Softbox Brands

Started Jan 21, 2011 | Discussions thread
sacentre
Senior MemberPosts: 1,158
Like?
Re: The inner diffuser (or deflector)...
In reply to Joseph S Wisniewski, Feb 18, 2011

Joseph S Wisniewski wrote:

sacentre wrote:

Joseph

Thanks for that detailed and clear explanation. Do all softboxes have two? Also, you mentioned a distance rule - a 6ft box at 6ft distance ect. Mine's a 2ft so I should use it two feet from the subject?

Thanks again

Trevor

I would like to know the answer (if there is one) to this too. I just bought an el cheapo Phottix 60 cm x 60 cm softbox kit to experiment with. The actual box is not bad, comes with an internal diffuser which attaches on 4 hooks half way down the depth (not sure what this is for. Anyone?

It's a necessary part of making the soft box perform well. Think of the soft box as a big "parabolic reflector" that collimates all the light from the flash. That means that light from the flash ends up moving pretty much forward, as a bunch of parallel rays, like a search light beam.

The front diffuser "scatters" light over a certain range of degrees, typically about 90. So, whenever that collimated light hits the front diffuser, it gets scattered over the 90 degree angle, 45 degrees up, 45 degrees down,. 45 degrees left, 45 degrees right. When you have your subject at the traditional "soft box distance", 6 feet away from a 6 foot box, 4 feet away from a 4 foot box, etc. and positioned at face height, the scatter is enough so that light from even the corners of the box gets scattered 45 degrees inward. Your subject gets the maximum light.

Now, look at where the light is in the box. About 75% of the light from the flash hits the sides of the box and gets reflected forward and collimated. Another 25% travels directly from the flash to the front opening, without ever hitting the box walls. So, that light doesn't get whacked into going forward, it's radiating outward, it's "divergent" light. At the corners, it's diverging about 45 degrees. The front diffuser can't scatter that divergent light inward enough to hit the subject, so it scatters outward and goes all over the room. It decreases the quality of the light, the central part of the "direct" light isn't divergent and makes the center of the box brighter.

The diffuser (or deflector) does two things. It reduces the amount of divergent and direct light (hence, deflector) and it provides a second "scattering", diffusing some of the divergent light into the soft box walls, so it can become collimated light.

In short, leave it in. It kills about 1/3 stop of light, but you've probably got enough power, and it makes the light you have left look better, less scatter outside the area you're aiming the box at, and more uniform (soft) light, without a harsh (specular) center.

I accept as an article of faith that you get what you pay for. It's sometimes hard to find out what that is.

Sometimes, what you pay for is the system, and the distribution and support network.

I like Chimera soft boxes. I like shooting with a grid on a softbox, it gives more control. If you get a Paul Buff soft box (love his lights), he sells just one grid, it's a 40 degree grid, I believe.

Chimera sells 5 grids, 10, 20, 30, 40, and 60 degrees. The tighter (10 or 20 degree) grids can give you soft light on a subject that just sort of "stops" off the subject, so you have total control of you subject and background lighting, independently.

As far as construction and build quality goes (as I said in my thread on umbrellas) I'm always prepared to pay more for an obvious build quality improvement over a cheaper brand but if there are any other benefits to paying a lot more, I'm not educated enough to know yet.

Shape, mostly. Number of available surfaces. And then you get into wild stuff like the Paul Buff PLM, an umbrella that mounts on the light axis using a speedring, instead of a few inches off axis, so the pattern is more precise.

It would be interesting to see lighting gear comparisons to see what if any, are the IQ benefits.

There's actually a few sites that do some of that. Rob Galbraith is one.

-- hide signature --

Rahon Klavanian 1912-2008.

Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.

Ciao! Joseph

http://www.swissarmyfork.com

Reply   Reply with quote   Complain
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow