Umbrella vs Soft Box

[gl600]

Hello,
Assuming that they are the same size, why would you buy an umbrella set up vs a soft box (and vice versa). ???
(also assuming that I do not care about the shape of the catchlight in the models eye).

 

[DScience]

soft box creates much softer light, less harsh shadows, and in essence is more 'powerful'.

 

[gl600]

but doesn't the soft light and less harsh shadows depend on the size of the light source? Why would a soft box by definition work better?
Also, how is it more powerful?

 

[Dao]

Here ...

http://www.thephotoforum.com/forum/...um-photo-gallery/187123-umbrella-softbox.html

 

[gl600]

perfect, thanks.
I should have done a search... :blushing: