Wednesday, April 22, 2009

What is a Full Spectrum Light Bulb

There is no across the board "official" definition of the term full spectrum. So for each manufacturer you may find slight variances. Full Spectrum light bulbs are generally linear fluorescent light bulbs and are identified by their color temperature. Anything with a 5000K color temperature combined with a high CRI is classified as full spectrum according to Philips.

Essentially it's a light source that has a cool temperature (5000K) and a color rendering (CRI) of as close to 100 as possible. Philips has several linear fluorescent light bulbs that fit in their definition of full spectrum. They are called Colortone 50 bulbs or have the code "C50" in their ordering code.

Holly Eddins


Halogenica said...

Very informatie site, but this can't be right?

Full spectrum light bulbs are identified by their CRI (colour rendering index), not their CCT (correlated colour temperature).

Fluorescent lamps of 5000K or over are called usually called daylight lamps.

Flourescent lamps with CRI 95-97 are called full spectrum lamps.

Most full spectrum lamps are daylight coloured, but not all, and not all daylight coloured lamps are full spectrum. To be sure it's a full spectrum, check CRI. said...

You are partly correct and thank you very much for your comment. We had originally had in the post that one of Philips twister type bulbs satisfied the full spectrum criteria set out by Philips but it only met one criteria.

You must have both a high CRI and CCT to be considered full spectrum by Philips. Their C50 bulbs are 5000K and CRI is 92. I'm not sure where you've heard the 95 to 97 criteria but other manufacturers may have that criteria.

To be called a daylight lamp, the CRI needs to be 100. Philips considers all incandescent and halogen incandescents to be the closest they have to daylight or will allow items that are being lit to be as close as possible to the color they are in natural daylight. Now, they also have a collection that has a blue tint to the bulb that they call their Natural Light collection. This would be equivalent to Sylvania's Daylight collection and Ge's Reveal collection.

You are correct in saying that "Most full spectrum lamps are daylight coloured....and not all daylight coloured lamps are full spectrum." but you also need to review the CCT and the CRI.