FORUMS: list search recent posts

Egg Crate/Diffuser question

COW Forums : Lighting Design

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Jonathan Frank
Egg Crate/Diffuser question
on Aug 5, 2012 at 6:41:19 pm

I'm going to ask a really potentially stupid question. But unfortunately I can't find any answer or illustration online.

I've used the Rifa 55 light and have just purchased one. I also purchased a 50 degree egg crate for it but have never used an egg crate before. Everything on Lowell's site says "diffuser must ALWAY be used in case of bulb explosion"

My stupid question is...does one use a diffuser with the egg crate? In putting it all together it looks like the only way to put the diffuser on would be to slip it over the egg crate. But any photo I find on the Lowell site clearly shows the grid of the egg crate visible, thus making that seem...not correct.



Return to posts index

Bill Davis
Re: Egg Crate/Diffuser question
on Aug 5, 2012 at 7:00:05 pm

Here's the deal.

If you're using standard tungsten technology, tremendous amounts of the electrical energy you feed to the lamp gets transformed into heat. Heat is very difficult to manage. So very bright very hot Lightbulbs can explode. When they do, they tend to eject hot glass fragments which can be very dangerous.

And the hotter the lamps (e.g HMIs) - the bigger the problem will be.

So the bottom line is that whenever you're using a hot, bright lightbulb - you want to have SOMETHING between the lamp and the talent to keep a failed lamps explosive hot glass discharge contained.

Pro lamps use a variety of sheilds. Some (like the venerable Lowel Totas - use metal mesh safety screens. Others use housing with a fixed glass lens (fresnels) that control the light but ALSO put a barrier between the lamp and the public.

Obviously, a lamp in a soft box is protected, since the front "diffusion" screen provides the barrier. But diffusion screens are typically removable, so if you don't use it, you've got a problem.

A fabric grid alone does NOT provide a barrier. A fabric grid is NOT a diffuser, it's a form of beam spread control. A diffuser is a reasonably solid surface designed to spread light over a larger surface. It can be plastic or fabric, but it''s NEVER something hot glass can get through.

So to sum things up. You NEVER want to use a hot light in a situation where there's nothing between the lamp itself and the talent.

If you're using a "cold light" technology like fluorescent or LED, none of this matters since explosive heat buildup pressure simply isn't an issue.

Hope that helps.

"Before speaking out ask yourself whether your words are true, whether they are respectful and whether they are needed in our civil discussions."-Justice O'Connor


Return to posts index

Jonathan Frank
Re: Egg Crate/Diffuser question
on Aug 5, 2012 at 7:04:22 pm

Not really....as it doesn't answer the question of "if you're supposed to use a diffuser AND an egg crate how the heck do you do it..." (given the poles needed to attach the light to the egg crate don't go through the diffuser...and the photos on the Lowell site don't show a diffuser over the egg crate)



Return to posts index


Rick Wise
Re: Egg Crate/Diffuser question
on Aug 5, 2012 at 7:07:21 pm

The diffuser is closest to the lamp. The egg crate goes in front. If you were to reverse the positions, the egg crate would do nothing but cut down light intensity, not channel the light. The whole purpose of the egg crate is to make the soft box a bit more directional so it doesn't spill light everywhere.

Rick Wise
Cinematographer
San Francisco Bay Area
http://www.RickWiseDP.com


Return to posts index

Jonathan Frank
Re: Egg Crate/Diffuser question
on Aug 5, 2012 at 7:13:03 pm

Thanks! (I should have said the poles barely go through the diffuser....which is why I wanted to make sure that the diffuser didn't go over the top as it seemed to fit better and be more secure that way, versus having the egg crate over the diffuser)



Return to posts index

Bob Cole
Re: Egg Crate/Diffuser question
on Aug 5, 2012 at 8:59:29 pm

[Bill Davis] "Obviously, a lamp in a soft box is protected"

Everything else in Bill's post I agree with, but I recommend covering any bare-faced bulb with a screen, even if it is in a soft box. The material in a soft box is not strong enough to contain an exploding light bulb.

Bob C


Return to posts index


Dennis Size
Re: Egg Crate/Diffuser question
on Aug 6, 2012 at 3:15:11 am

I have more than once set diffusers on fire due to the hot glass of exploding lamps penetrating right through them -- not only causing hot glass to rain down on talent but also setting fire to the diffuser. Diffusers, whether they be mylar media, silks, fotoflex or Chimera lightbanks, etc. are not safety screens.

Keep a fire extinguisher handy.

Dennis



Return to posts index

Jonathan Frank
Re: Egg Crate/Diffuser question
on Aug 6, 2012 at 3:30:21 am

y'all are inspiring confidence by the gallon (keeping fire extinguisher and plastic surgeon on speed dial!)



Return to posts index

Dennis Size
Re: Egg Crate/Diffuser question
on Aug 6, 2012 at 3:44:05 am

TELEVISION LIGHTING ..... it's not for children or the weak of heart!
It should be an Olympic Sport!



Return to posts index


Craig Seeman
Re: Egg Crate/Diffuser question
on Aug 7, 2012 at 12:26:26 pm

Manuals are very useful.
http://www.lowel.com/download/LowelRifaInstrsWeb_0510.pdf
See Attaching Soft Egg Crates

1 Unfold Egg Crate accessory. With the
diffuser already attached
, place the Soft Egg
Crate over the front of the light, inserting the
corner pins of the reflector frame into the metal
tube sockets located in the egg crate corners.

2 Secure the egg crate to the body of the
Rifa with Velcro strips located around the edge
of the reflector housing.



Return to posts index

Jonathan Frank
Re: Egg Crate/Diffuser question
on Aug 7, 2012 at 1:39:21 pm

They are! Thanks for pointing me towards it. I had scoured the Lowell site and there are no manuals or links with the eggcrate (and mine came sans manual). And this isn't the copy that came with my Rifa55...



Return to posts index

Craig Seeman
Re: Egg Crate/Diffuser question
on Aug 7, 2012 at 2:06:59 pm

It was definitely NOT easy to find on their site.
I think their site has serious usability issues.
Products should link to manuals and they don't.



Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]