ponedeljek, 09. april 2018

Namig no. 9








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.