Castorama Compact Fluorescent 20 W

To keep our tests of LED lamps in perspective, we've decided to compare them to some ordinary light bulbs we've found near us.  This one is a compact fluorescent energy-efficient bulb from our nearest hardware store.

Note that this isn't an LED lamp, but uses a fluorescent tube.

Lighting

This is our photo lab which has a black wall and the light intensity measured in lux in different areas.  The bulb is 1.86 m back from the wall.  The light is more powerful than anything we've found with the best round LED lamps and comes to close to a 60 W incandescent bulb.



The lighting is warm, and photographs have a distinctive orange/red tinge.

Energy Consumption

Our equipment registered energy consumption that varies between 17.9 and 19 W.

Spectrum

The graph below isn't an example of a wide, even spectrum—quite the opposite in fact.  We produced these spectra using an i1 Pro sensor from X-Rite.


The ideal colour spectrum should be even, with even intensity across all of the colours in the spectrum without any peaks or troughs.  As you can see, though, this bulb is a long way from achieving that.  The technology isn't to blame, though, as Viva-Lite's bulbs, which are also compact fluorescents, produce a much wider spectrum.  On the other hand, they use more energy to produce the same amount of light.

The main problem with the uneven spectrum is the possibility of confusing certain shades in parts of the spectrum that aren't well-covered by this lamp. 

Here are our technical measurements for this lamp.  The closer the CRI (colour rendering index) and the FSCI (full spectrum colour index) are to 100, the better; the colour temperature is a matter of personal taste and depends on the type of light you're looking for.  There are no good or bad values for this figure.  We have more information about these measurements in this news piece.

• CRI: 84.2
• FSCI: 44.53
• Colour Temperature: 2549 K