Filters/Gels for Britek (Rostronics) ?

G

gualbert

Well-known member
Team,

What kind of gels including holder is recomended for the Britek offered from Rostronics? I think the holder has to be 7" (or around) if I am not mistaken. BTW, I am looking for Filter/Gel to convert 3200K into ~5600K. (Britek 600W with softbox+Barndoors kit). Thanks in advance!!!
 
Re: Filters/Gels for Britek (Rostronics) ?

The gel you want for that is full CTB. It'll cause about a 2-stop loss in light output, so your 600w softbox will be putting out about 150 watts' worth of light...
 
Re: Filters/Gels for Britek (Rostronics) ?

But you don't use barn doors inside the softbox, do you? I don't think you could even do that, the speed ring fits in the slot where the barn doors fit, right? So for within the softbox you'd need some sort of gel frame or gel holder...
 
Re: Filters/Gels for Britek (Rostronics) ?

Thanks for the fast reply!!! I guess is not worth loosing all that power!!!
 
Re: Filters/Gels for Britek (Rostronics) ?

How does the stop loss convert to watt loss when calculating the end result?
 
Re: Filters/Gels for Britek (Rostronics) ?

CTB costs you 2 stops of light, which means you get half of half of your light output.

So 600 watts, -1 stop = 300 watts, -1 stop = 150 watts.

Each f-stop lost means 1/2 as much light, the same as cutting your wattage in half (except, of course, that you'll still be burning 600 watts of heat and 600 watts of electricity, just getting the *equivalent* of a 150-watt blue bulb out of your 600-watt orange bulb).
 
Re: Filters/Gels for Britek (Rostronics) ?

ok Barry now your just braggin cause you got those Daylight HMI's on the way to your door :)
 
Re: Filters/Gels for Britek (Rostronics) ?

Should be here Tuesday! :) Actually I've already got a couple of HMI's and daylight-balanced fluorescents, but the DayPhoto's will hopefully round out the kit nicely! ;D

But seriously, people have to understand the light loss involved in converting tungsten to daylight... if someone's considering the Britek softbox kit, but they think they might have to use it to convert to daylight color, there's no question but that you gotta get at least the 1k instead of the 650.
 
Re: Filters/Gels for Britek (Rostronics) ?

heh heh. Yes indeed.

Thank god for Kinoflo :)

I still dont know why they just dont make Daylight bulbs for these tungsten lights, even if it's just a filement tint.
 
Re: Filters/Gels for Britek (Rostronics) ?

I've seen lots of replacement incandescent bulbs advertised as "daylight", like GE Reveal, but they're not full-spectrum and they're not daylight-colored... they're nearly as orange as regular tungsten bulbs.

You can get full-spectrum daylight fluorescents for incandescent light fixtures, but not for halogen...  They're cool, inexpensive, and give off fairly decent color and light, but they're inherently soft, so you don't get any directional "punch" out of 'em.

Then again, there's daylight Photofloods... strong blue incandescents with high heat and directional punch -- but they have a lamp life of only four hours!

So for blue light you get three choices: gel your tungsten lights (cutting your light output to 1/4), use fluorescents (and give up hard light "punch"), or get the best of both worlds by getting HMI's... but pay through the nose for 'em!

That's what made the prospect of the DayPhoto's so interesting.  I'll let you know what they're like when they show up...
 
Re: Filters/Gels for Britek (Rostronics) ?

They told me on the first day of law school that if I didn't want to view everyting I see from a legal perspective that I should quit NOW. They were right.

Now that I've been learning color temperatures, conversions, and actually WORKING with them and seeing how they work on a practical level, all I can see are color temps. Do I ever see pure white anymore?? NO!!!
 
Re: Filters/Gels for Britek (Rostronics) ?

Maybe I missed it, but I don't see a good recommendation for using gels with the briteks. I don't like the clips on the barn doors for gels.

Has anyone found a better way?

-Jerry
 
Re: Filters/Gels for Britek (Rostronics) ?

We've always just used clothespins to clamp gel sheets onto barn doors. I haven't tried the Britek clips yet. The "cleaner" way to do it would be to get some gel frames that are the right size, and use those like you would scrims.
 
Re: Filters/Gels for Britek (Rostronics) ?

I posted this once already here, but the site went down twice, so maybe it was lost.

MSE (Matthews) have gel holders from 5" to 13 1/2" in 13 steps. The start at $10 at B&H. I'm certain that others have them too, but MSE was the first listing with them in the Professional Lighting SourceBook.
 
Re: Filters/Gels for Britek (Rostronics) ?

C-47's work great for attaching gel to lights.

Is everyone aware that the Britek HMI's are magnetic ballast? Not horrible but not usable with generators or inverters and a long restrike time.
 
Re: Filters/Gels for Britek (Rostronics) ?

Yeah, I've been trying to make sure people understand that. There's a fairly long warmup time (I usually let 'em burn for 10 minutes before they're up to temperature) and then there's a 10-15 minute restrike time (for those who don't know, that means that once you turn the light off, you have to wait about 15 minutes before you can turn it back on again).

For long-burn shows it's fine, but if you were trying to do a 40-setup-a-day indie feature, that wait time'd kill you...

... plus, they burn green, there's a big green spike, so you will either need to do a manual white balance using only the HMI's, or for mixed lighting you should have some MinusGreen gel handy.

Fairly minor quibbles considering the great value, but these are definitely not the one-and-only light that people should get. They have a place, and it's a pretty good place, but they can't be your versatile it-does-everything light system...
 
Re: Filters/Gels for Britek (Rostronics) ?

Is there a standard strength of minus green gel that would rid the Briteks of their green spike? I'm using a 600 watt if it matters...
 
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