High CRI fluorescents: any experience with Philips f32t8/tl950?

arley_gwFebruary 6, 2007

Greetings, fellow light seekers:

In the next few months I hope to be renovating an old barn and installing lots of fluorescent fixtures. The barn will be used as a combination workshop/art studio.

The quality of light is important, as I dabble in some artsy stuff and my wife has a hobby of restoring old furniture. So a good CRI is important. I have full-spectrum Excella T12s in my office, and I like them okay, but I'm going to go with T8s in the new work.

However, I only have read data on the Philips f32t8/tl950; never have seen one in person. They don't sell them individually, and I'm not too keen on shelling out $300 or so on a case of them to try them out. That's especially important in that they aren't a particularly efficient lamp in terms of lumen per watt (so I would need a fair number of them); the lamp has a design lumen rating of 1860 lumens.

Has anyone used this particular bulb or any of the other high-CRI (Lumichrome, etc) bulbs for a similar application? I can read the data, but I'd like to hear from someone's personal experience if the quality of light is conducive to these applications.

Basically, do you like them? Are you comfortable in that type of light? Can you make reproducibly accurate color decisions with them?

Thanks in advance for any advice about these or any alternative lighting schemes.

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I have used 950s in the finishing area for a cabinet shop where they apply stains and paints and color match. They are happy with them. The rest of the shop uses T5HO 741 lamps in high bay fixtures.

It does not feel warm and cozy to be in 5000K lighting, to me. It's hard to be depressed though.

    Bookmark   February 6, 2007 at 5:36PM
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Thanks for the info. I do like full spectrum lights. I got used to them in my office.

I noted something: when I was installing the FS lights one balmy evening with the door open, I had installed some fixtures with the full spectrum tubes while some others still had the old tubes. All the moths flocked to the full spectrum tubes and left the old ones alone.

    Bookmark   February 7, 2007 at 8:42AM
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Makes perfect sense... ever seen a moth with SAD?
I thought not! ;-)

    Bookmark   February 7, 2007 at 10:46AM
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All the moths flocked to the full spectrum tubes and left the old ones alone.

That figures. "Full Spectrum"* lamps are bluish. What color is the light in bugzappers? Blue. What color light do we use to minimize attracting insects? Yellow.

= = =

*BTW, "Full Spectrum" is a misnomer. That just means its color temperature (supposedly) approximates noon artic sunshine. The manufacturers typically mix three phosphors to get better control of the light color. A spectral analysis will show three peaks. Unlike sunlight, it's not an even mix of every color.

It may even be less than three for the Philips TL950. I don't know about the 950, but I've read that the warmer TL930 actually is a halophosphate phosphor lamp, rather than a triphosphor type. It even uses a yellowish coating on the lamp to get the desired CT. If the 950 uses a bluish coating for the same reason, that might explain its relatively low efficacy.

This is not to suggest there's anything wrong with those lamps, just that with any fluorescent, "full spectrum" is usually more ad-speak than reality.

    Bookmark   February 7, 2007 at 5:44PM
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I was playing around with a spectrophotometer (used primarily for making custom color profiles for printers and computer screens) last week and measured the light spectrum of some incandescent and CFL bulbs. Although the CFL bulbs were not "full spectrum" and only had a rated CRI of 80, you could easily see the spikey nature of FL lamps. From a perception standpoint there was a huge difference between the 2700K and 3500K CFLs. Personally the 2700K bulbs have a sickly yellow/orange glow whereas the 3500K bulbs seemed a bit too cool. A 5000-5500K "full spectrum" FL might come across as being rather icy.

Someday I hope to try a Solux lamp for color matching prints. They are suppose to have a continuous color spectrum very close to daylight with a CRI nearly 100.

    Bookmark   February 8, 2007 at 1:00AM
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Yes, even the best high-CRI fluorescents have a spiky spectrum. That's why I appreciate the comments of those who have had real world experience with these items.

Judging the quality of light is a bit like evaluating stereo components. Measurements, while important, can only take you so far, and your subjective response has to be the final arbiter. I had a dinky 35 watt per channel tube amplifier that sounded much more musical than a $$$ solid state unit.

Within the next few years we'll see huge changes in lighting. I read recently that they now have LED's that are 1.7 times as efficient as the best fluorescents (in terms of lumens per watt consumed). As the price of energy continues to go up, I'm sure LED-based lamps will eventually replace incandescents. It'll be interesting to see what quality of the light is produced by those things.

    Bookmark   February 8, 2007 at 11:06AM
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Sorry to have been so unhelpful to you by including a bit of data. I know your looking for personal opinions, so can't help you there with that particular bulb. I think you know the answer to your question as you implied in your description of your stereo amplifier.

Quality of light is a very personal thing. Just like your stereo, no one else can say anything that is more meaningful than your auditioning a particular light. Maybe a very large lighting supply house has something similar on a piece basis. Verilux sells small quanities of medium bi-pin tubes on their website, and these are said to be "full spectrum".

Having been a professional architectural photographer I am very sensitive to light as well and in general find all fluorescent lights to be comparitively offensive regardless of CRI. Afterall, CRI is just another one of those meaningless quantitative measurements. Science can sometimes be pesty, but it's hard to resolve a spiky color spectrum with an environment conducive to excellent color matching over a broad spectrum. To key off your analogy, incandescent bulbs are akin to your tube amplifier with it's nice warmth and harmonious spectrum, and fluorescent bulbs are more like a lousy non-linear solid state component.

Flurorescents can start instantly without flicker or hum and have an acceptable color temperature and they still can't fool you into being anything else but a florescent. They do save energy and generate less heat and other than incorporating mercury in their design, they are positive from an environmental standpoint.

I'm right with you on the LED front. I want this to happen more than anything else in the lighting world, but I believe it's a bit further out than the next few years. The multi-LED bulbs which generate the same lumens as a reasonable incandescent are still wildly expensive and not all are dimable. Dimming without change to color temperature is one of the potential great aspects of LED lighting. Thermal management is an issue as you start ganging up lots of small LEDs or use single power leds. Was looking at a picture of an undercabinet LED fixture and it built heat sink fins into it's design to address these thermal issues. Sure hope that companies like Lumileds and Cree can make some breakthroughs in this type of lighting so they can move beyond specialty applications.

    Bookmark   February 8, 2007 at 5:46PM
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Gordonr, I appreciate the data; by no means was it unhelpful.

Maybe the best solution for 'generally good' lighting for my application might be to get decent high-CRI fluorescent for general lighting and some Solux incandescents for really critical work.

Being an analog guy in a digital world, I'll continue to shoot my Rolleiflex 2.8E2 loaded with Provia, in the midday sun :)

    Bookmark   February 8, 2007 at 6:35PM
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I am a lighting designer and I have samples of these lamps.
I know this post was from a year ago, but I wanted to mention that the Philips lamp also comes in a 930 version which is 3000°K lamp, not 5000°K, and is much warmer.
The 930/950 lamps are great for locations where color is very important.
My clients consistently pick the 930 over all the other lamps when they see an actual mockup.
Yes it is true that they are not as efficient, so if you need high levels of light in a work type environment, then it might not be the best choice.
I do hope that the LED market will eventually replace fluorescent, but its a long time off and still very expensive.

Good Luck.

Here is a link that might be useful: eclectic precision

    Bookmark   February 18, 2008 at 3:12PM
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I've used both the Philips TL930 (95CRI) and TL950 (98CRI) 4-foot tubes., which fortunately I was able to buy two at a time from the local retailer. The TL950s illuminated my kitchen; the 930s went into a basement rec room where they match the color temperature of halogen downlights.

The TL950s won't blow you away upon first turning them on - they look like typical cool/sunlight fluorescents at first. Its just that the different colors really pop out well and cleanly and the colors jump out at you rather than being dulled. The kitchen there has no windows, and in the morning sunlight, I noticed the ambient light from the windows across the apartment matched the TL950 light in the kitchen perfectly. If I take pictures with a film camera loaded with standard color film (daylight-balanced), pictures taken with available light indoors under typical "cool white" fluorescents lend an awful greenish cast to everything, but those shot under TL950s had perfect color. That says boatloads about the TL950's color accuracy.

As for the lower lumen output, I compensated by overdriving them with special fluorescent ballasts, witch overdrive the bulbs by about 25%.

There are (were?) 2700K, 3500K, 4100K, and 6500K versions of these bulbs sold in Europe. Too bad they aren't sold in North America.

    Bookmark   June 23, 2008 at 4:18AM
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eLightBulbs.com sells these seperately

    Bookmark   February 26, 2013 at 10:39AM
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