relative efficiency of brolly vs softbox?

[Dave Pickett]

Sorry guys loads of questions at the moment, as I get to grips with my new lighting.

I am guessing that both a silver brolly and a shoot through will be more efficient than the softboxes (with an internal difusser as well as the external cover), any idea how much more efficient?

Presumably a beauty dish is more efficient still?

 

[Garry Edwards]

'Efficiency' is a pretty flawed measuring tool when comparing apples to oranges, although it is relevant when comparing apples to apples...

All things being equal (i.e. exactly the same shape at exactly the same distance) then a shoot through umbrella is the least efficient, followed by a white reflective and then a silver reflective, for obvious reasons.

Softboxes tend to have similar efficiency to a white reflective umbrella at close distances, but as the distance increases the more diffused light from a softbox spreads over a greater angle, so the efficiency decreases.

Beauty dishes are pretty much just near parabolic reflectors, so their efficiency is impressive, and doesn't diminish all that much over distance (compared to the other tools)

But none of this really matters, as long as there is enough power to start with.