Par

[jag3365]

What is PAR? I am referring to lighting for MH lights. I have seen the term thrown around and have no idea what it means.

 

[redxlch]

PAR = parabolic reflector
it's a spotlight

 

[salty cheese]

Originally posted by RedXLCH
PAR = parabolic reflector
it's a spotlight
Um, no.

PAR=Photosynthetically Available Radiation

 

[jag3365]

OK so what does THAT mean?? :notsure:

 

[bang guy]

It's a measure of how much useful light a bulb produces.
Lumens measure how bright an object is and is only loosely related to light output.
PAR is a better measure of light for Corals.

 

[redxlch]

This is not a PAR light?
Bulb: PAR-38

 

[bang guy]

Originally posted by Jag3365
I am referring to lighting for MH lights.

Originally posted by RedXLCH
This is not a PAR light?

The bulb shown has nothing to do with MH.

 

[salty cheese]

Here's an an example. Some can have a penedent design also.

 

[redxlch]

I understand I am incorrect regarding the acronym for PAR.. however, Philips does call the bulb above a metal halide.
Protected MasterColor® Ceramic Metal Halide Lamp
Feature: PAR Style. Open or Enclosed Luminaires.

 

[bang guy]

My sincere appologies. I thought the lamp you pictured was a Halogen. I was wrong.
Sorry...

 

[cathbad]

Par, for the lamp pictured, is short for parabolic, refering to the shape of the reflector, not photosynthetically active radiation.

 

[salty cheese]

Originally posted by Cathbad
Par, for the lamp pictured, is short for parabolic, refering to the shape of the reflector, not photosynthetically active radiation.
You are correct. The abbreviation Par in relation to that particular type of bulb means parabolic, but the original question about PAR was specifically seeking a definition of the acronym “PAR” that is used in this hobby, which means Photosynthetic Available Radiation.
Apples and oranges.

 

[cathbad]

"PAR [photosynthetically active radiation] is generally defined as the amount of radiation (quantum flux) between 400 - 700 nm wavelengths of light that zooxanthellae could potentially use in photosynthesis." (Borneman, 2001)
PAR as define as photosynthetically available radiation would seem to be more akin to PUR, photosynthetically usable radiation. "PUR is the amount of radiation that, according to pigment concentration, water clarity, etc., is actually available to the zooxanthellae." (Borneman, 2001)

 

[jag3365]

Thank you Cathbad. Finally someone answered my question.