Light: Does it really add up?
 

If you have, let's say, 2 fluorescent lamps of an equivalent of 250 watts each on one single fixture, is the light that they produce equal to that of a fluorescent fixture of one 500 watt lamp? I ask 'cause I've seen them being sold in both configurations. Do they have equal coverage and projection?

Well your surface area is more spread out but I think your confusing some issues here based on manufacturers misleading you. There's not a 500w fluorescent lamp in my experience although I've seen a 400w monster and it's not available in the USA. We barely have 200 watt ones like the one that I made my fluorescent softbox fixture for.

What you are seeing is that some manufacturers list the equivalent wattage as their real wattage and this is VERY misleading. It's far better to list the real wattage and then say what the "equivalent" wattage is and also list lumen output too.

So, my guess is that what you're calling a 250w bulb is really a 60watt (divide by 4) in actual wattage. A "500w" bulb really is a 125w bulb in actual wattage.

Anyway, to answer you're other question about coverage. You get more surface area with more bulbs, hence more coverage. It's just another version of a softbox which increases the surface area of a tungsten light making it soft. The more CFL bulbs you have (even without diffusion), spread out makes for even higher surface area from something that already is soft and inherently has a large surface area. Yes, fluorescent is soft because there's a larger surface area on each bulb emitting light. Put more of these together in an array and you have a larger surface area emitting light. May not even be necessary to put a silk in front of them unless you have some hot spots that need some smoothing or need to dim it a bit more.

Does that answer your question?