daylight spectrum bulbs

[John Rumm]

Well its not *that* weird... ;-)

If you look at [1.3.3] (then compare with [1.1.1] at the top:

should see a breakdown of the typical spectrum for a CFL. These are usually characterised by lots of missing bits, with a number of predominate "spikes" in output at various frequencies.

Chances are your nice yellow paint reflects a range of frequencies centred about the yellow portion of the spectrum. With natural daylight (i.e. when the paint is reflecting light from a full spectrum source) it looks ok. With CFL illumination the paint will still reflect the same range of colours, however most of the ones that add up to give the characteristic you see in daylight, are now missing from the source. So you will instead see just the few spikes in output that the bulb can produce at frequencies not absorbed by the paint. This loses the subtlety of the colour.

Look at:

how the CFL output has a very "flat" or "solarised" look in the green regions, and very low intensities in much of the yellow. Hence nay nice subtle colour that includes a fair amount of green/yellow is likely to be rendered with most of the yellows attenuated, and all subtle variations of green reflected as one flat colour.

[dennis]

I'm not aware of any fluorescents that produce a continuous output without spikes. they are the same technology as CFL so i fail to see why they would be different.

[Tim Downie]

So you're saying that you know that no amount of jiggering around with different bulbs will ever produce a satisfactory look? I'm impressed! Or rather, I would be if it wasn't for the fact that I know from my own experience that different CFLs produce different qualities of light.

*Maybe* none of them will produce a satifactory appearance but it's sure as hell easier to try a few bulbs than repaint three rooms.

Tim

[Dave Plowman (News)]

Better phosphors. Decent specialist fluorescent tubes are perfectly satisfactory for photographic etc use. CFLs are simply cheap rubbish.

[Grimly Curmudgeon]

Tractor and Plant Yellow?

[The Natural Philosopher]

A fairly succinct and cogent summary...

[Dave Plowman (News)]

If anything, they have even more problems producing a reasonably continuous spectrum.

[Jon Fairbairn]

The colour temperature isn?t the real issue here. You need to look at the colour rendering index (CRI), which tells you how good the bulb is at revealing colours. 100% corresponds to daylight. A light source can have a high colour temperature while having a low CRI (because the only light it outputs is a few sharply defined monochrome wavelengths). Typical CFLs have CRIs in the low 80s. There are CFLs with colour temperatures around 5500 but CRI of >93, which would solve the OP?s problem. I don?t know where to get them, though.

Unfortunately, manufacturers and suppliers seem reluctant to provide the CRI.

[NT]

Let us know how it goes then :)

[Tim Downie]

Not my problem, I just think your suggestions (and attitude) are particularly unhelpful. To seriously suggest redecoration three rooms to deal with a colour balance problem produced by CFLs is just ridiculous The "science" that leads you to believe that all CFLs use the same phosphors (and hence have the same colour specturm) does not tally with my own experience of the light quality from CFLs.

Tim

Tim

[Dave Plowman (News)]

You'll get exactly the same thing with basic fluorescent tubes with some colours - although not IMHO as badly as with CFLs. CFLs seem to have been designed to *look* similar to a tungsten light when viewed directly rather than for the quality of light they produce.

With fluorescent tubes, the ones which give a more continuous spectrum are not only considerably more expensive, but produce a subjectively lower output. However, to me, both these are outweighed by the better colour rendition they provide. Others obviously don't give a toss. ;-)

[NT]

It wont be solved to anyone's satisfaction by replacing cfls. If you want to try things that wont work, that's fine, but I personally dont recommend it.

I've not claimed any such thing. Once you understand why the colour issue is happening, then you'll understand what proposed solutions can and cant work.

[John Rumm]

That really makes no sense. Different CFLs will employ different coatings, and hence have output peaks in different places. Some of those

*may* make for a more acceptable rendition of the chosen colour. However replacing one set of CFLs with another is not the only option. Replacing with linear FLs (which tend to have a much better colour rendition) is an other option, as would be switching to LED/FL or one of the various metal halide lamps. Even LV halogen would be another lower energy solution than GLS incandescents.

[Mike Tomlinson]

In article , Simon Finnigan writes

Just stick incandescents in and bugger the environment.

I can't stand the quality of light from CFLs. They have their place (e.g. external light fittings) but are not the universal panacea the greenies would have us believe.

[Mike Tomlinson]

In article , Simon Finnigan writes

I recently painted a (big!) room with B&Q own-brand paint that was supposed to be white-with-a-hint-of-yellow. It dried to a violent shade of sunflower yellow.

Had to repaint twice (with Dulux this time) to get the shade I wanted.

[Simon Finnigan]

I'm well aware of the implications of different phosphors giving different spectra of light, but I'm also aware that there may be a brand that uses differently tuned phosphors to bring in a more natural colour than others. Or I may have to use filament bulbs in those rooms, of other options, but given that my time isn't worthless it's gonna take a lot of extra electricity burnt by a few 60W bulbs to make it worth repainting three rooms :-)

I'm gonna start by trying to get a range of CFL bulbs from friends cupboards and drawers and see if any of them are better, and if so try and obtain a quantity of those. If not I'll keep looking for other ideas - it isn't particularly unpleasant as at the moment the rooms affected don't see that much use, but int time that will change.

[NT]

more or less all CFLs use triphosphor, and any bottom end lamps that don't should be avoided. The variation is in CCT, most are 2700K, a few are over 4000K. The latter are marked with the CCT, or the old fashioned names indicating high CCT like 'daylight' etc

NT