CHanging color temp on work lights.

A

abeas

Well-known member
I bought 2 of these Husky 65watt fluorescent work lights to flood a stage. Of course I didn't realize the bulbs were 6500k when I bought them.
I'm sure people frown upon work lights but it's what I could afford for now. I have not been able to find any other bulbs with a lower color temp (looking for 3.2k) so I'm thinking gels. I have no idea how to measure color temp or even take a guess as to what gels I should buy to get close to 3200. Can some lighting experts shed some "light?"

These are what I bought.
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053
 
Or replace the lamps with like size 3200k mogul base fluorescent lamps so you don't loose your intensity by using a full CTO gel.
 
I did too, and I got the same results as you. I guess mine isn't a Mogul base, despite what the specs say. I'll have to keep searching for the lights.
 
abeas said:
I bought 2 of these Husky 65watt fluorescent work lights to flood a stage. Of course I didn't realize the bulbs were 6500k when I bought them.
I'm sure people frown upon work lights but it's what I could afford for now. I have not been able to find any other bulbs with a lower color temp (looking for 3.2k) so I'm thinking gels. I have no idea how to measure color temp or even take a guess as to what gels I should buy to get close to 3200. Can some lighting experts shed some "light?"

These are what I bought.
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053
Click to expand...

Why do they need to be 3200K? Can you take them back and get quartz halogen models?
 
abeas said:
I bought 2 of these Husky 65watt fluorescent work lights to flood a stage. Of course I didn't realize the bulbs were 6500k when I bought them.
I'm sure people frown upon work lights but it's what I could afford for now. I have not been able to find any other bulbs with a lower color temp (looking for 3.2k) so I'm thinking gels. I have no idea how to measure color temp or even take a guess as to what gels I should buy to get close to 3200. Can some lighting experts shed some "light?"

These are what I bought.
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053
Click to expand...

Let's use the mired system to work out the amount of correction you need. Read about it on page 6 here: http://www.rosco.com/includes/technotes/filters/FilterFacts09.pdf

6,500 divided into 1,000,000 = 154 mired
3,200 divided into 1,000,000 = 313 mired
You want to go from 154 to 313 so the mired shift is 313 - 154 = +159

A mired shift of +159 is just what you get with full color temperature orange gel. So if you put full CTO on your light it will hold back the heavy blue colors but let the warmer tones through. The problem you have is that because it's a fluorescent you don't know how much warmer colored light your bulb produces and therefore how much light will make it through the filter. You can't use the gel manufacturer's light transmission or loss numbers because they don't apply to a source like yours. So just get a piece of CTO and try it. My guess is that you will have less than half the light remaining, a loss of at leas one stop.

The other problem you have is that your lights are unlikely to render colors accurately so skin tones, for example, might look quite bad under the unfiltered lamp or with the CTO.

I understand not having the money to get everything you want. I think you would be better with scoop lamps and photoflood globes or worklights with quartz halogen bulbs. The former are usually already 3200K and the latter are usually around 2800K and can be moved up to 3200K without much loss and with good color fidelity.

If any of this doesn't make sense just ask and any number of people can explain some more.
 
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Thanks for the info. They need to be 3200 because they will see more indoor use than outdoor. As far as Halogen goes, a lot of events I shoot have young kids walking around and touching things. No matter how many signs you put up or ask nicely, people touch things, and trip on stands and risk getting burnt from the heat of the light. That's my concern and why I chose fluorescent lights.
I think I'll keep looking for indoor colored lamps for them for the time being.
 
abeas said:
Thanks for the info. They need to be 3200 because they will see more indoor use than outdoor. As far as Halogen goes, a lot of events I shoot have young kids walking around and touching things. No matter how many signs you put up or ask nicely, people touch things, and trip on stands and risk getting burnt from the heat of the light. That's my concern and why I chose fluorescent lights.
I think I'll keep looking for indoor colored lamps for them for the time being.
Click to expand...
Okay, but remember, shooting indoors during the day usually means adding your lighting to what is coming through the windows, so daylight sources are dandy.

Ah, the kids. Okay, makes sense. Be sure to put a couple of sand bags on each stand and make sure the power cables are not "clotheslined" where they hang from the stand or the outlet above the floor, and my favorite, be sure the power cable is laid out flat on the floor instead of with coils standing up. After that some gaffer tape along the runs and you are good.
 
slondon said:
Let's use the mired system to work out the amount of correction you need. Read about it on page 6 here: http://www.rosco.com/includes/technotes/filters/FilterFacts09.pdf

6,500 divided into 1,000,000 = 154 mired
3,200 divided into 1,000,000 = 313 mired
You want to go from 154 to 313 so the mired shift is 313 - 154 = +159

A mired shift of +159 is just what you get with full color temperature orange gel. So if you put full CTO on your light it will hold back the heavy blue colors but let the warmer tones through. The problem you have is that because it's a fluorescent you don't know how much warmer colored light your bulb produces and therefore how much light will make it through the filter. You can't use the gel manufacturer's light transmission or loss numbers because they don't apply to a source like yours. So just get a piece of CTO and try it. My guess is that you will have less than half the light remaining, a loss of at leas one stop.

The other problem you have is that your lights are unlikely to render colors accurately so skin tones, for example, might look quite bad under the unfiltered lamp or with the CTO.

I understand not having the money to get everything you want. I think you would be better with scoop lamps and photoflood globes or worklights with quartz halogen bulbs. The former are usually already 3200K and the latter are usually around 2800K and can be moved up to 3200K without much loss and with good color fidelity.

If any of this doesn't make sense just ask and any number of people can explain some more.
Click to expand...

I'm going to buy a prism and a diffraction grating in the next few days... I know that some people may think this is taking DIY a bit too far... but I'm going to see if I can get some actual spectra of various 'non-pro' light sources...

On the 'correction' needed calculations... doesn't that presume the source is 'flat' over the visible spectrum... or at least matches what the Sun and Tungsten have for spectra?
 
j1clark@ucsd.edu said:
I'm going to buy a prism and a diffraction grating in the next few days... I know that some people may think this is taking DIY a bit too far... but I'm going to see if I can get some actual spectra of various 'non-pro' light sources...
Click to expand...
It would be great to see the spectral distribution curves for a lot of sources.

On the 'correction' needed calculations... doesn't that presume the source is 'flat' over the visible spectrum... or at least matches what the Sun and Tungsten have for spectra?
Click to expand...
Yes, thus the correction is only a first approximation. Fluourescents can be made to be fairly smooth and to mimic daylight or heated filament sources reasonably well but off-the-shelf consumer stuff doesn't. I know you know that.

I'd love to see you show us what colors really come out of that worklight.
 
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