# CFL and color temperature



## Melesse (Feb 23, 2010)

I did a quick search for Flourescent and Softbox and got nothing related, which would seem odd that this hasn't been asked before, but...

I picked up a softbox at the local camera store today.  All of my currently lighting is based on hot shoe flashes, but it was only $90 bucks and I couldn't resist.  Perhaps I should have thought a lot harder, but as I was driving home I started to think about how much of a pain it might be to try and color correct between the CFL's in the softbox and my flash units.  I've looked online and apparently you can get color balanced CFL bulbs that are around 5500K, but they are around 17 bucks apiece.  

I am extremely amateur and cheap, but on the other hand I don't want to do something like mix different color temps that would gimp my picture.  How do daylight balanced CFL bulbs match up to flashes?  Would it be easier to figure out how much green is in the CFL and try and use a gel on the flashes to match?  Or should I just return it?  

If I was dead set that photography was going to be a hardcore thing for me, I would have no problem saving for and getting something nicer, but I have a bad tendency to flit from hobby to hobby, so I'm trying not to go crazy here on the costs.

Mel


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## Dwig (Feb 23, 2010)

Melesse said:


> ...How do daylight balanced CFL bulbs match up to flashes?...



Poorly.

There is another specification relating to lamps that is more important than the Kelvin rating; its the Color Rendering Index (CRI). CRI is a measure of how close the lamps spectrum matches the full spectrum curve of a standard "black body radiator" of some Kelvin temperature. A 3200K lamp and a 5000K lamp can both have the same CRI. For photographic use, its generally considered that the minimum CRI to use is 90. 100 would be a perfect fit.

Fluorescents, both conventional and compact, generally have rather poor CRIs, often in the 60-75 range, even when they are rated as a "daylight" type or 5000K. The special "full spectrum" lamps that are available at higher prices generally have CRIs in the 89-92 range. 

These "full spectrum" lamps will be a decent match to other daylight sources if they have similar Kelvin ratings and, with some modest gels on either the CFLs or flashes, can be matched rather close. Still, the best thing is to use only one type of light sources, flash _or_ CFL.


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## Melesse (Feb 23, 2010)

Alright, so basically if I decide to keep and use it, I'll need to go all CFL, ideally the same brand and manufacturing lot (as I understand the CFL can vary quite a bit in their temp.).  Well, nevermind.  I guess I'll take it back tomorrow and save for an Alien Bees set or something.

Thanks a lot!

Mel


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## Don Kondra (Feb 23, 2010)

Hi Mel,

Check the rating of the CFL's, if they are indeed for photography they will be ~5500k which is fine and won't pose a problem with your flash.

Another option is to buy the right bulbs from Alzo Digital.

Cheers, Don


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## Big Mike (Feb 23, 2010)

If you are going to be shooting moving subjects (people), then I'd suggest sticking with flash/strobe.


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## Melesse (Feb 24, 2010)

Well, I carefully read my receipt this morning and discovered that returns are only for store credit, and this store doesn't really have anything I want.  I guess I'll be doing some more research into color balanced CFL's today!  I'll check out Alzo, thanks Don. 

Mike, I have no plans for shooting sports or anything that moves quickly.  I was looking for a way to move cheaply into studio lighting to start playing around in that arena.

Mel


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## Big Mike (Feb 24, 2010)

> Mike, I have no plans for shooting sports or anything that moves quickly. I was looking for a way to move cheaply into studio lighting to start playing around in that arena.


I didn't' mean _really_ fast moving subjects like sports etc.  I meant that if you want to shoot portraits of people (vs still life (objects)), then you will be better off with flash than with constant lighting.

With constant type lights like incandescent/florescent/halogen etc. your exposure is based on the aperture & shutter speed.  Unless you have a whole lot of light, you may need to use slower shutter speeds, which can lead to blurry shots if either the camera or the model moves at all.  While you can put the camera on a tripod, nobody can sit perfectly still, so you will need to maintain a decent shutter speed...maybe it's 1/30, maybe 1/60 or 1/90 for some people....probably faster for shooting kids.

Now with flash, on the other hand, the burst of light is very short, much faster than the shutter normally is.  So the flash will freeze most movement, giving you sharp images even when you are holding the camera and if the subject is moving a bit.  

Of course, you can shoot portraits with constant lights, you just have to constantly be aware of the shutter speed and it may take a whole lot of lighting power.


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## Melesse (Feb 24, 2010)

I got it now.  

I'm just going to take it back and get the 50 mm 1.8 prime instead with the store credit.  My flashes are apparently between 5600K - 5900K, and due to the issues you brought up and that fact that I really don't want to get into color temperature problems means it would just be less of a headache at this point in time.  

Thanks again Mike.

Mel


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## Dwig (Feb 24, 2010)

Don Kondra said:


> Hi Mel,
> 
> Check the rating of the CFL's, if they are indeed for photography they will be ~5500k which is fine ...



That is, if they are indeed for photography they will be roughly 5000-5500 Kelvin _and have a high (>=90) CRI_. Cheap lighting kits may have 5000-5500 Kelvin lights that have a lower CRI that will produce moderate to significant color matching issues. With lower CRI lamps you will find that when you properly balance a neutral hue (gray to white) most colors look fine, but some will be incorrect, more often undersaturated and/or dark but sometimes overly light. Typical low CRI fluorescents yield light, yellowish greens and dark, dull reds even when white balance is carefully adjusted to yield clean grays and whites.


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## Don Kondra (Feb 24, 2010)

That is why I always recommend the Alzo Digital lights, they are 5500k and have a CRI rating of 91...

Replacement Photo Light Bulbs from ALZO digital

NOT the same as the "daylight" bulbs available at your local building supply  

Cheers, Don


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