CTB proximity to lights!

Cooling a 500W tungsten source with CTB is going to make for a pretty meager source. Using CTB in front of a softbox is going to make for even less output. It will certainly work and you will have no issues with damaging the gel, but the light output may be a bit disappointing.
 
Yes, on a recent shoot we had JTLs and put several 12"x12" CTBs on the diffusion surface using wood clothes pins. I'm assuming the softbox has vents on the side and top to let heat escape.

Joe C.
 
Like Khmuse said, you wont have any problems with heat concerning the gels, softboxes as diffusion also reduce the heat output significantly. What the problem will be however, is that 500W is a scarce amount of light to begin with... Adding a softbox will generally bring you down 2-3 stops, and with the addition of a (for example, whole) CTB, that is going to be another 1-2 stops...Which leaves you with not a whole lot of light power left. Possibly consider replacing your JTL with something stronger. Best of luck!
 
I know about the lost of light due to the CTB. I do have some other lights I can use but they happen to be the stigmatized work lights which more than likely will melt the blue gels. I'll stop there before another war descends upon us.

I just ordered the CTB so I can't do any tests right now but I wonder if I take the screen out of the softbox and just use the C-47s to attach the gel if that would be fine too. In other words, subtract the screen but keep the outer box there. I'll have to wait and see.

Thanks for the info.

Jgastelb
 
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That should help make a much more useful source. The distance will keep the heat down enough to not effect the life of the gels much at all. This is a much better solution.
 
Could I place the blue gels on the outer silk/difussion sheet that comes with it without it melting???
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I often use Lee CTB gels attached to the barn doors of an arri 800W and 1000W and they always survived the heat. Just don't get'em closer than that (like directly in front of the lamp) or they'll become light yellow instead of blue in no time ;)
 
Correction and Tungsten Fixtures

Correction and Tungsten Fixtures

Depending on the fixture, and the gel manufacturer (and gel, for that matter) it'll last the longest just pinned to the barn doors-

Some manufacturers include a gel frame that fits into the diffusion slot or accessory ears - it'll burn up fastest here-

Rosco E-Color and Lee gels (2 part gels) burn (or change color) more rapidly than Rosco Cal Color, or Gam filters-

Another product to check out would be either Lee or Rosco heat shield- a relatively clear acetate sheet that will extend the life quite a bit - probably 2-3 times normal- I use it on 1K Par 64's in the gel frames and can get 6-8 hours before it starts to change color with E-Color or Lee filters corrections-


Good luck-
 
Why not get some daylight-balanced compact flos from fullspectrumsolutions? You can get 500w worth of true daylight balanced light from two bulbs for around $50.
 
Joshua Provost said:
Why not get some daylight-balanced compact flos from fullspectrumsolutions? You can get 500w worth of true daylight balanced light from two bulbs for around $50.
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I looked at the website. Are you referring to just the bulbs? I can't find the 250watts for that price though.
 
These ones are the equiv. of 250w on tungsten light for $26 each. These are real full-spectrum (not just blue-tinted) with a decent CRI. Will run much cooler than tungsten or halogen, cheaper, and will give a pretty soft light, with no gelling.
 
Joshua Provost said:
These ones are the equiv. of 250w on tungsten light for $26 each. These are real full-spectrum (not just blue-tinted) with a decent CRI. Will run much cooler than tungsten or halogen, cheaper, and will give a pretty soft light, with no gelling.
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Thanks for the link. I wonder if I could just put those on a clamp light from depot. They run about $10 or so.
 
Yeh, it fits a standard bulb fitting. However, the bulb is nearly a foot long and 5 inches wide. The biggest thing will be getting it in a fixture that will protect the bulb from getting bumped and broken.
 
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