 4 square meters, the power of lux will be just a 25.
The sun
that shines on the bright day, it produce just a 1 lumen on the
surface, but it shines with a 15000 – 25000 lux. A full moon on a
clear sky shines with a 1 – 5 lux, and produce sometnihg between
0,001 lumens.
Untill
next time.
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