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06-15-2012, 01:32 PM   #1
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Which Daylight CFL bulbs?

I am considering purchasing some daylight balance CFLs as a cheap light source to supplement either my two flashes or window light.

I have found one good thread on these forums about daylight CFLs. It has a lot of info, but I'm having a hard time drawings conclusions. Will 5000k bulbs work to balance daylight / window light, or do I need 6500K?

And I'm also wondering: What color temperature are flashes? Are they designed to balance with daylight?

06-15-2012, 01:37 PM   #2
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I have daylight CFLs I bought from Home Depot. The light they produce is white with a purple tinge. I would not recommend those.
06-15-2012, 02:33 PM   #3
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QuoteOriginally posted by stainsor Quote
I am considering purchasing some daylight balance CFLs as a cheap light source to supplement either my two flashes or window light.

I have found one good thread on these forums about daylight CFLs. It has a lot of info, but I'm having a hard time drawings conclusions. Will 5000k bulbs work to balance daylight / window light, or do I need 6500K?

And I'm also wondering: What color temperature are flashes? Are they designed to balance with daylight?
We're using CFLs for art and photo print lighting, using PAR20 bulbs with temperature ratings of around 4100k bulbs, and the results are really excellent. The daylight 6500k bulbs have an undesirable bluish tinge, and I much prefer the 4100k bulbs. Actually, with digital cameras having a manual white balance setting, all you need is a grey card, and you can set your white balance exactly correct, and get really good results with most CFL bulbs, even 2700k incandescent equivalent CFLs.
- Sheldon

Last edited by sheld; 06-15-2012 at 02:39 PM.
06-15-2012, 03:30 PM   #4
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The thing is, you can't check just the temperature alone, you have to check something called Color Reproduction Index (aka Color Rendering Index).

Many brands will claim the bulbs are daylight (6500k), which in theory translates to the pure white you get from 12 o'clock sun, but most have crappy CRI ratings, so they cast greenish-blueish colors instead. If you look for a high CRI 6500k bulb though, the colors of everything turn out excellent.

Funny fact: I don't know about this from studio photography (I'm just a hobbist), but from setting up lightning for aquariums.

06-15-2012, 05:58 PM   #5
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Without looking it up, I was going to say you wanted 3500-4000 kelvin; but sheld already did. Full spectrum is what you want and I suspect you won't find it at home cheapo or wally world.
06-16-2012, 03:54 AM   #6
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QuoteOriginally posted by Colbyt Quote
Without looking it up, I was going to say you wanted 3500-4000 kelvin; but sheld already did. Full spectrum is what you want and I suspect you won't find it at home cheapo or wally world.
3500K also looks very good, about like the old Halogen lighting bulbs; and 4100k is even better with color balance slightly bluer than the Halogen lamp lighting which cinema photographers use a lot, and which is used in halogen lighting at museums and art galleries. I don't know how close 4100k is to flash color balance, which is theoretically 5500k. But CFL color isn't an exact spectrum, and I personally find that 5000k is a little bit unnaturally blue, and 6500k looks really wierd. Perhaps this is due to the CRI index, that hcarvalhoalves pointed out, but I was also looking at different temperature CFL bulbs at a lighting store where they presumably would have had all high quality CRI bulbs. If you use a grey card to set your white balance, then even incandescent 2700k CFL bulbs will actually work surprisingly pretty good for photography. My wife is an artists, and I've photographed her paintings using 2700k CFL bulbs and manual grey point setting, and the results were outstanding, with exact color on the prints.
- Sheldon

Last edited by sheld; 06-16-2012 at 04:03 AM.
06-18-2012, 08:06 PM - 1 Like   #7
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Hello Team!

Some information on the various lamps and color temperatures. One thing to keep in mind is that most sources can be dealt with by choosing the correct color balance in the camera. Even when shooting RAW this helps as it gives a starting point for color correction in SW.

If the lamp has a high CRI (Color Rendering Index), it will have a full spectrum. In matching colors, a CRI of 92 or better is required. For photography, I would expect a CRI of a similar level will give the best results.

Even though a lamp has a high CRI, it does not mean the lamps are spectrally balanced. A common incandescent lamp of about 200 watts has a very high CRI (98 or better) but the source has a yellow/red color balance (2800 to 3200K). A xenon flash lamp (typically at about 5500K) also has a high CRI, and its color balance is very much white (equal amounts of Red, Green and Blue). Color balances of 6500 are bluer when compared to an incandescent lamp but is actually about the color balance of open shade in natural daylight. Care should be taken with the lamps around 4100K to make certain the CRI is high. Typically these lamps are design to give us a large amount of light for us to SEE not render colors well. This is done by putting out mostly Green energy and just enough Blue and Red energy so we perceive a white light source.

The key to any choice of lamp is to determine what you want to accentuate of subdue. Assuming the camera is balanced to the light you are using, low color temperatures (3200 and down) will accentuate Reds and Yellows, but subdue Blue tones. 4100K lamps will subdue Reds but accentuate Greens. Blues are not affect too much. 5000 to about 6000K sources will not accentuate or subdue any color and 6500K lamps or above will accentuate Blues, improve Greens a bit but subdue Reds and Yellows. This is basic color matching theory. Typically, as we want to render ALL colors equally, we choose the Xenon flash lamp. However with any good source, and proper adjustment of the color in image manipulation SW (e.g., Photoshop), you can get good results and good color reproduction.

The bottom line, for the cost of the lamps compared to everything else, go for the good lamps. THey'll cost a bit more, but the results will be superior!

Regards,
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