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-   -   Difuser with Fluorescent tubes (https://www.dvinfo.net/forum/photon-management/114602-difuser-fluorescent-tubes.html)

Lloyd Claycomb February 11th, 2008 09:07 PM

Difuser with Fluorescent tubes
 
Are diffusers even needed when using fluorescent tubes at 6-7 feet away from the subject? Is the light pretty much diffused by the time it gets to the subject?

Paul Cascio February 12th, 2008 08:23 AM

Fluorescent lights are soft already, so you may not need any diffusion.

BTW, I'm in Clermont.

Edited for accuracy.

Marcus Marchesseault February 13th, 2008 12:45 AM

I find that some light diffusion may be necessary to completely eliminate hot spots and to prevent multiple small shadows from the separate tubes.

To directly answer Lloyd's question:

The farther a light source is from the subject the LESS diffuse it becomes. If you want soft shadows, you must have the light source be large in relation to the subject. If a light is far away, it becomes a pinpoint source so get a big fluorescent in fairly close and you get very soft shadows. If you want the really soft edges like in women's fashion photography you will need diffusers as large as your subject. The same goes with shooting cars. Cars are often shot with huge 20'x20' diffuser/reflectors to make the light sources have soft shadows and huge but dim reflections.

Try http://www.photoflex.com/ and click on "Free photo lessons" in the upper right. They have very clear explanations of the impact of "soft" light sources.

Henry Cho February 13th, 2008 04:11 AM

"diffused" is relative :). whether it's necessary or not would be an aesthetic decision on your part. putting a large silk in front of a softbox can generate beautiful, super-soft light.

Richard Andrewski February 13th, 2008 10:07 AM

Quote:

Originally Posted by Marcus Marchesseault (Post 825467)
I find that some light diffusion may be necessary to completely eliminate hot spots and to prevent multiple small shadows from the separate tubes.

To directly answer Lloyd's question:

The farther a light source is from the subject the LESS diffuse it becomes. If you want soft shadows, you must have the light source be large in relation to the subject. If a light is far away, it becomes a pinpoint source so get a big fluorescent in fairly close and you get very soft shadows. If you want the really soft edges like in women's fashion photography you will need diffusers as large as your subject. The same goes with shooting cars. Cars are often shot with huge 20'x20' diffuser/reflectors to make the light sources have soft shadows and huge but dim reflections.

Try http://www.photoflex.com/ and click on "Free photo lessons" in the upper right. They have very clear explanations of the impact of "soft" light sources.

But, when you want a smoothing effect with no cutting of light output, use the prismatic diffusion or "cracked ice" pattern styrene diffusor panels like you can get at Home Depot in the acoustic ceiling section. These are easy to cut to size and work wonders with smoothing out any tube hot spots.


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