Very basic (dumb) question about softbox

How wide-spread is the light coming out of a softbox? I got my hands on a 24x36 softbox, and the light is spread over more than 90 degrees (maybe even more) in front of the box. Is this normal? I read softbox are supposed to be very directional?

They can be made more directional via grids.

Thanks, double negative. So it is normal? What is the difference with grid only and grid+softbox then?

something id recomend doing is getting a meter and metering the light coming from the box, dont forget to meter towards the position you'l be shooting from, and hold the meter level with your eye (thats what i do anyway..)

that way by looking at the readings you'l see where the light is feathering off...

It is pretty hard to diffuse light without spreading it. The diffusion material works by sending light off in all directions, although it isn't completely scattered and the box does control that to some extent. Grids on the outside of the face of the soft box reduce the spread into a something more like a column of light.

This is quite normal and the angle of coverage will vary based on whether the front diffusion material is flush with the front of the box or if it's recessed. Generally, a softbox that accepts grids has recessed front diffusion material and a grid will give you ~40 degrees of spread, as opposed to not using a grid which can sometimes give you up to about 130 degrees coverage.

In small studios and when using controlled lighting, devices such as grids are used on softboxes, as well as using flags and gobo-like tools for further control.

This is no different from using a honeycomb grid on a strobe. A standard reflector on a strobe gives you somewhere between 50 and 80 degrees or so and grids are used to drop that down to as little as 5 degrees and as much as 40 degrees for great control and pinpoint precision, allowing you to fine tune where light goes and where it doesn't.

The light that comes from a softbox with a grid is still diffused light but with greater directionality.