CTB Filter Placement... at DVinfo.net

Kevin Randolph · March 9th, 2007, 07:54 PM

Okay, I'm currently using a Tota Light and Photoflex Softbox for my key light for interviews. I've run across a couple of situations where I need to gel the light to match daylight. So here's my question, are there any drawbacks to putting the gel inside the softbox right in front of the Tota, or should I get a bigger gel, cut it to size and place it between the front of the softbox and the eggcrate? I don't think heat should be an issue with the Bogen 12x12 gels I have now - they are advertised as compatible with hot lights - and if I open the top and bottom vents on the softbox to let the air flow...

Anyway, what are some thoughts and opinions? Any and all appreciated...

Thanks,
Kevin

Liam Hall · March 10th, 2007, 04:26 AM

Kevin, A Tota light in a softbox! Sounds like a fire risk to me. Are you sure that's safe?

Liam.

Daniel Epstein · March 10th, 2007, 09:16 AM

I have used both methods and they both can be sound.
Most gels will lose some of their color the closer and longer they are next to the light. As it ages its color correction will change so it would last longer if you put it in front of the softbox instead of the light.
If you put it between the light and the softbox make sure the gel has enough space to dissipate the heat from the light or it will be damaged rather quickly. I usually use this method when I don't have a piece of gel big enough to go over the softbox.
The Tota light and barndoors doesn't have very much depth so it is very difficult to put gels on it without burning them unless you can attach the gel to the inside of the softbox
As for the fire hazard this depends on the quality of the softbox and proper operation of the light. Make sure you open the Tota's barn doors to full wide or you can melt them. If the metal doors melt imagine what the light can do to a gel.

Kevin Randolph · March 10th, 2007, 12:23 PM

Liam, the softbox setup that I have is made for a Tota by Photoflex, so no worries, but thanks for your concern. The trick is to keep the little flaps open on the softbox so the air will circulate.

Daniel, thanks for the advice. I guess I hadn't thought through how I would attach the gel inside the softbox. I know that the Tota get pretty hot, usually hotter than my other lights. It's always the last one I turn on, first one I turn off, and last one I pack up because of this. But it does sound like getting some gels to fit on the outside of the softbox is the better way to go.

Thank you both for your input...

Kevin

Nino Giannotti · March 11th, 2007, 06:22 AM

Quote:

Originally Posted by Kevin Randolph

Okay, I'm currently using a Tota Light and Photoflex Softbox for my key light for interviews. I've run across a couple of situations where I need to gel the light to match daylight. So here's my question, are there any drawbacks to putting the gel inside the softbox right in front of the Tota, or should I get a bigger gel, cut it to size and place it between the front of the softbox and the eggcrate? I don't think heat should be an issue with the Bogen 12x12 gels I have now - they are advertised as compatible with hot lights - and if I open the top and bottom vents on the softbox to let the air flow...

Anyway, what are some thoughts and opinions? Any and all appreciated...

Thanks,
Kevin

Place the gel on the outside of the softbox for two reasons. The barndoors on the Tota are not long enough to place the gel at a safe distance from the bulb, the gel will melt or burn. Check with Lowel for safety issues. Lowel makes a collapsible gel frame that fits on the accessories mount of the light, the frame sits several inches from the bulb and it allows a lot of air space all around. You could mount this frame inside the softbox but this will give you problem #2, because there’s a lot of open space between the gel and the light some light will go thru the gel and some will scatter around the box mixing the color temperatures and reducing the effectiveness of the gel. I have precut pieces of gels for different purposes to fit on the outside of all the softboxes that I use, one piece will last you years. If you use a grid that Velcro on the inside lip of the softbox just cut it to the size of the screen and slip it under the grid, the grid will hold it in place. If you don’t use a grid cut the gel a few inches longer so it can be attached with clothes pins to the box.

The last problem of course is that the blue gel will eat-up so much light that the light most likely will not be bright enough to compensate for daylight.
Check out for more info. http://efplighting.com/?Filters_and_gels

Nino

www.EFPlighting.com

Kevin Randolph · March 11th, 2007, 10:27 PM

Thanks for the advice Nino, I always value your input. I usually use a 500w bulb in the Tota, but I carry a 750w with me also. I was thinking that if I had to ad the gel I'd swap out the bulb too. I've not had to compete directly with sunlight yet, or try to use the Tota as a key light outside, I don't think that would work at all. I just seem to run into a situation here and there where there are some stray rays that I can't completely get rid of. One one of my other threads (Feedback on Interview Lighting) there was the Phyllis shot. The shot was done inside, venetian blinds closed, and I didn't have quite enough flag material to compensate. So it's situations like that where I am thinking of with gelling my key light.

I do use the velcro grid, so I will be using it to hold the gel in place. I've read the page associated with your link several times. I just wish that your place holder banners for sponsors were being utilized.

Thanks,
Kevin

Charles Hurley · March 12th, 2007, 10:05 PM

For Chimera softboxes they make a diffusionn that's ctb. Photoflex may have a similar product.

Kevin Randolph · March 13th, 2007, 12:47 AM

thanks for the tip, Charles. I looked around at B&H and then at Photoflex's site, but no luck. That would've been too easy...

Ralph Keyser · March 14th, 2007, 01:27 PM

Just to drive home Nino's comment about light loss through CTB, remember that full CTB is nearly 2 full stops of light loss (not quite, but close enough). That means that in order to get the same level as your 500w bulb, you would need a 2000w bulb through full CTB.

Kevin Randolph · March 14th, 2007, 03:11 PM

Thanks for the clarification Ralph. After I get the gels, I'll have to do some test before I go out in the field. I've had a pretty good distance between the key and the subject in the past, I'll have to see if I can compensate with moving the light closer and switching to the 750 bulb. But it is definitely something to consider.

Thanks...

Heiko Saele · March 14th, 2007, 06:12 PM

from the pure law of physics, the color conversion and loss of intensity through a ctb must be the same no matter at what distance you put it, I'd rather put it further away from the lamp. You'd have to use a few square inches more in the first place, but then you won't have to replace it every few hours...
Outside the softbox the ctb gel should be lasting hundreds of hours (when it doesn't get hot)

Oh, and maybe a 1/2 or 3/4 ctb could be enough for the color conversion you need, and they don't eat as much light.

March 9th, 2007, 07:54 PM	#1
Kevin Randolph Major Player Join Date: Aug 2006 Location: Columbus, Ohio Posts: 423	CTB Filter Placement... Okay, I'm currently using a Tota Light and Photoflex Softbox for my key light for interviews. I've run across a couple of situations where I need to gel the light to match daylight. So here's my question, are there any drawbacks to putting the gel inside the softbox right in front of the Tota, or should I get a bigger gel, cut it to size and place it between the front of the softbox and the eggcrate? I don't think heat should be an issue with the Bogen 12x12 gels I have now - they are advertised as compatible with hot lights - and if I open the top and bottom vents on the softbox to let the air flow... Anyway, what are some thoughts and opinions? Any and all appreciated... Thanks, Kevin __________________ "... the drama is on your doorstep..." - John Grierson www.grvideo.net

March 10th, 2007, 12:23 PM	#4
Kevin Randolph Major Player Join Date: Aug 2006 Location: Columbus, Ohio Posts: 423	Liam, the softbox setup that I have is made for a Tota by Photoflex, so no worries, but thanks for your concern. The trick is to keep the little flaps open on the softbox so the air will circulate. Daniel, thanks for the advice. I guess I hadn't thought through how I would attach the gel inside the softbox. I know that the Tota get pretty hot, usually hotter than my other lights. It's always the last one I turn on, first one I turn off, and last one I pack up because of this. But it does sound like getting some gels to fit on the outside of the softbox is the better way to go. Thank you both for your input... Kevin __________________ "... the drama is on your doorstep..." - John Grierson www.grvideo.net

March 11th, 2007, 10:27 PM	#6
Kevin Randolph Major Player Join Date: Aug 2006 Location: Columbus, Ohio Posts: 423	Thanks for the advice Nino, I always value your input. I usually use a 500w bulb in the Tota, but I carry a 750w with me also. I was thinking that if I had to ad the gel I'd swap out the bulb too. I've not had to compete directly with sunlight yet, or try to use the Tota as a key light outside, I don't think that would work at all. I just seem to run into a situation here and there where there are some stray rays that I can't completely get rid of. One one of my other threads (Feedback on Interview Lighting) there was the Phyllis shot. The shot was done inside, venetian blinds closed, and I didn't have quite enough flag material to compensate. So it's situations like that where I am thinking of with gelling my key light. I do use the velcro grid, so I will be using it to hold the gel in place. I've read the page associated with your link several times. I just wish that your place holder banners for sponsors were being utilized. Thanks, Kevin __________________ "... the drama is on your doorstep..." - John Grierson www.grvideo.net

March 13th, 2007, 12:47 AM	#8
Kevin Randolph Major Player Join Date: Aug 2006 Location: Columbus, Ohio Posts: 423	thanks for the tip, Charles. I looked around at B&H and then at Photoflex's site, but no luck. That would've been too easy... __________________ "... the drama is on your doorstep..." - John Grierson www.grvideo.net

March 14th, 2007, 03:11 PM	#10
Kevin Randolph Major Player Join Date: Aug 2006 Location: Columbus, Ohio Posts: 423	Thanks for the clarification Ralph. After I get the gels, I'll have to do some test before I go out in the field. I've had a pretty good distance between the key and the subject in the past, I'll have to see if I can compensate with moving the light closer and switching to the 750 bulb. But it is definitely something to consider. Thanks... __________________ "... the drama is on your doorstep..." - John Grierson www.grvideo.net

March 10th, 2007, 04:26 AM	#2
Liam Hall Major Player Join Date: Sep 2006 Location: London, England Posts: 969	Kevin, A Tota light in a softbox! Sounds like a fire risk to me. Are you sure that's safe? Liam. __________________ Writer-Director-DOP www.liamhall.net

March 10th, 2007, 09:16 AM	#3
Daniel Epstein Trustee Join Date: Jan 2006 Location: New York, NY Posts: 1,267	I have used both methods and they both can be sound. Most gels will lose some of their color the closer and longer they are next to the light. As it ages its color correction will change so it would last longer if you put it in front of the softbox instead of the light. If you put it between the light and the softbox make sure the gel has enough space to dissipate the heat from the light or it will be damaged rather quickly. I usually use this method when I don't have a piece of gel big enough to go over the softbox. The Tota light and barndoors doesn't have very much depth so it is very difficult to put gels on it without burning them unless you can attach the gel to the inside of the softbox As for the fire hazard this depends on the quality of the softbox and proper operation of the light. Make sure you open the Tota's barn doors to full wide or you can melt them. If the metal doors melt imagine what the light can do to a gel.

March 12th, 2007, 10:05 PM	#7
Charles Hurley Regular Crew Join Date: Feb 2007 Location: Brooklyn NY Posts: 128	For Chimera softboxes they make a diffusionn that's ctb. Photoflex may have a similar product.

March 14th, 2007, 01:27 PM	#9
Ralph Keyser Major Player Join Date: Aug 2002 Location: Albuquerque, New Mexico USA Posts: 287	Just to drive home Nino's comment about light loss through CTB, remember that full CTB is nearly 2 full stops of light loss (not quite, but close enough). That means that in order to get the same level as your 500w bulb, you would need a 2000w bulb through full CTB.

March 14th, 2007, 06:12 PM	#11
Heiko Saele Major Player Join Date: Mar 2007 Location: Wurzburg, Germany Posts: 316	from the pure law of physics, the color conversion and loss of intensity through a ctb must be the same no matter at what distance you put it, I'd rather put it further away from the lamp. You'd have to use a few square inches more in the first place, but then you won't have to replace it every few hours... Outside the softbox the ctb gel should be lasting hundreds of hours (when it doesn't get hot) Oh, and maybe a 1/2 or 3/4 ctb could be enough for the color conversion you need, and they don't eat as much light.