Fluorescent Bulbs and Color Temperature?

C. Charles Hahn

C. Charles Hahn

CCH Auto Appearance, LLC
I made an interesting discovery today when I replaced the bulbs in one of my fluorescent ballasts in the garage. The bulbs I've been running (that came with the ballasts in the first place) are called "Cool White" -- a pretty stark and pure white color. I picked up some replacements that were "Soft White" and have more of a yellowish tone to them. I didn't even notice when I bougt them that it was different.



Well, now I've got a dilemma. Not all of my bulbs now match, but I've managed to distribute the yellower bulbs such that it balances around the room. The yellow bulbs, though the same wattage, seem to put out a lot more light and that light at times seems more like an incandescent setup would. The few pure-whites I have left do a good job of balance though.



My question is this: Would I be better off to get all matching bulbs, and if so which color temperature (colder or warmer) should I go with? Or should I leave it as a bit of both? I'm really not sure how or if I'm liking my setup as it currently sits. Since my truck is a light color, and covered in winter muck, I can't do much searching for swirls/etc. to see if that makes a difference.



Anyone else's thoughts are welcomed and appreciated. I just want to be as close to "natural sunlight" as possible. :nixweiss
 
I use 5100k(Kelvin) T8 bulbs/fixtures. That's daylight...



But, you really need 300/500 watt halogens to see swirls.



The combination ($) is best.



I also have 175 (watt) Metal Halide fixtures - very bright, but poor color rendition... (add blue) - they actually hurt my eyes.



Jim
 
With white paint I have a lot of difficulty seeing swirls using the halogens. I was surprised how flourescents seem to show them better along with a simple incandescent trouble light.



On the black car, absolutely halogens. I also use the trouble light for a different lighting perspective for this as well.
 
Bill D said:
With white paint I have a lot of difficulty seeing swirls using the halogens. I was surprised how flourescents seem to show them better along with a simple incandescent trouble light.



On the black car, absolutely halogens. I also use the trouble light for a different lighting perspective for this as well.
Click to expand...



depending on the vehicle I'm working on, I do have and use a dual-500W halogen stand, but for the most part I'm using the fluorescents without a problem.



My issue here isn't whether to replace my lighting with halogens or not, I'm much more worried about what fluorescent bulbs are the best. The 5100K T8's I have not seen in person, but I may have to check into that. Also might have to see if I need new ballasts for that setup over what I'm running now.
 
I'm looking to buy fluorescent T8 bulbs myself and have a silmilar question. Should I get the 5000k or 6500K. Any thoughts? The bulbs cost the same $2.69.
 
shelshel- I noticed you're not getting any responses here or on the other thread and I don't have anything to contribute....maybe you oughta talk to somebody at a "lighting shop". The people there oughta have a good working knowledge of such stuff.
 
Colour temperature describes the colour of a light source by comparing it to the colour of a blackbody radiator at a given temperature. For example, the colour appearance of a halogen lamp is similar to a blackbody radiator heated to about 3000 degrees Kelvin. Therefore it is said that the halogen lamp has a colour temperature of 3000 degrees K- that is considered to be a warm colour temperature. The hotter the blackbody, the cooler the colour temperature! (Note: The Kelvin temperature scale uses the same size degree as the centigrade scale, but its zero point is at absolute zero, or -273 degrees C). Sunlight can be "warm" or "cool" depending on the time of day and the ambient conditions. Warm = 2-3,000K, Mid-range = 3-4,000k, Cool = 4,000k +



Colour rendering index (CRI): A scale of the effect of a light source on the colour appearance of an object compared to its colour appearance under a reference light source. Expressed on a scale of 1 to 100, where 100 indicates no colour shift. A low CRI rating suggests that the colours of objects will appear unnatural under that particular light source. CRI is a unit of measure that defines how well colours are rendered by different illumination conditions in comparison to a standard (i.e. a thermal radiator or daylight). CRI is calculated on a scale from 1-100 where a CRI of 100 would represent that all colour samples illuminated by a light source in question would appear to have the same colour as those same samples illuminated by a reference source. To put it another way, low CRI causes colours to appear washed out and perhaps even take on a different hue, and high CRI makes all colours look natural and vibrant



Some fluorescent tubes throw a quite accurately coloured light while others are absolutely ghastly, in an attempt to chart which are better than the others, they came up with a scale called the "Colour Rendering Index", with a score closer to 100 the better. Well that is the theory anyhow where it breaks down is they only compare tubes of the same colour temperature. A "F40T12/DX" (6500°K - CRI -84) is not a better colour than a "F40CW" (4100°K - CRI -62) because they're different colours they can't be compared by CRI, but a "F32T8/830" (3000°K - CRI -86) is a better colour than a "F32T8/730" (3000°K - CRI -78) seeing these two are the same colour (3000°K) they can be compared by CRI.

JonM
 
If you really want to get silly with this go to www.kinoflo.com and order some kino unit/tubes...they are waht we use to match lighting conditions when shooting and they work wonders.
 
Your best bet is to go with cool white bulbs. Warm white do have a yellowish tinit to them. T-8 and T-12 are just sizes of the bulbs. T-8's are much smaller than T-12's. Your best bet is to match bulbs. Another good tip is to take a 4 x 8 sheet of plywood and mount 3 fixtures with the same bulbs on them. This way you prevent shadows and get direct light on the vehicle.
 
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