Joseph S. Wisniewski wrote:
BDP, there's people who would like it to act like, well, anything and everything. It's cheap, and big, and that makes a great "foundation". That's why Paul has a sock for it, so you can switch it from the original 18 degree (more or less) collimation to 150 degree. It's also why he (like all soft box makers) has grids for his soft boxes and octas, so they can go from that 150 degree collimation to 40 degrees.
Chimera is so "gung ho" about that, that they sell 20, 30, 40, and 60 degree grids for their soft boxes.
But there are limits to that approach. A conventional soft box isn't that good a collimator. I've used some of mine without the front diffusion panel, and they're uneven and poorly focused. So, the only way to get narrow patterns out of them is to overdo the diffusing (those conventional 150 degree diffusers that Paul mentioned) then gird the light aggressively. That eats a ton of light. About 5 stops for a 20 degree grid over a diffuser panel. The PLM has virtually that identical pattern, it's really similar to a big box with a 20 degree grid, but 5 stops more powerful. Even close up, in a studio, that's useful. It's more power than you need to take the picture, but it helps you compose the picture. The more aggressively you modify a light, the more you need to be able to see what you've done, via modeling lights. Put a 5 stop modifier on a monolight with a 300W halogen modeling light, and you've got a whopping 10W of light to compose by.
A diffuser that doesn't scatter much light, one that just adds another 20 degrees to the 18 degree spread of a PLM, would match the 40 degree gridded box, with over 4 stops more power, and radically less cost.
Cost is a key. It's hard to appreciate how really big a PLM is. The 86 inch has about 29 ft2 of front area. My Chimera 6 foot Super Pro Plus has 27 ft2, and I think the nearly round PLM makes for more natural shadows. So, the $103 PLM can do the work of two 6 foot soft-box configurations, no grid and 20 degree grid (and that's a $1,300 configuration for the Chimera: you're talking $500 for the 6 ft box and $800 for the 6 ft 20 degree grid). The 20 degree Chimera grid weighs a ton, it strains (and warps) the box and whatever it's mounted on. The 20 degree configuration of the PLM means just taking the sock off.
I'd gladly pay $50 each for diffusers that could bump that up to matching the 40 and 60 degree Chimera grids. Heck, complete PLMs weigh less than Chimera 6 foot grids, it might be worth experimenting, spraying matte clear lacquer on a silver PLM to see if I can increase the scatter of the reflector to 40 degrees. Although I still see a lot of promise in my earlier idea about playing with diffuser material.
And an added bonus feature, PLMs focus a bit. You can't do that with a soft box. Slap on a 40 degree "silk", focus the PLM in to 6 feet, what you could do with that for product photography. It's mind boggling.
Yea, I get that, and additional modifiers, grids, etc. are fine (and welcome). My main question was about your suggestion to change the silver in the PLM itself, to make it more diffuse. I would object to that, since I value the more focused, collimated light of the bare silver PLM. Anything you want to do, or anything PCB wants to do, in terms of more add-on modifiers, I am way cool with. Just don't go making the spread on the bare silver PLM wider. That's all, and that's the only thing I didn't "get" from your earlier post.