PDA

View Full Version : Attaching polarizers to CFL lights



Toyon
8-Apr-2016, 07:51
I have a fairly crude light stand with two daylight balanced CFL bulbs. To cut down on reflections, I want to cross polarize. Any suggestions on how to mount 8x8 polarizing sheets below the lights so that they are not effected by heat from the lamps?

Bob Salomon
8-Apr-2016, 07:58
Polarized copy lighting a also uses a polarizer on the lens with all of the polarizes aligned with each other. One way, if you don't have holders for your lights for the filters is to mount the filters to another set of light stands places in front of your lights. If you are using a copy stand like a Kaiser or a TTI then they do make polarizing filter holders for their lamp arms.z

LabRat
8-Apr-2016, 14:56
The good news about using CFL's is that they generate much less heat than tungsten lights, so in a reflector, the gels can even be taped to the top of the reflector and hang with a little airspace at the bottom... Or a frame can be made with mattboard, plywood, etc to hold the gels... The gels can take low/medium heat, but not with hot tungsten lights, which require at least 1' of airspace between reflector & gel...

The bad news about using CFL's & crosspolarization is that the CFL's have a much lower output than tungsten and the polarizing eats light like crazy, so your exposures will be very long... And the color balance tends to get weird with these, and have a "dead" looking effect without the highlights... If you need to get rid of most all of highlights (like shooting a plastic bag full of food or stuff, or heavily textured/reflective items, good, but for general work, kinda strange looking)... And metering the shot is very difficult without shooting a lot of Polaroids (in the old days)...

I've been using CFL's for shooting macro a lot lately, and more than a foot away from the subject, the light falls off a lot, and you loose that small f-stop you started with... But excellent, cool, crisp light near the subject!!!

Steve K

AtlantaTerry
8-Apr-2016, 15:00
What about buying two inexpensive "clamp lights" from the hardware store? These come with large bowl-shaped reflectors. Screw the CFL bulbs into the socket then tape the Polarizing filters to the reflector and all is set to go.

Bob Salomon
8-Apr-2016, 15:43
The good news about using CFL's is that they generate much less heat than tungsten lights, so in a reflector, the gels can even be taped to the top of the reflector and hang with a little airspace at the bottom... Or a frame can be made with mattboard, plywood, etc to hold the gels... The gels can take low/medium heat, but not with hot tungsten lights, which require at least 1' of airspace between reflector & gel...

The bad news about using CFL's & crosspolarization is that the CFL's have a much lower output than tungsten and the polarizing eats light like crazy, so your exposures will be very long... And the color balance tends to get weird with these, and have a "dead" looking effect without the highlights... If you need to get rid of most all of highlights (like shooting a plastic bag full of food or stuff, or heavily textured/reflective items, good, but for general work, kinda strange looking)... And metering the shot is very difficult without shooting a lot of Polaroids (in the old days)...

I've been using CFL's for shooting macro a lot lately, and more than a foot away from the subject, the light falls off a lot, and you loose that small f-stop you started with... But excellent, cool, crisp light near the subject!!!

Steve K

It all depends on what LED lights you use. TV studios are lit with LED lights. So are most location news shots.

vinny
8-Apr-2016, 17:31
It all depends on what LED lights you use. TV studios are lit with LED lights. So are most location news shots.

He's using CFL's, not led's.
To the op, your gels should be fine if they touch the lamps. The clip on idea is good though.